TIFF vs JEPG
Mike Fox
DVDs.
I'm going to be scanning archival quality images of 35 mm slides that
in TIFF will come to 133 MB files. In JEPG, they'll be a lot less.
I'll be burning the files to a 4.7 GB DVD when I get enough to fill
one.
My question; Will I have significant quality loss to scan them as
JEPGs and burn them to a DVD as JEPGs as an archive? In dirivative
use of the images, I'd resample them to TIFFs and edit and save them
as TIFFs.
Thanks\\Mike
Rosemary
JPEG you don't get it back.
You can also back them up to a usb/firewire drive...I wouldn't save
them as JPEGs though.
R
Raphael Bustin
wrote:
First off, I assume you'd be talking about the highest-quality
ie., minimal-compression JPG settings. These will give you
file sizes about 60% smaller than the equivalent 24 bit per
pixel TIFFs.
Yes, JPG is lossy, but on a high-res scan, I defy anyone to
actually see the difference between a 24-bit TIFF and its
equivalent high-quality/low-compression JPG.
So here's what I do... I scan images as TIFFs, and when
the time comes to archive them to DVD, I keep the JPG
equivalent on my hard drive. So my DVDs have the TIF
originals, and my hard drive has equivalent JPGs. If it's
a critical application (rare) I may dig up the TIF from the
archives, but in most cases the JPG will do just fine.
rafe b
www.terrapinphoto.com
Mike Fox
loose quality, though it will be imperceptable. At 133 MB TIFFs,
this equates to 35 images to a DVD vs 60 images for JPEG. I'm going
to be scanning thousands of 35mm slides for a family history archive.
With a little luck, the DVD will last 20 years and be transcribed to
the next generation of media. It's my hope the images will travel
100s of years of progress in imaging technology as they are passed
through future generations. Skimping now makes no sense.
For now, however, 133 MB files are a bit cumbersome. I'll need to
resample them down to a usable size. Any suggestions on batch
processing bunches of images to downsize them for today's
applications?
Thanks
Mike
On Fri, 07 Apr 2006 22:05:37 -0400, Raphael Bustin <f...@bar.com>
wrote:
Raphael Bustin
>So--at highest quality JEPG, even the one and only save to DVD will
>loose quality, though it will be imperceptable. At 133 MB TIFFs,
>this equates to 35 images to a DVD vs 60 images for JPEG. I'm going
>to be scanning thousands of 35mm slides for a family history archive.
>With a little luck, the DVD will last 20 years and be transcribed to
>the next generation of media. It's my hope the images will travel
>100s of years of progress in imaging technology as they are passed
>through future generations. Skimping now makes no sense.
>
>For now, however, 133 MB files are a bit cumbersome. I'll need to
>resample them down to a usable size. Any suggestions on batch
>processing bunches of images to downsize them for today's
>applications?
Lots of programs can do that. I use a freebie called XnView.
Personally, I'd convert a file to high-quality JPG rather than
downsample it, but that's just me.
rafe b
www.terrapinphoto.com
Roger
>So--at highest quality JEPG, even the one and only save to DVD will
>loose quality, though it will be imperceptable. At 133 MB TIFFs,
>this equates to 35 images to a DVD vs 60 images for JPEG. I'm going
>to be scanning thousands of 35mm slides for a family history archive.
>With a little luck, the DVD will last 20 years and be transcribed to
Don't rely on luck. As in Vegas it only works for some.
If you are truly doing thousands you need to save high quality
duplicates and keep them in separate places.
As it stands right now, no one knows just how long optical media will
last be it CDs or DVDs that we burn.
>the next generation of media. It's my hope the images will travel
>100s of years of progress in imaging technology as they are passed
>through future generations. Skimping now makes no sense.
Data migration is usually pretty easy if the user has the capability
of reading *both* types of media which is not often the case. Or
course that is assuming there will be someone interested in doing the
migration when it needs to be done.
Another important point is continued data integrity verification. The
DVDs should be tested periodically to make sure they are not failing
and this needs to be a quality check, not just whether they can still
be read.
>
>For now, however, 133 MB files are a bit cumbersome. I'll need to
>resample them down to a usable size. Any suggestions on batch
>processing bunches of images to downsize them for today's
>applications?
Most photo apps can do that. You can set up a macro in Photoshop to
do it. Photoshop Elements and I believe Paint Shop Pro both have the
ability built in.
However you want to save the originals at the highest quality possible
now. You can always down size them, but going back up is always a
losing battle. Lost information from down sizing can not be regained.
Some important things to remember: The original film *probably will
have a longer life than the optical media if properly stored. You are
still going to have said images so how do you plan on storing them?
What do you plan on using for a catalog, or filing system? How will
you link the new digital files back to the original images. One final
caution: No matter how good your system, no matter how elaborate,
sooner or later something in it will break and most often that break
is caused by some one rather than the system.
Contrary to what some have said on here, Hard drives DO NOT MAKE a
GOOD ARCHIVAL SYSTEM!. Even in a RAID configuration they do not make
a good archival system. When it comes to data integrity failure, 95
to 99% comes from the keyboard, not from hard drive failure. So when
mirroring, or indexing the odds are when you run into a data
corruption you are going to have it mirrored and indexed. However for
that few percent it is nice to have the indexing and mirroring. If a
drive does fail and I had a 250 Gig WD fail just a few weeks ago, then
a hot swapable, indexed system is fantastic as you replace the drive
and the system will rebuild it.
For archival storage you need to go with either a high quality tape
system which needs to be refreshed on occasion and stored properly, or
optical which still has a few unknowns.
HOWEVER I hasten to add that I've only lost a few drives over the
years and as in the case with the 250, it was backed up. BTW the 250
expired just two weeks AFTER the warranty expired.
I will also add that two of the systems here have RAIDs, but they are
striped and each computer is backed up across a gigabit network.
Instead of RAID mirroring, I use drive backup.
http://www.rogerhalstead.com/scanning.htm is one place to start and a
few ideas for a project of this kind.
Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com
J. Teske
me when we are talking family history sorts of things is the
continuation of the standards for CD's or DVD's, particularly when
looking over a 100 year or so time span. I have a bunch of photos here
of grandparents and great grandparents, some of which I can date to
1895. I have them in hard copy orignal prints. Admittedly they are
faded and I have actually have been able to restore them digitally to
the point that that other than for the clothing and hair styles, could
have been taken in the last few years. Now I am making hard copies of
these and hopefully should some descendent of mine find them, they can
also preserve them in whatever medium might exist then. There are only
a few of these photos. I am now faced with the same question for
photos from my youth. I found a cache of negatives from my infancy
(during WW II) and I'm now scanning and retouching these. I am putting
them on CD-r's. Most are simply snapshots and have no reason ever to
be printed larger than snapshot size. I think what I am going to do is
have the CDr's printed up at Sam's or Costco at something like $0.13
each. I am doing the same for the hundreds of color slides I took when
my own kids were little. Color slides are passe' for family viewing
and my kids (now 40 and 39 in age) want to do scrapbooking. I'll give
them a CD-r and THEY can go to Sam's and print up a couple hundred of
these still sizable JPEGs. I am saving some really important stuff as
TIFFs.
Jon Teske W3JT (also ARRL Life member)
Roger
wrote:
It's my belief that we will need (it will be necessary) to migrate to
a new form of media for long term storage every 10 to 20 years. I
think 20 would most likely be stretching our luck well into the danger
zone.
Alan Meyer
"Mike Fox" <guyi...@yahoo.com> wrote in message
news:jcud32djpr5nm07q2...@4ax.com...
I believe that the TIFF vs JPEG issue is a red herring. I defy
you to look at an image on screen or on paper from a TIFF
vs. one from a JPEG compressed to 1/10 original size, and
tell which is which.
If you blow up the images to the point where you can see
individual pixels, you will see that some of the pixels are
different in the two images. But even then, unless you know
in advance, you won't be able to tell which was the original,
and you still won't be able to see the differences when viewed
as images instead of as individual pixels.
Furthermore, if any of your descendants view these images,
(and I hope they will - I also scan old family images for the
same reason) the tiny differences in pixel values wouldn't
mean anything to them even if they could see them. They'll
be looking at the faces, the houses, the scenes, in other words
the content.
You'll get much more mileage out of careful scanning with
good color restoration, dust removal, etc., than out of using
TIFF.
So I store my scanned family archive as JPEGs only.
The one thing that I strongly suggest that you can do for your
descendants is to write text to accompany the pictures. Write
down who the people are, what their relationships are to each
other, what they did in their lives, what they were like as people,
what those buildings and settings and scenes are in the images.
Then store those notes on the same DVDs as the images.
And don't use Microsoft Word to write the notes (or at least
don't store them as Word files). Who knows if Word will
exist 100 years from now, or if Microsoft will exist. Store them
as plain old text files that any application whatsoever can read.
Good luck.
Alan
Surfer!
<ame...@yahoo.com> writes
<snip>
>
>And don't use Microsoft Word to write the notes (or at least
>don't store them as Word files). Who knows if Word will
>exist 100 years from now, or if Microsoft will exist. Store them
>as plain old text files that any application whatsoever can read.
Who knows if 'plain old text files' or JPGs can be read in 100 years -
or if anyone will care?
--
Surfer!
Email to: ramwater at uk2 dot net
Noons
> I believe that the TIFF vs JPEG issue is a red herring. I defy
> you to look at an image on screen or on paper from a TIFF
> vs. one from a JPEG compressed to 1/10 original size, and
> tell which is which.
Now, crop the JPEG and increase its size.
What a bloody mess, eh? ;-)
What, you never cropped an image? Tsk,tsk...
> different in the two images. But even then, unless you know
> in advance, you won't be able to tell which was the original,
but I'll darn be able to tell which one is the JPEG!
> So I store my scanned family archive as JPEGs only.
Let's hope no one ever wants to see what
aunt Emilie's face really looked like in that
only group photo of her marriage. Ah yes:
you destroyed the original photo and film...
> The one thing that I strongly suggest that you can do for your
> descendants is to write text to accompany the pictures. Write
> down who the people are, what their relationships are to each
> other, what they did in their lives, what they were like as people,
> what those buildings and settings and scenes are in the images.
> Then store those notes on the same DVDs as the images.
A very good point. Duly noted.
> And don't use Microsoft Word to write the notes (or at least
> don't store them as Word files). Who knows if Word will
> exist 100 years from now, or if Microsoft will exist. Store them
> as plain old text files that any application whatsoever can read.
Another very good point.
Raphael Bustin
>but I'll darn be able to tell which one is the JPEG!
I doubt that, if it's a first-generation conversion from TIF,
and if it's high-quality (low-compression) JPG.
Obviously, JPG is inappropriate for works-in-progress.
But it can be perfectly appropriate as an archival
format, even for critical work.
The rule is: never more than one conversion to JPG.
Here's a 4000 dpi film scan snippet as JPG:
<http://www.terrapinphoto.com/jmdavis/chrome_41_jpg.jpg>
and here's the same as a TIF:
<http://www.terrapinphoto.com/jmdavis/chrome_41_tif.tif>
rafe b
www.terrapinphoto.com
Noons
Raphael Bustin wrote:
> >but I'll darn be able to tell which one is the JPEG!
> I doubt that, if it's a first-generation conversion from TIF,
> and if it's high-quality (low-compression) JPG.
At high magnification? It's very clear which ones are
JPEGs. At least the ones I take...
Note: I said "at high magnification"! That's what the
original post implied. At normal viewing in a
monitor or print, it's impossible to separate them
on first copies.
> The rule is: never more than one conversion to JPG.
I'd go along with that one. My finding as well. The
concern for me would be: IF I need to do some detail
image cropping and/or processing later on, it'll be
nearly impossible if I archived in JPEG. While with TIFF
it's all there without any loss. So I archive in compressed
TIFF. Uses more cds, but that's cheap.
For snapshot quality anything will do, 100%agreed.
> Here's a 4000 dpi film scan snippet as JPG:
sorry, without knowing how magnified the images
are it's impossible to do a comparison.
Still, the jpeg one appears to be slightly more
"muddy" in the shadows under the roof eaves.
That's consistent with what I've seen it do
in similar cases.
Don
wrote:
>I believe that the TIFF vs JPEG issue is a red herring. I defy
>you to look at an image on screen or on paper from a TIFF
>vs. one from a JPEG compressed to 1/10 original size, and
>tell which is which.
>
>If you blow up the images to the point where you can see
>individual pixels, you will see that some of the pixels are
>different in the two images. But even then, unless you know
>in advance, you won't be able to tell which was the original,
That's just patently false!
