Color Photo to Grayscale Converter
Mark Franzels
Are all color to grayscale converter algorithm the same? Or are there
many different levels of qualities to it like scanning or printing?
But then
in converting color to grayscale, perhaps there is
a simple formula that is used by all software,
hence the same quality in all except differences
in brightness or contrast which you can adjust
in photoshop?
Mark
Me
Adjustments are made to RGB channels separately before desaturation,
effects much like using a yellow filter with mono film (darkening blues
to bring out clouds) etc.
A problem with converting by just desaturating to greyscale, then making
contrast adjustments, is getting smooth gradations, as greyscale has
only 255 levels in an 8 bit image file, so integer rounding can easily
cause posterisation / banding. I prefer to work with the raw file for
monochrome conversion. I guess an alternative would be to work on an
image file in 16 bit colour space in photoshop.
Bob Larter
Same here.
> I guess an alternative would be to work on an
> image file in 16 bit colour space in photoshop.
That's how I do it. I always convert my RAW files to 16 bit (actually 48
bit) PhotoShop files, rather than 8 bit (actually 24 bit) files for that
reason.
--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------
ray
No - not the same. There are many ways to convert from color. As I
recall, there is a GIMP plugin with about 27 different variations.
Mark Franzels
Where can I download it and integrate it in photoshop?
But what I was asking was whether the "Change to Grayscale"
functions in all graphic programs work the same before
you edit them with special gimp plugin. I used different
programs and convert a reference photo to grayscale,
there seems to look the same but not sure. So what
is the best program with best default for changing
color to grayscale?
Mark
Bob Larter
> On Apr 12, 2:38 am, ray <r...@zianet.com> wrote:
>> On Sat, 11 Apr 2009 00:56:14 -0700, Mark Franzels wrote:
>>> Hi,
>>> Are all color to grayscale converter algorithm the same? Or are there
>>> many different levels of qualities to it like scanning or printing? But
>>> then
>>> in converting color to grayscale, perhaps there is a simple formula that
>>> is used by all software, hence the same quality in all except
>>> differences in brightness or contrast which you can adjust in photoshop?
>>> Mark
>> No - not the same. There are many ways to convert from color. As I
>> recall, there is a GIMP plugin with about 27 different variations.
>
> Where can I download it and integrate it in photoshop?
No need. PhotoShop comes with the Channel Mixing tool, which gives you a
near infinite variety of ways to convert colour to greyscale.
> But what I was asking was whether the "Change to Grayscale"
> functions in all graphic programs work the same before
> you edit them with special gimp plugin. I used different
> programs and convert a reference photo to grayscale,
> there seems to look the same but not sure.
Most programs convert to greyscale by reducing the colour saturation to
zero, so most programs will give you a similar-looking result. (You can
do it that way in PhotoShop too.)
> So what
> is the best program with best default for changing
> color to grayscale?
"How long is a piece of string?"
The answer is that it depends on what result you're trying to achieve.
If you just want a generic result, just reduce the saturation to zero in
whatever program you prefer.
ray
I certainly can't say what program is 'best' for you. For me, the most
flexibility would be 'best'. I admit I don't use photoshop - I use GIMP -
you can download and start using it for free - there are a lot of plugins
available. I've also seen some good descriptions of the different methods
used and the different 'moods' they produce. It was either in 'Grokking
the Gimp' which is downloadable from the internet, or in the book
'Beginning GIMP'. You will get quite dramatically different 'moods' by
processing to greyscale in different ways.
If it's not clear, GIMP is a completely free, stand alone photo editor.
It has many of the same capabilities as photoshop. See www.gimp.org.
nospam
<bobby...@gmail.com> wrote:
> >>> in converting color to grayscale, perhaps there is a simple formula that
> >>> is used by all software, hence the same quality in all except
> >>> differences in brightness or contrast which you can adjust in photoshop?
> >>> Mark
> >> No - not the same. There are many ways to convert from color. As I
> >> recall, there is a GIMP plugin with about 27 different variations.
> >
> > Where can I download it and integrate it in photoshop?
>
> No need. PhotoShop comes with the Channel Mixing tool, which gives you a
> near infinite variety of ways to convert colour to greyscale.
photoshop also comes with a black & white converter tool just for this
purpose. plus there are zillions of other ways to do it too. russell
brown has a few tutorial videos with a number of tricks.
Ron Hunter
programs has a very steep learning curve. Be prepared to spend some
quality time learning even the most basic techniques.
ray
I've found 'most basic techniques' to be pretty intuitive. Simply look
through the menus and you'll see a lot of meaningful entries. The
downloadable 'Grokking the GIMP' is a good tutorial for going a little
'in depth'. Just my opinion - YMMV.