At 100% magnification (i.e. 1:1) even a JPG image at lowest
compression (i.e. highest quality) stands out like a sore thumb when
compared to the original.
If you find it hard to see simply overlay the images and flip between
them. The JPG one will have quite easily identifiable 8x8 pixel blocks
which is how JPG compression works.
>Furthermore, if any of your descendants view these images,
>(and I hope they will - I also scan old family images for the
>same reason) the tiny differences in pixel values wouldn't
>mean anything to them even if they could see them.
*Objectively* speaking that's wrong too.
JPG uses 8-bit precision simply because that's all today's monitors
can display. However, in not too distant future monitors will expand
this dynamic range and then a 16-bit (or higher) dynamic range will
become essential.
An analogy is if you view a standard TV image side by side with HDTV.
Murky shadows on a standard TV reveal tons of detail on HDTV. However,
HDTV will not reveal new detail in old (i.e. standard TV) video tapes.
What you are advising is to use standard video tapes for archiving
(without significant loss of data) and that doesn't make any sense.
>You'll get much more mileage out of careful scanning with
>good color restoration, dust removal, etc., than out of using
>TIFF.
No, you certainly will not! All that "careful scanning" and processing
will go to waste if you keep the images as JPGs in your workflow.
>So I store my scanned family archive as JPEGs only.
That's a subjective preference and everyone is, of course, entitled to
do that. But they should be aware of the conseqences. If they are,
then, more power to them! Enjoy!
However, projecting this *personal* preference and drawing false
conclusions is just factually incorrect!
By all means, archive your images as JPGs but don't mislead others
into thinking they are not losing massive amounts of data if they do
so. They may still decide to use JPGs, and that's fine too, because in
that case they made an educated choice and did not base their decision
on factually wrong (mis)information.
Don.
Alan Meyer
> >If you blow up the images to the point where you can see
> >individual pixels, you will see that some of the pixels are
> >different in the two images. But even then, unless you know
> >in advance, you won't be able to tell which was the original,
>
> That's just patently false!
>
> At 100% magnification (i.e. 1:1) even a JPG image at lowest
> compression (i.e. highest quality) stands out like a sore thumb when
> compared to the original.
I downloaded the two images that Raphael referenced in his reply
then magnified them 16 times (i.e., 4004 pixels per dimension instead
of the 1001 pixels of the original image.)
I'm not sure I can tell them apart.
Then I magnified them almost 100 times i.e., almost 10 times
as many pixels per dimension. Now, if I looked closely, I could see
that some individual pixels had different colors. But I still couldn't
see JPEG artifact squares, and still wasn't sure which image was
which without looking at the file names.
> If you find it hard to see simply overlay the images and flip between
> them. The JPG one will have quite easily identifiable 8x8 pixel blocks
> which is how JPG compression works.
Try it with the two images Raphael provided.
> JPG uses 8-bit precision simply because that's all today's monitors
> can display. However, in not too distant future monitors will expand
> this dynamic range and then a 16-bit (or higher) dynamic range will
> become essential.
Leaving aside the monitors, how much precision can the
human eye distinguish? I suspect the best eyes can only do
around 10 bits, though I'm not at all sure about that.
Furthermore, human perception is non-linear. There are some
ranges in which we are more sensitive than others. I believe
that some JPEG compression algorithms know that and take
advantage of it to produce images that are really very close to
the maximum human perception.
However I'm not an expert on this. Someone who is should post the
facts.
> That's a subjective preference and everyone is, of course, entitled to
> do that. But they should be aware of the conseqences. If they are,
> then, more power to them! Enjoy!
>
> However, projecting this *personal* preference and drawing false
> conclusions is just factually incorrect!
Your observation about personal preference is perfectly valid.
There may indeed be some people for whom the subtle
differences between TIFF and good JPEG is detectable
and objectionable.
> By all means, archive your images as JPGs but don't mislead others
> into thinking they are not losing massive amounts of data if they do
> so. They may still decide to use JPGs, and that's fine too, because in
> that case they made an educated choice and did not base their decision
> on factually wrong (mis)information.
I agree with part of that too. And I agree that people should do
their own tests and draw their own conclusions.
I'll go further and say that whether you are losing "massive"
amounts of data is also a subjective conclusion. There's no
doubt that a computer will find a signficant difference between
TIFF and good JPEG. But whether that's "massive" from a
human point of view is not obvious to me.
Finally, I want to defend my point that good scanning is more important
than saving TIFFs.
The quality of the scanner, the decisions made by the scanning
software, the adjustments for color and contrast, the cleaning of
the image and the glass plate - all have a bigger effect on final
results than TIFF vs. good JPEG.
But, as you say, people need to do their own tests to confirm
or disconfirm this for themselves.
Alan
Alan Meyer
Very interesting comparison Rafe. I could not really tell the
difference.
I've done this test with higher compression and found that
even at 10:1 compression I was not able to tell the difference
under normal, or even moderately magnified viewing conditions.
By the way, that's a fine website. I looked at about 40 of
your photos and every one of them looked excellent. You're
good at this.
Alan
Alan Meyer
good as TIFF for practical purposes, I expected that it would
ignite some controversy, but I still think that for practical
purposes, for the majority of uses and the majority of users,
it's true.
Consider how we used film before the digital era. For example:
How many of us eschewed 35mm and only used 60x60 mm (2.25
square inches) or even larger films?
I bet that the vast majority, even of serious
photographers, were using 35mm for most purposes, even
though the amount of captured detail is 1/4 of what it is
in 60mm.
How many of us used films like Panatomic-X instead of films
like Tri-X or T-MAX?
Very few people accepted the inconvenience and expense of
the slower film, even though the grain was significantly
less than for the faster films.
How many of us used fixed length lenses exclusively, even
though the sharpness was measurably better than for zoom
lenses?
Most photographers bought zooms because of the lower
price and ease of carrying a single lens instead of
multiple lenses.
Even professional photographers, depending on what branch of
photography they were in, made these compromises.
Photojournalists almost exclusively used 35mm cameras and fast
films. National Geographic, employing some of the highest paid
and best professionals in the world, primarily used 35mm slide
film.
Even portrait and commercial studio photographers generally used
60mm film for most shots. They did not generally use, and often
didn't own, 4x5 or 8x10 cameras.
Amateurs and professionals alike, both then and now, are making
very good quality images that more than meet their needs using
technologies that are not ultra-high end.
The JPEG/TIFF issue is not exactly analogous to the examples
above. The extra cost and inconvenience of TIFF is less than the
extra cost and inconvenience of large cameras and/or slow films.
But on the other hand, the quality differences between TIFF and
JPEG are far, far less (in my view) than the quality differences
between large format and 35mm film cameras, or even between high
speed and low speed films.
So all I'm saying is that we sometimes get carried away with
technical perfection and lose sight of what we're trying to do -
which is often, I would even say usually, more than achievable
with JPEG image encoding.
Alan
Roger
wrote:
>On 12 Apr 2006 20:12:04 -0700, "Noons" <wizo...@yahoo.com.au> wrote:
>
>
>>but I'll darn be able to tell which one is the JPEG!
>
>
>I doubt that, if it's a first-generation conversion from TIF,
>and if it's high-quality (low-compression) JPG.
>
>Obviously, JPG is inappropriate for works-in-progress.
>
>But it can be perfectly appropriate as an archival
>format, even for critical work.
As archival is most likely going to be called up to restore images and
we don't know to what resolution I'd not want to have to rely on first
generation jpgs. True they can be canged to TIFFs with no loss but
saving them again as jpg will again add more deteoriation.
I routinely have to restore an image or two per month back to hard
drive, but that's on a total of over 5 terabytes on-line.
>
>The rule is: never more than one conversion to JPG.
And keep the original film "just-in-case".
Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com
>
Mike Fox
have to crank a long time just to open them. I'm starting to look
into what's best for the progam.
Mike Fox
scanning for future generations and everything hinges on a future I
can't predict. How today's imaging technology will appear tomorrow is
beyond me so what someone wrote to me sometime ago seems the way to
go.
Use the best technology (resolution and color depth) you can afford
and hope that future generations transfer your work to future media
and formats.
Don
>> At 100% magnification (i.e. 1:1) even a JPG image at lowest
>> compression (i.e. highest quality) stands out like a sore thumb when
>> compared to the original.
>
>I downloaded the two images that Raphael referenced in his reply
>then magnified them 16 times (i.e., 4004 pixels per dimension instead
>of the 1001 pixels of the original image.)
>
>I'm not sure I can tell them apart.
>
>Then I magnified them almost 100 times i.e., almost 10 times
>as many pixels per dimension. Now, if I looked closely, I could see
>that some individual pixels had different colors. But I still couldn't
>see JPEG artifact squares, and still wasn't sure which image was
>which without looking at the file names.
The point is that's your personal, subjective perception. However,
objectively, there is a marked difference. Just because you yourself
can't see it or find it too minor it doesn't mean it's not there or
that it doesn't influence the workflow.
As I said last time, if you're happy with JPGs (and apparently you
are) that's great! But the problem is that's a subjective impression
which goes contrary to objective facts. But if it satisfies your
requirements, then, of course, that's all that counts.
>> JPG uses 8-bit precision simply because that's all today's monitors
>> can display. However, in not too distant future monitors will expand
>> this dynamic range and then a 16-bit (or higher) dynamic range will
>> become essential.
>
>Leaving aside the monitors, how much precision can the
>human eye distinguish? I suspect the best eyes can only do
>around 10 bits, though I'm not at all sure about that.
No, it's more like 8-bits some say as low as 6-bits. *But* (and that's
a big but!) the total dynamic range of the human eye is far larger.
What this means is that even though we only have this 6-8 bit "window"
it moves through a far greater total dynamic range our eyes can see.
For example, when going from a dark area into a bright area you're
temporarily blinded and can't see any detail. But after a while as
your eyes adjust (the 6-8 bit "window" moves to highlights) you start
seeing detail. The same goes the other way around, of course.
So even though the window itself is relatively small, it covers a
large absolute area and can move according to lighting conditions. If
you only use JPGs this total or absolute area is limited to 8 bits and
that's a massive loss of information.
>Furthermore, human perception is non-linear. There are some
>ranges in which we are more sensitive than others. I believe
>that some JPEG compression algorithms know that and take
>advantage of it to produce images that are really very close to
>the maximum human perception.
>
>However I'm not an expert on this. Someone who is should post the
>facts.
We have different sensitivity to different wavelength. In practice
this means we see green much better than red or blue. Specifically,
the perceptors in our eyes are broken down as follows: red = 30%,
green = 59%, blue = 11%. So that's the ratio used to calculate
luminance.
But that's not really the point. It's that data is being lost. First
by going from 16-bit (or 14 in case of some scanners, etc) to 8-bit.
And then if that weren't enough, reducing that further by applying JPG
compression. And that's not really suitable for archiving purposes.
Don't forget also that JPG compression level i.e. "quality" is not
standardized! Each software uses different metrics. You mentioned 10
as the maximum, well, the highest quality in Photoshop is 12. Both
numbers are totally meaningless because there is no reference.
>I agree with part of that too. And I agree that people should do
>their own tests and draw their own conclusions.
>
>I'll go further and say that whether you are losing "massive"
>amounts of data is also a subjective conclusion. There's no
>doubt that a computer will find a signficant difference between
>TIFF and good JPEG. But whether that's "massive" from a
>human point of view is not obvious to me.
It is if you look at it in context. Not only is the difference there
but once you bring in the workflow, JPG is not (objectively speaking)
suitable for archiving.
I have no problem (and indeed do it myself!) with JPGs used "for
consumption" i.e. to distribute on DVDs or upload to a web site.
The problem is editing and archiving. Just because you find it
difficult to see the differences or don't find them objectionable the
loss of data between a JPG image and the original is massive.
>Finally, I want to defend my point that good scanning is more important
>than saving TIFFs.
>
>The quality of the scanner, the decisions made by the scanning
>software, the adjustments for color and contrast, the cleaning of
>the image and the glass plate - all have a bigger effect on final
>results than TIFF vs. good JPEG.
No, as I mentioned last time that's just factually wrong. All that
work will go to waste if your workflow is based on JPGs and/or using
scanner software editing.
For example, the editing in scanning software is very limited and only
contains a small subset of necessary tools. Any editing decisions you
make there will be based on the tiny preview "keyhole" and the 8-bit
histogram. Etc. All of that will lead to (objectivelly) massive loss
of information. Even more if you do "touch ups" later.
The "proper" workflow is to scan at maximum scanner bit depth and
native resolution without using any of the scanner software editing
features (e.g. curves etc). The only exception is ICE due to the way
it's implemented (for marketing reasons :-/).
Such a scan is known as a "raw scan" and it contains everything the
particular scanner can pull out of the media. *That's* the image which
should be archived! TIFF seems the format of choice but any *lossless*
format will do as long as one does the conversions later if needed.
One then edits this image using an external editor (much better than
the cut-down versions with limited features in scanner software). The
editing should be performed at the original bit depth and resolution.
When done, one may save that image as well for the record and to be
able to go back to it without having to edit all over again.
The last step is to then convert such an image "for consumption". This
may be for printing in which case the resolution and color information
will be reduced to match the printer. Or it may be for viewing in
which case the resolution will be reduced to fit the monitor and then
saved as JPG.
The beauty of this approach is that the original is still available.
Secondly, once the monitor size or bit-depth changes (and they will!)
or a new printer is purchased or the print fades (and it will!) you go
to your original image or the saved edited image and reduce to
accommodate these new requirements.
Don.
Raphael Bustin
>
>Raphael Bustin wrote:
>> Here's a 4000 dpi film scan snippet as JPG:
>
>sorry, without knowing how magnified the images
>are it's impossible to do a comparison.
>Still, the jpeg one appears to be slightly more
>"muddy" in the shadows under the roof eaves.
>That's consistent with what I've seen it do
>in similar cases.
Mr Noons, the information is there: the film
scan is at 4000 dpi. If you know the effective
resolution of your monitor, you can calculate
the magnification. In all probabibility, your
monitor is set to around 75-100 dpi, so the
magnification is no less than 40 x.
rafe b
www.terrapinphoto.com
Raphael Bustin
wrote:
>On Wed, 12 Apr 2006 13:50:35 -0400, "Alan Meyer" <ame...@yahoo.com>
>wrote:
>
>>I believe that the TIFF vs JPEG issue is a red herring. I defy
>>you to look at an image on screen or on paper from a TIFF
>>vs. one from a JPEG compressed to 1/10 original size, and
>>tell which is which.
>>
>>If you blow up the images to the point where you can see
>>individual pixels, you will see that some of the pixels are
>>different in the two images. But even then, unless you know
>>in advance, you won't be able to tell which was the original,
>
>That's just patently false!
>
>At 100% magnification (i.e. 1:1) even a JPG image at lowest
>compression (i.e. highest quality) stands out like a sore thumb when
>compared to the original.
Sorry, that's BS. See my earlier post on this subject.
In a blind test, you could not tell them apart.
Here's a 4000 dpi film scan snippet as JPG:
<http://www.terrapinphoto.com/jmdavis/chrome_41_jpg.jpg>
and here's the same as a TIF:
<http://www.terrapinphoto.com/jmdavis/chrome_41_tif.tif>
These are each 1000 x 1000 pixel crops straight off
the scanner.
rafe b
www.terrapinphoto.com
Noons
>
> Mr Noons, the information is there: the film
> scan is at 4000 dpi.
That means nothing. I donh't know how big
or small of a crop this is. Not from the
posted urls, which simply point to an image.
Raphael Bustin
Child, right-click on the image. Your browser
tells you the size, in pixels. Or suck it into your
image editor and get the info that way.
You whined that you didn't know the magnification.
I showed you that the information was there and
that you were just playing dumb.
Now you whine that you "don't know how big
the crop is." Which is equally false, and equally
irrelevant.
The crop in question is 0.25" x 0.25" of a scan of
a slide at 4000 dpi, at the scan resolution.
Read the text on the page that those images
came from. It's all spelled out in detail.
You know how to peel back a URL, don't you,
Mr. Noons? You understand that, given this URL --
<http://www.terrapinphoto.com/jmdavis/chrome_41_jpg.jpg>
there's likely to be more of the same here?
<http://www.terrapinphoto.com/jmdavis/>
You knew that, right? Or do you enjoy showing
your ignorance at every opportunity?
But deal with the reality of what's there first.
Why does the crop size matter? Why does
the magnification matter? I've showed the
same exact image, saved as TIF and then
as JPG, and asked you to point out the
differences. You can't, so you evade.
rafe b
www.terrapinphoto.com
scan snippets page:
www.terrapinphoto.com/jmdavis
Don
wrote:
>>At 100% magnification (i.e. 1:1) even a JPG image at lowest
>>compression (i.e. highest quality) stands out like a sore thumb when
>>compared to the original.
>
>Sorry, that's BS. See my earlier post on this subject.
Or an even earlier one (as my "inconsistency alarm" went off):
--- start ---
On Fri, 27 Jan 2006 19:17:58 -0500, rafe b <rafebATspeakeasy.net>
wrote:
>Lately I have been doing more scanning
>and saving in 48-bit color though it's
>really just caving in to peer pressure.
>I still don't really see the point.
--- end ---
If you're so convinced you can't even tell JPG from TIF then scanning
at 48-bit color makes no sense at all i.e., it's inconsistent.
If someone were as convinced as you now state to be, they would scan
at 8-bit and resist the peer pressure, not succumb to it.
But, be that as it may...
>In a blind test, you could not tell them apart.
Yes, I can.
>Here's a 4000 dpi film scan snippet as JPG:
>
><http://www.terrapinphoto.com/jmdavis/chrome_41_jpg.jpg>
>
>and here's the same as a TIF:
>
><http://www.terrapinphoto.com/jmdavis/chrome_41_tif.tif>
>
>These are each 1000 x 1000 pixel crops straight off
>the scanner.
There are far too many unknowns here i.e. it appears you've done two
separate scans which, sort of, defies the whole purpose. So, before
downloading them and then digress and waste time, we need to clearly
define the testing environment.
In the current context, in order to test the JPG conversion and
minimize (eliminate) other irrelevant influences the optimal procedure
is to perform a single *raw* (!) scan using *reliable* (!) scanning
software. Why? Because, in both cases, if the scanning software itself
mutilates the image there's nothing left for JPG to mutilate.
Next, use any software of your choice to turn this *unedited* raw scan
into JPG of "highest quality". That's a flexible term since JPG
quality is not standardized, but never mind... Even with this unknown
factor i.e., one arm tied behind my back, I'm still game.
Finally, we're talking about a reasonable image (e.g. in focus, etc)
which actually contains some fine detail i.e., no underexposed black
cats in tunnels, or overexposed polar bears in snow, etc. One can
always come up with an extreme exception but I think it's quite
self-evident that's not what we're talking about here.
After that, using the *original* (unedited!) raw scan as it came off
the scanner and its JPG version, we can do a meaningful head-to-head
compare.
Don.
Raphael Bustin
wrote:
>There are far too many unknowns here i.e. it appears you've done two
>separate scans which, sort of, defies the whole purpose.
What gave you that idea, Don? You're dead wrong.
This is the same bitmap image, saved two ways.
>So, before
>downloading them and then digress and waste time, we need to clearly
>define the testing environment.
Try not wasting our time by making unfounded
assumptions about what you're looking at.
This is a scan snippet straight off the scanner. Same
scan snippet in both cases, saved two different
ways (ie., as TIF in one case and as JPG in the other.)
I said as much when I presented these images. Why are
you playing stupid? Because the results disprove your
own "expert" opinions?
rafe b
www.terrapinphoto.com
Alan Meyer
and need a good man to do scanning, Don is someone I would want
to call. I would know that the scans he did are as perfect as
one could make them.
He's clearly a knowledgeable guy and a perfectionist.
But for those of you who are just trying to scan the collection
of family snapshots, I'm not sure that this kind of perfectionism
repays the effort it costs.
Let's say you do a good job of scanning that 3-1/2x5 black and
white snapshot of your Mom in her girl scout troop. You've
scanned at a resolution that will print at 8x10 without
pixelating, and you've captured pretty much all of the detail
that was there in the print. Anybody looking at your scan will
see a very good facsimile of what was in the snapshot.
It might even look better than the snapshot. You might have
played with it a bit - increasing the contrast and sharpening it,
or you might have used your scanner software's automatic photo
retouching control to do that for you. Then you saved it,
Now what?
Do you realistically think you will ever go back to this image
and edit it? More than once? More than twice? Will it be
published some day in an art magazine? Or perhaps pored over by
historians who are looking for details of the insignia on Girl
Scount uniform buttons from the 1930's?
If you think all or any of that might happen. Don's your man.
Follow his advice. Scan at ultra high resolution. Save the raw
scanner output, or as close as you can get to it, as well as any
edited version. Use 36-48 bit image encoding and lossless
compression to save the files.
But if you think what will happen to these images is that you and
your family and your descendants may pull them out from time to
time and have a look, then isn't that all overkill?
Personally, I'll be thrilled (in advance of course, since all my
thrills will cease with my demise) if _anyone_ ever bothers to
look over the old photos I'm scanning.
What Don is recommending is absolutely right both for him and for
anyone who shares his goals of preserving the very best possible
scans. That may well include the original poster.
And as Don was the first to say, I'm right too for myself and
people sharing my goals.
If you're going to put many hours into scanning - figure out
which goals you have, and what meets your needs. Then invest the
right amount of time and megabytes to meet them.
Peace.
Alan
Raphael Bustin
wrote:
>If I ever get a job as director of the Metropolitan Museum of Art
>and need a good man to do scanning, Don is someone I would want
>to call. I would know that the scans he did are as perfect as
>one could make them.
Hahaha. Don would be too busy "disassembling" the code for
the scanner driver and complaining about the incompetent fools
that designed it.
rafe b
www.terrapinphoto.com
Bart van der Wolf
"Raphael Bustin" <f...@bar.com> wrote in message
news:aj8242dlgqmc2ll9k...@4ax.com...SNIP
> Try not wasting our time by making unfounded
> assumptions about what you're looking at.
History tells that that might be a little too much to ask for ... ;-)
Bart
Don
wrote:
>>There are far too many unknowns here i.e. it appears you've done two
>>separate scans which, sort of, defies the whole purpose.
>
>What gave you that idea, Don?
This:
--- start ---
On Fri, 14 Apr 2006 09:31:07 -0400, Raphael Bustin <f...@bar.com>
wrote:
>These are each 1000 x 1000 pixel crops straight off
>the scanner.
--- end ---
The "these" and "straight off the scanner" suggest *two scans*. One
scan saved as JPG and the other scan saved as TIFF. For the purposes
of this test, that's virtually useless because of misalignment.
>>So, before
>>downloading them and then digress and waste time, we need to clearly
>>define the testing environment.
>
>Try not wasting our time by making unfounded
>assumptions about what you're looking at.
What assumptions?
I'm asking for *clarification* exactly because I do *not* want to make
any assumptions! If you were clear, precise and methodical in your
submission (as I was in my message!) there would be no ambiguity.
I was genuinely trying to avoid exactly these pointless digressions
and waste of time - but apparently in vain... :-(
>This is a scan snippet straight off the scanner. Same
>scan snippet in both cases, saved two different
>ways (ie., as TIF in one case and as JPG in the other.)
Saved from where? From the scanner program or from an editor later?
The above again seems to suggest two scans. Has the crop been done in
scanner software or in an image editor (some versions of Photoshop
"clip" bit depth). Etc. Etc. Etc...
All those are examples of important factors with direct *consequences*
on the testing procedure which is why establishing the proper testing
environment is both essential and crucial! If you don't (or refuse to)
understand that then there's very little hope of me proving anything
to you.
>I said as much when I presented these images. Why are
>you playing stupid? Because the results disprove your
>own "expert" opinions?
Here we go... Insults...
You know very well by now that I don't respond in kind.
You will also note (or maybe not?) that I very patiently and precisely
specified the environment for an objective test. If you had any
*legitimate* objections to that you would've addressed them. You
touchy impatience seems to suggest otherwise. And your eagerness to
resort to insults confirms it.
Don.
Don
wrote:
>And as Don was the first to say, I'm right too for myself and
>people sharing my goals.
>
>If you're going to put many hours into scanning - figure out
>which goals you have, and what meets your needs. Then invest the
>right amount of time and megabytes to meet them.
That's all I'm saying!
However, the important thing (and my point) is to make those decisions
based on reliable facts. And this goes for everything, from a casual
highly compressed JPG to a meticulous drum scan, even though the
actual relevant facts in each individual case may be different.
Don.
Don
wrote:
>>If I ever get a job as director of the Metropolitan Museum of Art
>>and need a good man to do scanning, Don is someone I would want
>>to call. I would know that the scans he did are as perfect as
>>one could make them.
>
>Hahaha. Don would be too busy "disassembling" the code for
>the scanner driver and complaining about the incompetent fools
>that designed it.
So, according to you "ignorance is bliss"? In other words, Don knows
too much, and that's bad. Huh?
Since when has knowing the subject and the software comprehensively
become a "bad thing"?
That attitude may explain your other difficulties re testing.
Don.
Don
<bvd...@no.spam> wrote:
>History tells that that might be a little too much to ask for ... ;-)
Actually, it tells exactly the opposite. But you always did have
trouble with facts and reality.
History, as you again just affirmed above, also tells that you're
still pathologically obsessed with Don's messages.
Gee! My own personal stalker! I'm flattered! ;o)
And all that caused by your stewing and pining for your lovely Ed
after he was chased away by hordes of angry "VueScam" users!
Don.
Noons
> Child, right-click on the image. Your browser
> tells you the size, in pixels. Or suck it into your
> image editor and get the info that way.
That tells me the pixels of the CURRENT image,
not how much of a crop it is of whatever the original
was. It would REALLY help if you READ what I wrote
instead of jumping into stupid, childish and misplaced
paroquialism.
> You whined that you didn't know the magnification.
> I showed you that the information was there and
> that you were just playing dumb.
No, you're just demonstrating you are yet another blithering
idiot too busy with the size of his own head to even read.
Size of an image is NOT the magnification of the
image, you fool. Got it or do you need smaller words?
> The crop in question is 0.25" x 0.25" of a scan of
> a slide at 4000 dpi, at the scan resolution.
Says who? Where is the original for comparison?
What, I'm supposed to believe whatever you say
because "you posted it on the Internet"? Get lost.
> Read the text on the page that those images
> came from. It's all spelled out in detail.
No. You can shove the text where the sun
doesn't shine. And those images didn't
come from any page: you published an URL
for an IMAGE, not a PAGE. There is a difference,
although I suspect you're too much of a fool
to notice...
> You know how to peel back a URL, don't you,
> Mr. Noons? You understand that, given this URL --
>
> <http://www.terrapinphoto.com/jmdavis/chrome_41_jpg.jpg>
>
> there's likely to be more of the same here?
Yes, I do know and have known for a lot longer
than you have. However, like I said before: I couldn't
give a damn. You put the URL forward as an
example of something it isn't. It's YOUR task to
provide something that makes sense if you want to
use it in an argument. Not fishing for clicks to
your site. Got it?
> Why does the crop size matter?
Because it defines the magnification, you bumbling idiot.
> Why does the magnification matter?
Because you can't see ANY diference at low magnifications
like I said at the very start, you bumbling fool.
> I've showed the
> same exact image, saved as TIF and then
> as JPG, and asked you to point out the
> differences.
And I told you that without putting forward the exact
content of the original and the crop size and hence
the magnification, it's useless to provide such a
picture. Which part of it didn't you understand?
> You can't, so you evade.
I have proved that you're nothing but yet another
bumbling idiot peddling about for clicks to
his site and incapable of sustaining ANY argument
without resorting to childishness and utter stupidity.
I don't feel like navigatring your site for any information.
If anything, I'd be misinformed from what I've seen
here so far. If you want to enter a text discussion with
"proof", I suggest you put forward some good
argumentation instead of plugs. Otherwise you
might be shown for the fool you are.
Which basically boils down to: I don't have time
to waste with fools like you. Good bye.
Raphael Bustin
>
>I don't feel like navigatring your site for any information.
>If anything, I'd be misinformed from what I've seen
>here so far. If you want to enter a text discussion with
>"proof", I suggest you put forward some good
>argumentation instead of plugs. Otherwise you
>might be shown for the fool you are.
>
>Which basically boils down to: I don't have time
>to waste with fools like you. Good bye.
That was the longest concession of defeat I've
seen in a while, Mr. Noons.
Now, show me that a single, low-compression
conversion to JPG, from any lossless file format,
has caused a visibile loss in this image or any
other.
That was, and remains the issue, which you
have danced around for days.
rafe b
www.terrapinphoto.com
Raphael Bustin
>Raphael Bustin wrote:
>
>> Child, right-click on the image. Your browser
>> tells you the size, in pixels. Or suck it into your
>> image editor and get the info that way.
>
>
>That tells me the pixels of the CURRENT image,
>not how much of a crop it is of whatever the original
>was. It would REALLY help if you READ what I wrote
>instead of jumping into stupid, childish and misplaced
>paroquialism.
Excuse me, but what does the size of the "original"
have to do with anything? What difference does
the "magnifaction" make? These are both red
herrings.
Please explain how those other 20 million pixels
are relevant to the issue at hand (alleged JPG loss.)
Are 1 million pixels not enough for you to make
your point? How many pixels can you see, at 100%,
on your monitor at any instant?
What sort of image would you like to see as a
test case?
rafe b
www.terrapinphoto.com
Noons
> That was, and remains the issue, which you
> have danced around for days.
No, dickhead. That was NEVER the issue.
But I don't expect you to have the intelligence,
let alone the decency, of even READING
what was said.
Piss off.
Raphael Bustin
>Raphael Bustin wrote:
>
>> That was, and remains the issue, which you
>> have danced around for days.
>
>No, dickhead. That was NEVER the issue.
From your first post in this thread, Mr. Noons:
"
but I'll darn be able to tell which one is the JPEG!
"
So what **was** your point?
Or is English not your first language?
rafe b
www.terrapinphoto.com
Raphael Bustin
wrote:
>The "these" and "straight off the scanner" suggest *two scans*. One
>scan saved as JPG and the other scan saved as TIFF. For the purposes
>of this test, that's virtually useless because of misalignment.
It never happned that way, except in your imagination, Don.
>Saved from where? From the scanner program or from an editor later?
>The above again seems to suggest two scans. Has the crop been done in
>scanner software or in an image editor (some versions of Photoshop
>"clip" bit depth). Etc. Etc. Etc...
What difference would it make "where" the file was
saved from?
Your claim, and Mr. Noon's claim, is that the mere
saving into JPG causes an observable loss.
Mr. Noons, said
"but I'll darn be able to tell which one is the JPEG!"
And you said:
"At 100% magnification (i.e. 1:1) even a JPG image at
lowestcompression (i.e. highest quality) stands out like
a sore thumb whencompared to the original."
------
I said that was NOT the case for "high quality"
(eg. Photoshop "12") JPG encoding. I presented
evidence, which you and Mr. Noons are now falling
over yourselves to discredit.
I posted two versions of the same image -- the same
scan. NOT two scans. Get that through your head.
You haven't presented any evidence for your case,
because you can't. Instead, you and Mr. Noons
conjure up one irrelevant criticism after another of
my evidence and/or "methodology" as if this were
a defense of a doctoral thesis.
If you don't like my evidence, by all means please
present your own, and make sure that it's something
we can repeat using the same tools.
rafe b
www.terrapinphoto.com
Noons
>
> So what **was** your point?
Here is a clue, you stupid dickhead:
READ THE MESSAGES
> Or is English not your first language?
Don't go there, it's dangerous
ground for you...
Don
wrote:
>>The "these" and "straight off the scanner" suggest *two scans*. One
>>scan saved as JPG and the other scan saved as TIFF. For the purposes
>>of this test, that's virtually useless because of misalignment.
>
>It never happned that way, except in your imagination, Don.
I tried being civil - in spite of your outbursts - but apparently this
leads nowhere as you continue to be abusive.
And, as you very well know by now, I don't engage in such futile
exercises.
Don.
bip...@hotmail.com
> If I ever get a job as director of the Metropolitan Museum of Art
> and need a good man to do scanning, Don is someone I would want
> to call. I would know that the scans he did are as perfect as
> one could make them.
Gee I don't know, I might want someone who really did not what he was
talking about.
It is statments like this of Don's that show he knows very little
"At 100% magnification (i.e. 1:1) even a JPG image at lowest
compression (i.e. highest quality) stands out like a sore thumb when
compared to the original.
If you find it hard to see simply overlay the images and flip between
them. The JPG one will have quite easily identifiable 8x8 pixel blocks
which is how JPG compression works. "
I have done this test, unless you are saving at less the 100% quality
you can't see a difference.
Why would I want to use someone who knows so little about image file
formats?
Scott
Raphael Bustin
wrote:
>And, as you very well know by now, I don't engage in such futile
>exercises.
When you misinform, you devalue this forum and cause
knowledgeable people to depart.
When you say things like this:
"At 100% magnification (i.e. 1:1) even a JPG image at lowest
compression (i.e. highest quality) stands out like a sore thumb
when compared to the original."
without qualification, that is misinformation, plain and simple.
I've offered several counter-examples to make my point.
You've offered nothing of substance to defend yours.
rafe b
www.terrapinphoto.com
Ole-Hjalmar Kristensen
100% zoom. Just look at sharply defined diagonal lines, and it's easy
to see the JPEG compression at work. But I agree, I will not matter at
all for the content of the image.
I file everything as maximum quality JPEG.
--
C++: The power, elegance and simplicity of a hand grenade.
Raphael Bustin
<ole-hjalmar.kristensen@substitute_employer_here.com> wrote:
>If you know where to look you will definitely see JPEG artifacts at a
>100% zoom. Just look at sharply defined diagonal lines, and it's easy
>to see the JPEG compression at work. But I agree, I will not matter at
>all for the content of the image.
>I file everything as maximum quality JPEG.
Please indicate where such artifacts appear in either version
(ie., JPG or TIF) of the scan. I just don't see them.
Obviously, with severe upsampling one can induce these
effects, but they're not in the film scan, as far as I can see.
rafe b
www.terrapinphoto.com
Don
<ole-hjalmar.kristensen@substitute_employer_here.com> wrote:
>If you know where to look you will definitely see JPEG artifacts at a
>100% zoom.
Exactly.
>Just look at sharply defined diagonal lines, and it's easy
>to see the JPEG compression at work.
That's one example. Another one is areas with lots of high contrast
detail where the 8x8 pixel JPG squares are as plain as can be.
>But I agree, I will not matter at
>all for the content of the image.
>I file everything as maximum quality JPEG.
Both of those are statements of subjective opinion (i.e. a reflection
of how much one values image content). I never talk about that because
that not only depends on the context but each person has their own
individual requirements. I only talk about objective facts and, as you
yourself confirm, clearly visible JPG artifacts at 100% are a
self-evident, axiomatic fact.
Don.
Don
wrote:
>When you say things like this:
>
> "At 100% magnification (i.e. 1:1) even a JPG image at lowest
> compression (i.e. highest quality) stands out like a sore thumb
> when compared to the original."
>
>without qualification, that is misinformation, plain and simple.
No, it's a simple fact. Explained thoroughly in subsequent messages
where I tried being conciliatory by not responding to your unwarranted
abuse. Unfortunately, your reply to that calm, factual response was
more unwarranted abuse.
You were in the middle of a slug fest with our Mr. Noons so I may have
just caught some shrapnel the first time around (which is why I tried
being conciliatory and tried to calm things down) but the second batch
of abuses shows that initial outburst was not an accident.
>I've offered several counter-examples to make my point.
>You've offered nothing of substance to defend yours.
No, you did not. You offered highly processed images with no way of
confirming their veracity which all together made them meaningless in
this context.
I explicitly specified parameters required for an objective test and
you violated virtually all of them in your "examples". Climbing all
the way back to those parameters now - and risking more abuse in the
process - at this point seems like an exercise in futility.
The facts are all out there so let the reader decide for themselves. A
careful reader will arrive at meaningful conclusions, a careless
readers will spew nonsense. We've already seen examples of both.
Don.
Scott W
And you have offer exactly what in the way of samples? How hard is
this for you, show us a crop from a scan of yours that suffers visibly
from being saved as a jpeg. Just how hard is that, after all you did
say
"At 100% magnification (i.e. 1:1) even a JPG image at lowest
compression (i.e. highest quality) stands out like a sore thumb when
compared to the original."
So I did the test, here is my crop, one side was save as a jpeg the
other is the original tiff.
http://www.sewcon.com/tiff_vs_jpeg/compare.tif 2.8 MB
Note not all browsers will view a 16 bit tiff and so this might have to
be downloaded and viewed in something like Photoshop.
This is an overview of the full image
http://www.sewcon.com/tiff_vs_jpeg/overview.jpg
And for those just for grins this is the full image as a fairly highly
compressed jpeg
http://www.sewcon.com/tiff_vs_jpeg/overview.jpg 13.5 MB
Now you statement was that the jpeg would stand out like a sore thumb,
it is clear to anyone who looks at the images that this in wrong. Not
only does it not stand out like a sore thumb but I doubt there is
anyone who can tell the difference even when zooming in on the image.
Scott
rafe b
"Don" <phoney...@yahoo.com> wrote in message
news:jvhc42t6lj0bk3he9...@4ax.com...
> No, you did not. You offered highly processed images with no way of
> confirming their veracity which all together made them meaningless in
> this context.
Highly processed? Only for Noons' benefit, because
it seemed he wanted "upsampled" versions (in his words:
"Now, crop the JPEG and increase its size...")
I started with images straight off the scanner. They
can't be any more raw than that, Don.
In fact, the images I linked to weren't created for you,
they've been up on my "snippets" website for many
months, specifically as a counterexample for those
who make the same erroneous claims that you do.
Again, you've contributed nothing but words to this
thread. How about some examples to illustrate your
points? Oh, right. You can't, of course, because
your points are bogus.
rafe b
www.terrapinphoto.com
scan snippets [now includes Epson V700]
www.terrapinphoto.com/jmdavis
Scott W
> On 18 Apr 2006 14:34:56 +0200, Ole-Hjalmar Kristensen
> <ole-hjalmar.kristensen@substitute_employer_here.com> wrote:
>
> >If you know where to look you will definitely see JPEG artifacts at a
> >100% zoom.
>
> Exactly.
>
> >Just look at sharply defined diagonal lines, and it's easy
> >to see the JPEG compression at work.
>
> That's one example. Another one is areas with lots of high contrast
> detail where the 8x8 pixel JPG squares are as plain as can be.
So post a tiff of your image that has this high contrast, just how hard
is that?
Scott
rafe b
>clearly visible JPG artifacts at 100% are a
> self-evident, axiomatic fact.
In your universe, maybe. Not in mine.
rafe b
www.terrapinphoto.com
Bruce
Yes, everyone agrees that with high compression JPG artifacts can be
objectionable. But the point is that at low compression the quality can
be so good that any data loss is imperceptible even after zooming in.
Your answer when shown examples of this is to repeatedly accuse them of
lying (you question the "veracity" of the examples) and then to attack
them for taking offense to your accusations.
The fact is that if you need to save a photographic image to a limited
file size you will always get a better quality image from a JPG than a
TIF. For example, to fit 100 large images on a CD, with quality JPGs
you could use higher DPI (a very perceptible difference) than you could
with TIFs.
And Don, anyone watching sees the pattern where you provoke attacks and
then feign innocence. In this case, if you don't like the data they
show, maybe you should try and reproduce their results before publicly
announcing (on theoretical grounds) not only that they are wrong, but
that they also must be purposely lying.
Scott W
> Don,
>
> Yes, everyone agrees that with high compression JPG artifacts can be
> objectionable. But the point is that at low compression the quality can
> be so good that any data loss is imperceptible even after zooming in.
> Your answer when shown examples of this is to repeatedly accuse them of
> lying (you question the "veracity" of the examples) and then to attack
> them for taking offense to your accusations.
>
> The fact is that if you need to save a photographic image to a limited
> file size you will always get a better quality image from a JPG than a
> TIF. For example, to fit 100 large images on a CD, with quality JPGs
> you could use higher DPI (a very perceptible difference) than you could
> with TIFs.
>
> And Don, anyone watching sees the pattern where you provoke attacks and
> then feign innocence. In this case, if you don't like the data they
> show, maybe you should try and reproduce their results before publicly
> announcing (on theoretical grounds) not only that they are wrong, but
> that they also must be purposely lying.
>
photograph it can not show clear high contrast text. With 5 minutes
of work anyone can tell this is simply not true, as this image shows.
http://www.sewcon.com/tiff_vs_jpeg/text.jpg
For those who believe they see jpeg artifact here is the tiff that the
jpeg was made from.
http://www.sewcon.com/tiff_vs_jpeg/text.tif
And for those super paranoid here is the psd file, with the text layers
intact.
http://www.sewcon.com/tiff_vs_jpeg/text.psd
Now other file formats do better at this kind of image (make smaller
files) but that fact remains that there is no visible degradation from
the jpeg compression.
Scott
Raphael Bustin
wrote:
>I only talk about objective facts and, as you
>yourself confirm, clearly visible JPG artifacts at 100% are a
>self-evident, axiomatic fact.
Try this for yourself. Or don't.
1. Pick a really crisp, sharp, hi-res film scan.
Give it your very best. The more pixels, the merrier.
2. Downsample heavily, say 8x. Now you've got
an image that's razor sharp and chock-full of detail.
You'll have single-pixel transitions.
3. Now try to mess up this image using best-quality
JPG-save settings. Use Quality=Max, regardless of
how the application presents or labels it.
I can observe no JPG-related image degradation
with such settings.
Not by eye.
Not at any degree of resizing or resampling.
Not at any screen magnification.
Not with any image.
Not with any app that matters.
rafe b
www.terrapinphoto.com
Colin D
rafe b wrote:
>
> "Don" <phoney...@yahoo.com> wrote in message
<snip arguments>
OK guys, there's an easy way for Don, Noons, and others to check Rafe's
contention that there is no observable difference between a tif and a
12-level jpg.
I loaded both of Rafe's images, the tif and the jpg into Photoshop,
They are both exactly 1001 pixels square, so if scanned at 4000 ppi the
crops represent a 0.25-inch square piece of the negative or slide, and
when viewed at 100% on my monitor at 72ppi, the magnification is
4000/72, or 55x.
Then I made a duplicate image in PS of the tif file, and saved it as a
level 12 jpg, wrote it to disk and then reloaded it into PS.
OK. Results: at 400% on the screen, each pixel was visible, and at that
level there was no discernible difference among the three images side by
side, notwithstanding that Rafe's jpg was 980-odd KB and mine was
1200-odd. Maybe his was a level 10 compression. Under blind test
conditions I don't think anyone could nominate which was which.
An interesting point, though. I understood that for the best jpg
results the pixel dimensions should be divisible by 8, which 1001
certainly isn't. Since the jpg's remained at 1001 pixels, the jpg
process didn't crop the image, so maybe it ignores the extra pixel, and
just operates on the 1000 x 1000 area.
Anybody know?
Colin D.
Noons
> That's one example. Another one is areas with lots of high contrast
> detail where the 8x8 pixel JPG squares are as plain as can be.
Bingo! And why I make a point of NEVER commenting
on a "crop" of an image without having the original
ENTIRE file to compare against: it's only too easy to - intentionaly
or not - make a crop at anything other than 100% where artifacts
don't show as well or get masked by other noise effects.
With the original file that is a lot harder to do and it becomes
clear which is jpg or tiff.
> Both of those are statements of subjective opinion (i.e. a reflection
> of how much one values image content). I never talk about that because
> that not only depends on the context but each person has their own
> individual requirements. I only talk about objective facts and, as you
> yourself confirm, clearly visible JPG artifacts at 100% are a
> self-evident, axiomatic fact.
Couldn't agree more.
Scott W
> Don wrote:
>
> > That's one example. Another one is areas with lots of high contrast
> > detail where the 8x8 pixel JPG squares are as plain as can be.
>
> Bingo! And why I make a point of NEVER commenting
> on a "crop" of an image without having the original
> ENTIRE file to compare against: it's only too easy to - intentionaly
> or not - make a crop at anything other than 100% where artifacts
> don't show as well or get masked by other noise effects.
> With the original file that is a lot harder to do and it becomes
> clear which is jpg or tiff.
please if you don't like my image how about one of yours, just a small
crop will do.
In case you missed mine here it is again
I did the test, here is my crop, one side was save as a jpeg the
other is the original tiff.
http://www.sewcon.com/tiff_vs_jpeg/compare.tif 2.8 MB
Note not all browsers will view a 16 bit tiff and so this might have to
be downloaded and viewed in something like Photoshop.
This is an overview of the full image
http://www.sewcon.com/tiff_vs_jpeg/overview.jpg
And for those just for grins this is the full image as a fairly highly
compressed jpeg
http://www.sewcon.com/tiff_vs_jpeg/overview.jpg 13.5 MB
Scott
rafe b
"Noons" <wizo...@yahoo.com.au> wrote in message
news:1145546164.4...@v46g2000cwv.googlegroups.com...
> Bingo! And why I make a point of NEVER commenting
> on a "crop" of an image without having the original
> ENTIRE file to compare against: it's only too easy to - intentionaly
> or not - make a crop at anything other than 100% where artifacts
> don't show as well or get masked by other noise effects.
> With the original file that is a lot harder to do and it becomes
> clear which is jpg or tiff.
You sure were commenting on crops on 4/12/06.
Here are your exact words:
"Now, crop the JPEG and increase its size.
What a bloody mess, eh? ;-)
What, you never cropped an image? Tsk,tsk..."
So stop whining already. The burden is on YOU to
show us even ONE example of high-quality JPG
visibly degrading an image. Preferably from some
application I've heard of.
Any image, any size, by whatever means. Just do it.
Until then, you're just blowing smoke.
rafe b
www.terrapinphoto.com
Don
wrote:
>Yes, everyone agrees that with high compression JPG artifacts can be
>objectionable. But the point is that at low compression the quality can
>be so good that any data loss is imperceptible even after zooming in.
That was never the subject, Bruce. It's an unrelated tangent. Please
read the messages.
To avoid digression I won't comment on the content. On a procedural
point, "objectionable" is a subjective term. I never question
subjective statements. All I talk about in these cases are facts.
That's how these things spiral out of control. People *assume* and
attribute things that have never been stated! Others then parachute
and pick up on this (without bothering to check the thread or the
facts) and pretty soon we have a self-generated feedback loop making
ever more baseless and outrages assumptions, etc.
>Your answer when shown examples of this is to repeatedly accuse them of
>lying (you question the "veracity" of the examples) and then to attack
>them for taking offense to your accusations.
Again, that's a misinterpretation of the facts. The parameters for an
*objective* test have been clearly stated. When the provided examples
violate virtually all of them then they are clearly unsuitable.
Instead of jumping the gun and posting such unsuitable examples an
objective reaction (the proper procedure) is to calmly challenge the
parameters first (with facts!) so as to establish the common baseline,
etc. Instead, all we've seen is a rush to abuse and name calling!
As to veracity, you bet the images need to be thoroughly vetted!
That's the cornerstone of objective scientific examination i.e.
establish an objective testing environment!
But if people respond to calm, factual messages with abuse and then
continue to hurl abuse even after one explicitly refuses to respond in
kind, it's quite clear they have already made up their minds and
nothing will convince them otherwise. They are just spoiling for a
fight and that has nothing to do with objective scientific discovery.
Which is why this thread has now deteriorated into a hopeless exercise
in futility and why I only make procedural comments.
>The fact is that if you need to save a photographic image to a limited
>file size you will always get a better quality image from a JPG than a
>TIF. For example, to fit 100 large images on a CD, with quality JPGs
>you could use higher DPI (a very perceptible difference) than you could
>with TIFs.
Again, that has nothing to do with the subject matter. Please read the
thread from the beginning.
>And Don, anyone watching sees the pattern where you provoke attacks and
>then feign innocence.
You got that totally wrong, Bruce, I'm afraid. They work themselves
into a frenzy all on their own! :-(
Please provide quotes *in context* to support this assertion! Again,
the key phrase is *in context*! And be specific and precise!
The mere fact that I never respond to abuse speaks volumes. The
problem is they immediately enter into a self-perpetuating feedback
loop drawing on each other's misinterpretations and unrelated
tangents, instead of actually reading the messages.
Once that starts all further discussion becomes impossible and
pointless.
>In this case, if you don't like the data they
>show, maybe you should try and reproduce their results before publicly
>announcing (on theoretical grounds)
And there's the rub! Are you questioning the theory behind the facts?
Of course, not. You're glossing over it even though it's the *key* and
the only thing that's important here! What you are doing (in the
following paragraph) is attributing emotional "conclusions" and
"statements" to me I have *never* stated and which have nothing to do
with the subject matter.
That's why it's essential to *read*, not "read into"!
And then someone parachutes into the discussion (without bothering to
read it in full) and takes this wrong "conclusion" and "expands" on
it, moving ever further from the subject matter and getting ever more
excited in the process (the notorious feedback loop) with
unsubstantiated accusations flying and abuse growing by the minute.
At this point there are basically two courses of action. Try to calm
them down (virtually never worked so far) and draw them back to the
subject matter or, let the facts (the record) stand and speak for
itself thereby avoiding further futile digressions.
> not only that they are wrong, but
>that they also must be purposely lying.
And that's a prime example of what I'm talking about.
Please provide a *single* quote *in context* where I have accused
anyone of lying. Be precise and specific.
Don.
rafe b
<the usual bs>
You can pile it on but you're getting nowhere.
Your credibility is nil.
Show us an example where an image file has
been visibly degraded by a save to JPG while
using "high-quality" JPG-save settings.
rafe b
www.terrapinphoto.com
Scott W
> On Wed, 19 Apr 2006 12:01:13 -0400, Bruce <XXb...@XvirginiaX.Xedu>
> wrote:
>
> >Yes, everyone agrees that with high compression JPG artifacts can be
> >objectionable. But the point is that at low compression the quality can
> >be so good that any data loss is imperceptible even after zooming in.
>
> That was never the subject, Bruce. It's an unrelated tangent. Please
> read the messages.
>
> To avoid digression I won't comment on the content. On a procedural
> point, "objectionable" is a subjective term. I never question
> subjective statements. All I talk about in these cases are facts.
Well Don you did say
"At 100% magnification (i.e. 1:1) even a JPG image at lowest
compression (i.e. highest quality) stands out like a sore thumb when
compared to the original. "
And there have been counter examples posted, and yet you seem unable to
post an exmple that shows the jpeg standing out like a sore thumb.
Why is it that you can't post this image that will stick out as a sore
thumb when saved as a jpeg?
If you don't have a place to post the tiff file just email it to me and
I will be happy to put it up, send it to bip...@hotmail.com
I believe the truth is you made a statment that was way off base and
just plain wrong.
If a jpeg is really as bad as you say you should be able to pick a crop
from just about any of your scans as a test case.
Scott
rafe b
> The mere fact that I never respond to abuse speaks volumes.
No, Don, you speak volumes on general principle.
You "only respond to procedural matters" because
you lost this debate, days ago, but haven't the sense
or grace to admit it.
rafe b
www.terrapinphoto.com
Noons
> Well I did give you the entire file to compare too in my sample. But
> please if you don't like my image how about one of yours, just a small
> crop will do.
>
> In case you missed mine here it is again
Sorry, will be away for a few days. Will look into this when
I come back. Thanks for providing the full file to have a look at.
Scott W
> Sorry, will be away for a few days. Will look into this when
> I come back. Thanks for providing the full file to have a look at.
More to the point, when you have time post an image of yours that you
believe would look worse as a jpeg. Untill you do this thowing rocks at
other's examples is rather silly.
Scott
Noons
> You sure were commenting on crops on 4/12/06.
> Here are your exact words:
Which once again, you have shown to be unable to
understand and therefore have distorted their meaning.
> So stop whining already.
The only one still whining is you, moron.
> The burden is on YOU to
> show us even ONE example of high-quality JPG
> visibly degrading an image.
There is no burden whatsoever on me from you:
I already explained to you that whatever you say
on this subject is irrelevant. Now, get lost.
I'm to busy to waste time on the likes of trolls like you.
Noons
>
> More to the point, when you have time post an image of yours that you
> believe would look worse as a jpeg.
I have in the past. Will put them up again soon.
> Untill you do this thowing rocks at
> other's examples is rather silly.
Sorry, the ones from rafe were not examples: they were totally out
of context. I did not throw rocks at yours for the simple reason that
I did not see them. Or are you and rafe one and the same? If so,
I seriously advise you to stop using various aliases: one is
enough.
Scott W
> be downloaded and viewed in something like Photoshop.
> This is an overview of the full image
> http://www.sewcon.com/tiff_vs_jpeg/overview.jpg
> And for those just for grins this is the full image as a fairly highly
> compressed jpeg
> http://www.sewcon.com/tiff_vs_jpeg/overview.jpg 13.5 MB
>
http://www.sewcon.com/tiff_vs_jpeg/fullimage_high_compress.jpg 13.5 MB
I also went ahead and put the full image up as a high quality jpeg
http://www.sewcon.com/tiff_vs_jpeg/fullimage.jpg 30 MB.
The full tiff image is over 220 MB so I won't be putting that up.
Scott
Scott W
Gee Noons, if you have a sample that prove us wrong how hard would it
be to post it?
You feel there is no burden on you? well that is true to an extent but
your failing to post any kind of image to back your claims does make
you look like the kind of person who likes to make bold statments,
wrong but bold, and will not back down from them no matter how silly
they end up being.
Scott
Scott W
So why keep telling us what is wrong with Rafe's and just post your
own?
Is it really that hard?
FWIW I think rafe's examples shows very well that you havn't got a clue
about what you talking about.
Scott
Raphael Bustin
>Sorry, the ones from rafe were not examples: they were totally out
>of context. I did not throw rocks at yours for the simple reason that
>I did not see them. Or are you and rafe one and the same? If so,
>I seriously advise you to stop using various aliases: one is
>enough.
You can't imagine that two different people, six
thousand miles apart, could *independently* call
you on your mis-statements and subsequent evasion?
You and Don have both made outrageous claims
and failed to back them up with a *single example.*
Scott and I have provided, collectively, at least
a half dozen. You and Don have been asked
numerous times to provide examples. But all
you do is dis' ours.
Called on your ignorance, you whine, obfuscate,
and smear. What a guy.
rafe b
www.terrapinphoto.com
Bruce
Deny your aggressiveness all you want. Here you are accusing me of not
having read the thread, which is an unfounded insult.
Don wrote:
> On Wed, 19 Apr 2006 12:01:13 -0400, Bruce <XXb...@XvirginiaX.Xedu>
> wrote:
>
>> Yes, everyone agrees that with high compression JPG artifacts can be
>> objectionable. But the point is that at low compression the quality can
>> be so good that any data loss is imperceptible even after zooming in.
>
> That was never the subject, Bruce. It's an unrelated tangent. Please
> read the messages.
Here is a statement about tiff vs jepg (which is the subject line of the
thread):
> If you blow up the images to the point where you can see
>>individual pixels, you will see that some of the pixels are
>>different in the two images. But even then, unless you know
>>in advance, you won't be able to tell which was the original,
And here is a direct quote from you attacking it:
> That's just patently false!
>
> At 100% magnification (i.e. 1:1) even a JPG image at lowest
> compression (i.e. highest quality) stands out like a sore thumb when
> compared to the original.
Numerous people have posted examples to show that this is not
necessarily the case for high quality jepgs. Your response has been to
question the "veracity" of their examples.
Well my own experience is that you are wrong. If you are interested is
"truth" and "facts" post examples to educate us and show us conditions
where a single high quality jepg compression does cause visible image
degradation.
My understanding is that the jepg standard uses several separate
compression schemes most of which are disabled at the higher quality
settings, but each software package implements the details differently,
hence the need for actual testing.
Raphael Bustin
>If I may digress for a moment: how did you make this scan (what scanner [looks
>like a KM Scan Elite] and what photographic material were used)? Did you edit
>the scans in any way?
>It looks extremely noise-free, whereas all my scans suffer from heavy 'color
>noise'. I use the KM Scan Elite 5400 old model, and color negatives only of
>different brands.
The problem isn't with your scanner.
Color negatives will always show more noise than
positives when scanned, because negatives have
a much smaller density range and therefore need
more tonal expansion (decompression.)
AFAIK, most of Scott's images come from digital
capture. Scott's a wizard at stitching these to form
large, seamless composites. That's why his images
are so clean.
rafe b
www.terrapinphoto.com
Scott W
clean. I figured these would be good test images since they have much
less noise and far more detail then any scan of 35mm film that I have
ever seen. With a very clean image it will be easier to see how much
is loss saving it as a jpeg. Noons would have us believe that you can't
zoom in on a jpeg and see the same level of detail that you can in a
tiff, clearly he totally wrong.
FWIW when I scan my work flow is to scan directly into Photoshop,
adjust and then save as a HQ jpeg. I did a bunch of testing and found
no real advantage of saving as tiffs.
When I stitch I will often stitch into a psd file, more for the layers
then anything else.
For my test image I stitched directly into a 16 bit / color tiff,
something that I can do but rarely do.
Scott
Don
<Col...@killspam.127.0.0.1> wrote:
>I loaded both of Rafe's images, the tif and the jpg into Photoshop,
>They are both exactly 1001 pixels square, so if scanned at 4000 ppi the
>crops represent a 0.25-inch square piece of the negative or slide, and
>when viewed at 100% on my monitor at 72ppi, the magnification is
>4000/72, or 55x.
Without getting into details, for an objective test you have to scan
raw, in other words disable everything. One common trap often missed
is interpolation. There are many such pitfalls which is why testing
parameters are so crucial. This goes for any objective test.
>Then I made a duplicate image in PS of the tif file, and saved it as a
>level 12 jpg, wrote it to disk and then reloaded it into PS.
>
>OK. Results: at 400% on the screen, each pixel was visible, and at that
>level there was no discernible difference among the three images side by
>side
There are many reasons why that's not a good procedure (the same goes
for layers) but I won't get into any of that now. Instead of side by
side, open both images independently. Next, click on the magnifier and
set the checkmark "Resize windows to fit". Finally, double-click the
magnifier for each to blow up to 100% and - if the images are larger
than the screen - this will also automatically align and overlay them.
NOTE: Photoshop (at least my version) may be cranky when lining up
images using the above process. This alignment will *only* work if you
haven't changed image size after you opened them! There's a workaround
but the easiest thing is to just do exactly as I explained above.
After that use Control/Tab to flip between the two images. If you
scroll them both by the same amount (scroll, Control/Tab, scroll),
they will remain aligned. Look for "lines" i.e. sudden and distinct
borders between neighboring areas. That's the JPG 8x8 square.
Too much magnification may be as bad as too little. I find that (for
all purposes actually!) ~300 magnification seems to work the best.
>Under blind test
>conditions I don't think anyone could nominate which was which.
As I also mentioned even if everything was done properly up to this
point a lot depends on image content. If you're looking at "black cats
in tunnels" or "polar bears in snow" you won't see much.
But even if you're looking at an image segment where JPG artifacts are
most pronounced it's still a subjective call unless you know what to
look for. But to a trained eye JPG stands out like a sore thumb.
>An interesting point, though. I understood that for the best jpg
>results the pixel dimensions should be divisible by 8, which 1001
>certainly isn't. Since the jpg's remained at 1001 pixels, the jpg
>process didn't crop the image, so maybe it ignores the extra pixel, and
>just operates on the 1000 x 1000 area.
>
>Anybody know?
That's not quite correct. JPG itself works by dividing the image into
8x8 squares and compressing them individually. That's why the border
between two neighboring squares is visible. In general, the algorithm
only takes into account pixels within that 8x8 square. The square next
to it is "on its own" which is why there is a border. If the image is
not divisible by 8 there are a number of strategies to compensate for
the missing pixels but that should not affect the rest of the image.
Don.
Don
>> That's one example. Another one is areas with lots of high contrast
>> detail where the 8x8 pixel JPG squares are as plain as can be.
>
>Bingo! And why I make a point of NEVER commenting
>on a "crop" of an image without having the original
>ENTIRE file to compare against: it's only too easy to - intentionaly
>or not - make a crop at anything other than 100% where artifacts
>don't show as well or get masked by other noise effects.
>With the original file that is a lot harder to do and it becomes
>clear which is jpg or tiff.
Exactly! Which is why establishing unbiased testing environment is
crucial if the test results are to have any meaning. And also the
first step in any objective methodology.
Our worthy interlocutors, however, are too busy hurling insults to
even notice that, let alone even make an attempt at a level playing
field. With such entrenched feelings trying to reason with them, at
this point, is futile.
>> Both of those are statements of subjective opinion (i.e. a reflection
>> of how much one values image content). I never talk about that because
>> that not only depends on the context but each person has their own
>> individual requirements. I only talk about objective facts and, as you
>> yourself confirm, clearly visible JPG artifacts at 100% are a
>> self-evident, axiomatic fact.
>
>Couldn't agree more.
Unfortunately, others have made up their minds long time ago (from the
start) and are now just spoiling for a fight. My refusal to enter into
pointless name calling and abuse just seems to make them angrier.
I do bend over backwards in order to be as objective and as fair as
can be. But that should not be confused with bending in the other
direction, as some here would have me do! ;o) No chance of that, I'm
afraid.
Don.
Scott W
Don, you are so full or crap it is amazing, where is you image?
Just how hard is this for you?
You don't have a clue what you are talking about, if you did you could
post an image in 5 minutes.
After all if the jpeg will stand out like a sore thumb as you have said
it will then just about any crop from any of your scans should show
this.
Just post a 500 x 500 crop of a tiff, not hard is it?
If you don't have a place to post it no problem just email it to me and
I will post it
bip...@hotmail.com.
Untill you can post an image that shows the jpeg sticking out like a
sore thumb none of your words mean a thing.
Others have posted image that show you are full of it and you attack
how the images were taken, so post your own.
Scott
Don
wrote:
>Here you are accusing me of not
>having read the thread, which is an unfounded insult.
No, an objective fact without even a hint of a personal attack, as
will be shown in the following paragraph.
>>> Yes, everyone agrees that with high compression JPG artifacts can be
>>> objectionable. But the point is that at low compression the quality can
>>> be so good that any data loss is imperceptible even after zooming in.
>>
>> That was never the subject, Bruce. It's an unrelated tangent. Please
>> read the messages.
>
>Here is a statement about tiff vs jepg (which is the subject line of the
>thread):
>
>> If you blow up the images to the point where you can see
>>>individual pixels, you will see that some of the pixels are
>>>different in the two images. But even then, unless you know
>>>in advance, you won't be able to tell which was the original,
>
>And here is a direct quote from you attacking it:
>
>> That's just patently false!
>>
>> At 100% magnification (i.e. 1:1) even a JPG image at lowest
>> compression (i.e. highest quality) stands out like a sore thumb when
>> compared to the original.
Now then, what does that *objective* statement of fact have to do with
your *subjective* feelings above (on top) about individual estimation
of JPG artifacts ("objectionable", "good", etc)?
I've started out (and repeated it often enough, last time in my reply
to you!) by stating that *subjective* feelings (what is good, what is
objectionable) is *not* the subject and, indeed, said words to the
effect "to each his own" which Alan acknowledged (!) but many others
seem to miss as they trip over themselves to hurl insults and abuse.
So, talking about *subjective* perception i.e. how much is "too much"
or what "looks good" is *not* the subject! Which is why I (calmly and
*politely*!) merely suggested reading the thread again. No insults!
>Numerous people have posted examples to show that this is not
>necessarily the case for high quality jepgs. Your response has been to
>question the "veracity" of their examples.
No, again that's just factually incorrect. For starters, there's
nothing there to even test the veracity of!!
You're parachuting into the middle of the thread and misreading a
single word, drawing totally unsubstatiated conclusions from that and
thereby missing the context completely. Which, again, is why I (calmly
and politely!) suggested reading the whole thread again and taking the
full context into account.
From that, in a nutshell, my response was: "First we have to establish
an objective testing environment" and then proceeded to outline some
parameters to cover the basics. Veracity of data (from *both* ends!)
is an *essential* part of objective testing! As is something called
"can't be falsified"!
STOP! Don't jump to wrong conclusions now as you have re veracity!
Please read up about this, first! This "can't be falsified" is *not*
an accusation but a most fundamental aspect of objective testing. It
protects *both* sides from *inadvertent* errors and assumptions. (In
science, one way to verify a theory is by proving it can't be
falsified.)
Anyway, the response to my trying to define an objective testing
environment was insults and abuse (repeat: which I did *not*
return!!!) and posting of so-called "examples" which violate virtually
all conditions for an objective test showing they either did not read
or did not understand the thread.
To preempt your reply, that's not an insult but a fact! If they read
or understood the thread they wouldn't have posted useless "examples".
>Well my own experience is that you are wrong. If you are interested is
>"truth" and "facts" post examples to educate us and show us conditions
>where a single high quality jepg compression does cause visible image
>degradation.
As I already indicated, at this point, that's a total waste of time
for a number of reasons e.g.:
- If people start the discussion by hurling insults (without reading)
what hope is there they will now all of sudden become reasonable?
- If people can't even grasp the most elementary parameters for an
objective test (e.g. rush with unsuitable "examples" violating and
ignoring explicit instructions) what hope is there they will all of a
sudden become thorough and reliable?
Especially in their current overagitated state?
And, no, that's not an insult, but a fact. How else do you explain
that after I went through all the trouble of outlining the basic
parameters the response was to totally ignore them (not even challenge
them!) but just go ahead and post totally unsuitable "examples"
violating all of the most elementary principles of objective testing?
So, the only prudent course of action at this point is to ignore the
insults and abuse (so as not to perpetuate a useless thread) and focus
on the facts which is I have been doing and what I'm doing here. I've
given enough information for anyone who wants to perform the tests
themselves and will be happy to provide more. Therefore, a careful
reader can take it from there.
>My understanding is that the jepg standard uses several separate
>compression schemes most of which are disabled at the higher quality
>settings, but each software package implements the details differently,
>hence the need for actual testing.
Without getting into details there are two key aspects: one, the
original JPG specs are very "flexible" (no set quality scale) and two,
there are no provisions for lossless compression. That's all we *need*
to know in the current context. Knowing how JPG works (e.g. the 8x8
pixel squares) is helpful, but not really essential.
Don.
Raphael Bustin
Don, you're such an shameless, clueless gasbag.
Instead of tiliting at strawmen or opining aimlessly
about science and methodology, please just show us
***one example*** to prove whatever point you're
making about JPG.
Your words have lost all credibility.
rafe b
www.terrapinphoto.com
Scott W
> So, the only prudent course of action at this point is to ignore the
> insults and abuse (so as not to perpetuate a useless thread) and focus
> on the facts which is I have been doing and what I'm doing here. I've
> given enough information for anyone who wants to perform the tests
> themselves and will be happy to provide more. Therefore, a careful
> reader can take it from there.
Come on Don, you said the jpeg would "stick out like a sore thumb".
When shown examples showing that you can't tell the difference you
have said they were not valid.
Why can't you post one example?
Scott
Alan Meyer
news:uJKdnfHCnLcuoaDZ...@comcast.com...
> ...
> I believe that the TIFF vs JPEG issue is a red herring. I defy
> you to look at an image on screen or on paper from a TIFF
> vs. one from a JPEG compressed to 1/10 original size, and
> tell which is which.
>
> If you blow up the images to the point where you can see
> individual pixels, you will see that some of the pixels are
> different in the two images. But even then, unless you know
> in advance, you won't be able to tell which was the original,
> as images instead of as individual pixels.
...
After all the controversy I went back and looked at the images
I've been making and saving - both from my scanner and from
my digital camera. What follows are my __subjective__
impressions. I'm not claiming that everyone else will perceive
things the way I do, but I bet a lot of people will see the same
things.
My normal technique is to save using JPEG at compression
levels of between 10:1 and 20:1. I arrived at those numbers by
trying numerous different compression levels from 3:1 up to
100:1, on a number of different images from high detail to low
detail subjects, and comparing the images. The actual
compression I use depends on settings in my scanner, my
camera, or in the GIMP, which produce results that I liked.
The output of these settings is typically between 10 and 20
to 1, depending on the detail found in the image.
Going back after all of the discussion, I wanted to see if in fact
there were artifacts that I had missed. Here's what I found:
If I magnified my images 4 times, (double each dimension), I
could often see JPEG digital artifacts - i.e., compression squares.
Pixelation of diagonal lines also became visible, but that's a
digital artifact, not a specifically JPEG artifact. Other JPEG
artifacts, such as the clumping of colors in expanses of small
color change areas such as the sky, were sometimes visible
but usually not.
Then I reduced the images back to original size, keeping my
eyes focussed on the JPEG square borders. To __my eye__,
the JPEG artifacts disappeared. Back at 1:1 resolution, try as
I might, I could not see the squares.
It has been asked, "Don't you ever crop?" The answer is, yes,
I do. But if I need to crop and blow up an image, I do that by
scanning at a higher resolution, not be reducing JPEG
compression. As someone said earlier (Scott perhaps?) for
any given number of bytes, we'll always get a better image out
of JPEG than TIFF. If I need to blow up a small part of an
image, I can always get better results by scanning to more
pixels, then compressing with JPEG, than by scanning with
fewer pixels and saving in lossless compression. The
non-compression related artifacts such as diagonal line
pixelation will always look better in the higher resolution scan.
So, I will go even further than some of the JPEG defenders have
gone in this thread and say that some of us don't even require
the highest quality JPEGs. For some of us (I suspect for many
of us) something less than that will work just as well.
Finally, I will reiterate that my practices aren't right for every
viewer or every application. Some people want and/or need
higher quality images and don't care about the extra storage.
Many people scan at higher resolutions than I do, and save
images with less or no lossy compression.
However, I bet that at least some of the people that insist on
these high quality images are kidding themselves.
This whole debate reminds me of a time almost 40 years ago
when I was working as photographer for my college newspaper.
I was using a Yashica rangefinder 35 mm camera that I had
bought for a few bucks in a pawn shop. It was all I could afford.
Another fellow, from a wealthier family I guess, had a Leica.
I acknowledged that his Leica would take sharper images than
my Yashica, but said that for many subjects and shooting
conditions it would be very hard to tell the images apart. He
became very indignant and challenged me to a test. He pointed
his camera at something and said let's both shoot this image.
I said, "There's not enough light, we'll be shooting at 1/15
second shutter speed and get blur from not holding the
cameras steady."
He replied, "I can hold the camera steady at 1/15 second!"
(Anyone who has studied photography knows that is false.)
It's easy to get wrapped around the axle on a few aspects
of image quality and lose sight of the big picture of what
you're really trying to do.
Alan
Raphael Bustin
wrote:
>After all the controversy I went back and looked at the images
>I've been making and saving - both from my scanner and from
>my digital camera. What follows are my __subjective__
>impressions. I'm not claiming that everyone else will perceive
>things the way I do, but I bet a lot of people will see the same
>things.
>
>My normal technique is to save using JPEG at compression
>levels of between 10:1 and 20:1. I arrived at those numbers by
>trying numerous different compression levels from 3:1 up to
>100:1, on a number of different images from high detail to low
>detail subjects, and comparing the images. The actual
>compression I use depends on settings in my scanner, my
>camera, or in the GIMP, which produce results that I liked.
>The output of these settings is typically between 10 and 20
>to 1, depending on the detail found in the image.
Compression ratios of 10:1 and 20:1 are not characteristic
of best-quality JPG.
What Scott and I are talking about is what Photoshop used
to call "Quality 10" and what it now calls "Quality 12".
XnView calls it a 10 also.
At these settings, JPG files are typically about 0.4x the
size of the corresponding 24-bit TIF.
At 10:1 or 20:1 compression, artifacts will be apparent.
rafe b
www.terrapinphoto.com
Don
wrote:
>After all the controversy I went back and looked at the images
>I've been making and saving - both from my scanner and from
>my digital camera. What follows are my __subjective__
>impressions. I'm not claiming that everyone else will perceive
>things the way I do, but I bet a lot of people will see the same
>things.
Only the ones that keep an open mind!
>If I magnified my images 4 times, (double each dimension), I
>could often see JPEG digital artifacts - i.e., compression squares.
Using higher compression rates (i.e. lower quality setting) will of
course accentuate the artifacts.
Actually, I usually suggest that as a good way to train one's eye to
spot them. In other words, do a series of JPGs with different
compression settings and then cycle through *overlayed* (!) images.
Going from lowest quality to the original TIF will then identify
problem areas. Once you know what the artifacts look like, it will be
easier to spot them elsewhere without going through this process.
>So, I will go even further than some of the JPEG defenders have
>gone in this thread and say that some of us don't even require
>the highest quality JPEGs. For some of us (I suspect for many
>of us) something less than that will work just as well.
Absolutely! Like I said, I myself use JPGs (and not even top quality!)
when exchanging snapshots with friends, for example.
>However, I bet that at least some of the people that insist on
>these high quality images are kidding themselves.
No, that's wrong as I explain earlier. You're making assumptions about
how they use the images and their intentions.
What you see now is not the only consideration. For example, when
monitor size or bit-depth change (and they will!) or you get a new
printer or the print fades (and it will!) your archived JPGs will not
use all of the capabilities of these new devices.
In other words, if you archive your images as JPGs they will look
murky on an HDTV. Those who archived at full resolution and bit depth
will be able to use (i.e. see) the full dynamic range of an HDTV.
Therefore, the only way to preserve all information is to archive at
native resolution and bit depth.
Now, if they don't care and consider murky 8-bit JPGs on HDTV "just
fine" then, of course, there's nothing wrong with that.
But what is wrong is to use that subjective preference and project it
by claiming that others archiving at full resolution and bit-depth are
kidding themselves. They are not because they are saving real data.
>It's easy to get wrapped around the axle on a few aspects
>of image quality and lose sight of the big picture of what
>you're really trying to do.
Or, as I like to say, context. That's why I step back every now and
then and ask myself if I'm going too far. But that's a subjective call
and although I may share the conclusions to help others make a
decision this decision is up to each person to make for themselves.
But, having said that, objective facts are what they are. It's how we
deal with them. Being aware of objective facts and consciously
lowering one's requirements is one thing, but closing one's eyes in
ignorance is quite another.
Don.
Scott W
> Or, as I like to say, context. That's why I step back every now and
> then and ask myself if I'm going too far. But that's a subjective call
> and although I may share the conclusions to help others make a
> decision this decision is up to each person to make for themselves.
ignorance is quite another.
>
> Don.
Don, how can you stay in this thread without posting your image?
You keep going on like you know what you are talking about but as far
as I know
you have not pulled back from your statment that even at the highest
quaility a jpeg image view next to the original will stick out like a
sore thumb.
Why or why Don do you find it imposible to post this image?
Is this really do hard for you?
As long as you maintain that level 12 from Photoshop jpeg have visible
jpeg artifacts it is kind of hard to talk sensibly about lower quality
levels.
Scott
Joe
Oh come on guys give it a rest. He's ignoring you for goodness sake. Do
you really think that calling him a gasbag and full of crap will make
him respond to you now? Hello?
I do not know much about all this but for me he won the moral victory
by taking the high road and I'm more likely to believe him over all
your shouting. I myself don't see any difference but he did say "in
theory" and "to each his own" so why can't you guys leave it at that?
Joe
Scott W
how right he is and how flawed everyone else's images are and why
their examples are not to be trusted.
But what Don will not do is back up his craziness with a single image.
For the record this is what Don wrote
" At 100% magnification (i.e. 1:1) even a JPG image at lowest
compression (i.e. highest quality) stands out like a sore thumb when
compared to the original. "
When Rafe supplied an image that showed this was wrong Don said the
image must not be right, in a rather long winded way.
So just how hard is it for Don to show us just one image that show what
he claims to be true?
Beyond this it kind of brings into question everything else Don has
ever said. Has Don ever once posted an image to back up any of his
claims?
Words are cheap but how do we know if the person spewing them out
really knows what they are talking about? In some cases it is easy,
show us the images that prove what you are saying. In this case how
much easier could be for Don, post a tiff of a crop from one of his
scans that be believes can't be saves as a jpeg without visible
degradation, then it is a simple test to see if it suffers when saved
at level 12 or not.
Scott
Alan Meyer
"Raphael Bustin" <f...@bar.com> wrote in message
news:sqbl4251p9lj47l60...@4ax.com...
> ...
> At 10:1 or 20:1 compression, artifacts will be apparent.
Maybe. Maybe not.
If I magnify the images I can see the artifacts. But when
I look at them at 1:1 magnification, I can't. That is acceptable
to me because I always scan or shoot images at somewhat
higher resolution that I am planning to use, and then view
or print them at 1:1 or, typically, less than that.
Don suggests that I might not see them now on my equipment,
but might see them on a better monitor in the future. He
might be right.
He also suggests that, even though I don't see them now,
I might see them if I trained myself to look for them. He
might very well be right about that too.
But bear in mind that I'm not selling the images I make
or publishing them in books. I'm producing them only for
myself and my family. To me, they look virtually indistinguishable
from images made at lower compressions. I say "virtually"
because it may happen once in a while that I can spot a
detail that's different if I look _very_ closely. In general,
it seems to me that such detail flaws are generally less
significant in image quality than a dust spot on a scan, and
much less significant than an out of focus or motion
blurred region in a photograph.
Maybe I'm not demanding enough. I don't own a high-def
TV. My stereo system is less than the best. When I
painted the walls in my house, I didn't go ballistic if I got
a speck of paint on the floor or the ceiling. My desk is
a beat up thing with chips in it. My computer monitor is not
100% tack sharp in the corners.
Do I need my scans and photos to be not just virtually
indistinguishable from the best scans and photos, but
also actually indistinguishable on the best possible
monitor to the most highly trained eye?
I understand that many of the people who participate in
this newsgroup are professionals. They are selling
services to customers or scanning for employers, and
feel quite rightly obligated to produce the best quality
that they can. The work they turn out may be published
and may be held up for inspection.
But the original poster sounded more like a guy like me,
someone who was scanning for a family archive.
In the photography world, most consumers today are
buying point and shoot cameras at around 5 MP, and
using the default JPEG compression ratios, typically
in the 10:1 - 20:1 range that I'm using. Most of those
consumers are pretty happy with the results they're getting
and wouldn't really be happier with higher quality equipment.
Or at any rate, they're not voting with their dollars, euros
pounds and yen for higher quality equipment.
I suspect that most of those consumers are being pretty
well served by what they're getting - which is how I feel
about what I'm getting.
Alan
Raphael Bustin
wrote:
>
>"Raphael Bustin" <f...@bar.com> wrote in message
>news:sqbl4251p9lj47l60...@4ax.com...
>> ...
>> At 10:1 or 20:1 compression, artifacts will be apparent.
>
>Maybe. Maybe not.
>
>If I magnify the images I can see the artifacts. But when
>I look at them at 1:1 magnification, I can't. That is acceptable
>to me because I always scan or shoot images at somewhat
>higher resolution that I am planning to use, and then view
>or print them at 1:1 or, typically, less than that.
>
>Don suggests that I might not see them now on my equipment,
>but might see them on a better monitor in the future. He
>might be right.
Alan, my argument isn't with you at all.
I'm simply saying that my defense of JPG as
"virtually lossless" extends only to *minimal*
JPG compression.
It's not my business to tell you what the "proper"
quality or compressions are. That's your choice
entirely. No need to justify yourself -- you're using
JPG exactly as it was intended.
Personally, I wouldn't use JPG at all (for important
images) if there were *any* visible image degradation.
At *minimal* JPG compression, I expect virtually-perfect
results. Good enough for high-res scan samples,
in fact.
rafe b
www.terraphoto.com
Joe
Yes he is long winded but he doesn't call people names and sticks only
to his famous facts.
As I said most of that is over my head and his messages always seem to
rub some people the wrong way but I like that he doesn't respond to
provocations and waste bandwidth.
And believe you me your name calling is nothing compared to how others
have tried to provoke him. So that's why I say give it a rest.
Your heckling is doing nothing to him but is only annoying the rest of
us.
> Has Don ever once posted an image to back up any of his claims?
Yes he has many times.
Joe
Raphael Bustin
>As I said most of that is over my head and his messages always seem to
>rub some people the wrong way but I like that he doesn't respond to
>provocations and waste bandwidth.
Joe, are you kidding me? Don's posts are some of the
longest you'll see anywhere on USENET. Full of sound
and fury, signifying nothing.
He responds point-by-point to any criticism, however
slight, to explain with mountains of words that the
fault can't possibly lie in his logic.
What he hasn't shown, in this case, is a single
example to back up his claims. Why do you
suppose that is? How can you defend that?
rafe b
www.terrapinphoto.com
Bart van der Wolf
"Joe" <Joe_N...@hotmail.com> wrote in message
news:1145880862.7...@y43g2000cwc.googlegroups.com...
>> Don is willing to respond over and over with long winded
>> words
>
> Yes he is long winded but he doesn't call people names
> and sticks only to his famous facts.
A lot of his "famous facts" are misinformation, presented as if they
were facts. He may not call people names, but he does insult the
intelligence of several of the regular posters to this newsgroup,
which may become a bit irritating after several years. A kill-file
does help in reducing the irritation, but that won't solve the
misinformation issue for relative "newbies". Be glad that some are
willing to challenge his false claims, otherwise the misinformation
would rule in this newsgroup.
> As I said most of that is over my head and his messages
> always seem to rub some people the wrong way but I like
> that he doesn't respond to provocations and waste bandwidth.
He also doesn't present an example of his JPEGs "sticking out as a
sore thumb" claim. Instead he claims anyone of a different opinion
(even when based on examples) to be "factually incorrect", despite the
evidence presented. Makes "some people" wonder why?
Bart
Bart van der Wolf
>
> "Raphael Bustin" <f...@bar.com> wrote in message
> news:sqbl4251p9lj47l60...@4ax.com...
>> ...
>> At 10:1 or 20:1 compression, artifacts will be apparent.
>
> Maybe. Maybe not.
>
> If I magnify the images I can see the artifacts. But when
> I look at them at 1:1 magnification, I can't.
And that's exacly how JPEG was intended to lose information for the
benefit of more compression, while perceivably maintaining a decent
output quality. Since human vision is more sensitive to luminance than
chromaticity differences, the most sacrifices are made in the chroma
detail. Nothing wrong with that, it's a trade-off by design.
It also means that if image use is repurposed, it would be better to
recreate a JPEG from the original source/data for that different
purpose, rather that mutilate the JPEG any further. Cumulation of
errors may become disturbingly visible quite fast when reprocessing
and resaving is done with JPEGs.
Whether the end result is adequate, is up to the user.
Bart
Scott W
> > Don is willing to respond over and over with long winded words
>
> Yes he is long winded but he doesn't call people names and sticks only
> to his famous facts.
has surly repeated the test that Rafe I and have both done and has
found the same thing we did, there is no visual difference between the
original tiff and the jpeg saved at quality 12.
It would have been a good idea had he don't this test before spewing
out his opinion that the jpeg would stick out like a sore thumb,
nothing like checking your "facts" before putting them out. But he
did not take the time to do this, it takes about 2 minutes BTW.
But instead of modifying his position to something a bit less extreme
when Rafe showed a counter example he simply attacked Rafe's example.
I would say Don has done anything but take the high road here, he is
wrong and he knows is but he is willing at question others methods
rather then admit he was wrong.
Scott
Golden
You're not gonna get him to reply by calling him crazy, that's for
sure.
>When Rafe supplied an image that showed this was wrong Don said the
>image must not be right, in a rather long winded way.
Actually that's not what he said. He just called it unsuitable.
>Words are cheap but how do we know if the person spewing them out
>really knows what they are talking about?
By sticking to facts instead of calling him crazy. But anyway, I don't
wanna get into a brawl with yous guys.
I agree with Joe. It's really sad to try and pick a fight with a guy
who's ignoring you. The more you try the more desperate you look.
So cool it guys. Come on. For our sakes.
Golden
rafe b
"Golden" <golde...@hotmail.com> wrote in message
news:1145894698.7...@i39g2000cwa.googlegroups.com...
> I agree with Joe. It's really sad to try and pick a fight with a guy
> who's ignoring you. The more you try the more desperate you look.
It's a no-win situation at this point.
You're probably right, there's no point addressing
Don any more. He's on the "high road" to nowhere,
as far as I'm concerned. Bon Voyage.
But what to do with Don's misinformation, which
is now on public record? Should we leave it there
for newbies to step into?
rafe b
www.terrapinphoto.com
Joe
>willing to challenge his false claims, otherwise the misinformation
>would rule in this newsgroup.
I do not know who is right and who is wrong because all that is over my
head.
But he does not go on and on trying to pick a fight and provoke someone
who is ignoring him. To me that is a Good Thing.
So even if what you say is true I like much more what he does to what
his many critics do.
But instead of stopping all this I just made it worse so I am going
back to lurking.
Joe
Don
wrote:
>Don's posts are some of the
>longest you'll see anywhere on USENET.
...
>He responds point-by-point to any criticism, however
>slight, to explain with mountains of words that the
>fault can't possibly lie in his logic.
I know it's a very hard concept to grasp, but that's called being
thorough, consistent and respecting every counter point.
Is that short enough for you? ;o)
Don.
P.S. Have you seen any of Kennedy's posts? I'd say that's a good
company to be in if (according to *your* metric) size is all that
matters.
Oh, is that what this is all about? Message length envy? ;o)
rafe b
> I do not know who is right and who is wrong because all that is over my
> head.
Why make that assumption? Why not just try it and see?
There's no need to believe Don, or me, or Scott or Bart.
None of this stuff is rocket science.
What's unfortunate is that you feel this discussion is "over your head."
It's not. The statements made in this thread can be tested
by anyone. All it takes is a few minutes' worth of experimenting -
assuming you already have a computer, monitor and image editor.
I invite you to de-lurk. Try some of the things that folks have
remarked on in this thread, and report back *your* experience.
That would be a real contribution to the group, and you might
learn a bit in the process.
rafe b
www.terrapinphoto.com
Scott W
> On Mon, 24 Apr 2006 09:21:05 -0400, Raphael Bustin <f...@bar.com>
> wrote:
>
> >Don's posts are some of the
> >longest you'll see anywhere on USENET.
> ...
> >He responds point-by-point to any criticism, however
> >slight, to explain with mountains of words that the
> >fault can't possibly lie in his logic.
>
> I know it's a very hard concept to grasp, but that's called being
> thorough, consistent and respecting every counter point.
How can you be thorough and not post an image to back up your claim?
Why do we need to talk about why Rafe's image in not valid?
Why do we need to talk about the theory of jpeg compression?
Why not simply post an image that shows what you believe to be true?
Scott