setting an image white point
Kerry Pierce
select a point in an image that is known white/grey/black. Selection of a
known point with one of those droppers will then automatically adjust the
rest of the colors in the image.
I'm trying to figure out how to do that in PSP 7.04, but can't find a
way. I'd appreciate any info on the why's and howto's.
Thanks!
Uni
You might try the Histogram Adjustment. This is where you'd set the
black and white points in a image. You can find it under the Colors drop
down menu.
Uni
>
> Thanks!
Kerry Pierce
Thanks Uni, but that doesn't do quite the same thing. For instance, if
you have a photo with a guy in a white shirt, you touch the white shirt
with the eyedropper, which tells PS that the shirt color is white and it
adjusts the rest of the image accordingly. For digital photos, the camera
will set the white balance for each exposure. Some times, it is an
incorrect setting, which will leave a color cast, especially on an
underexposure. I presume this would also happen with scanned images.
Dunno, my scanners are still in the box, waiting for the day when I have
the time to set them up... :-(
I can correct the problem with PSP's various tools, but it requires quite
a few steps and I just wondered if I am doing it the hard way. PS's levels
eyedropper is pretty much a one-click fix for this problem. I'm just kind
of a hard head, cuz I'd rather use PSP...
Uni
Kerry Pierce wrote:
>
> Uni <plg...@usa.net> wrote:
>
> >>> In PS, in adjusting Levels, there are 3 eyedroppers that allow you to
> >>> select a point in an image that is known white/grey/black. Selection of a
> >>> known point with one of those droppers will then automatically adjust the
> >>> rest of the colors in the image.
> >>>
> >>> I'm trying to figure out how to do that in PSP 7.04, but can't find a
> >>> way. I'd appreciate any info on the why's and howto's.
> >>
> >>You might try the Histogram Adjustment. This is where you'd set the
> >>black and white points in a image. You can find it under the Colors drop
> >>down menu.
>
> Thanks Uni, but that doesn't do quite the same thing. For instance, if
> you have a photo with a guy in a white shirt, you touch the white shirt
> with the eyedropper, which tells PS that the shirt color is white and it
> adjusts the rest of the image accordingly.
The Histogram adjustment should do that as well, Kerry. I sometimes use
the "dropper" to detect actual white and/or black points in a image.
Unfortunately, you can do this simultaneously while using the Histogram
adjustment. If I ever get a color cast due to any adjustment or scanner
quirk, I use the Color Balance (non automatic) and Dropper to
reestablish the purity of white, black, and mid points, if there's such
a thing :) Digital cameras and scanners aren't perfect. This is why we
need software to give the images that final touch-up.
There will never be any graphics software which will automatically make
any image look it's best. Software lacks two things, eyes and a human
brain :)
Anyway, maybe someone else here can help you along.
Uni
P.S. Try some of the Automatic Photo enhancement tools in PSP 7. They
work well.
Rick Simon
news:r9rb6uo6dm3jrtta7...@4ax.com:
> Uni <plg...@usa.net> wrote:
>
>>>
>>>You might try the Histogram Adjustment. This is where you'd set
>>>the black and white points in a image. You can find it under the
>>>Colors drop down menu.
>
> Thanks Uni, but that doesn't do quite the same thing. For
> instance, if
> you have a photo with a guy in a white shirt, you touch the white
> shirt with the eyedropper, which tells PS that the shirt color is
> white and it adjusts the rest of the image accordingly.
You might try using Effects:Enhance Photo:Manual Color Correction.
In the dialog box, select a small area in the preview image on the
left that you know is supposed to be pure white, then set the Color
Category to Pure Colors and select White from the Preset Colors. You
can also use the Preserve Lightness and Preserve Saturation options
to help get the right overall effect on the image.
--
Rick Simon
rsi...@cris.com
Kerry Pierce
>>> Thanks Uni, but that doesn't do quite the same thing. For
>>> instance, if
>>> you have a photo with a guy in a white shirt, you touch the white
>>> shirt with the eyedropper, which tells PS that the shirt color is
>>> white and it adjusts the rest of the image accordingly.
>>
>> You might try using Effects:Enhance Photo:Manual Color Correction.
>>In the dialog box, select a small area in the preview image on the
>>left that you know is supposed to be pure white, then set the Color
>>Category to Pure Colors and select White from the Preset Colors. You
>>can also use the Preserve Lightness and Preserve Saturation options
>>to help get the right overall effect on the image.
Yes, this is pretty much what I was looking for, thanks! With a color
cast image, I had to deselect the Preserve Saturation option.
I never realized what a good tool that is and I really love the preview
windows!! They're twice the size of the other tool's windows. I can
actually see what's going on with the image without having to look at the
original. That is way cool. :-) This tool is going to find a new home on
the toolbar next to Clarify and Unsharp mask.
Hey Kris, any chance that the other tools previews could be sizeable or
something to the same size as the Manual Color Correction in the next
version? heh. :-)
Mitch
news:5r2c6u8ud51q28f0b...@4ax.com...
> Rick Simon <rsi...@cris.com> wrote:
> >> You might try using Effects:Enhance Photo:Manual Color Correction.
> >>In the dialog box, select a small area in the preview image on the
> >>left that you know is supposed to be pure white, then set the Color
> >>Category to Pure Colors and select White from the Preset Colors. You
> >>can also use the Preserve Lightness and Preserve Saturation options
> >>to help get the right overall effect on the image.
>
> Yes, this is pretty much what I was looking for, thanks! With a color
> cast image, I had to deselect the Preserve Saturation option.
>
I'm not sure it really does the same thing as using the Droppers in PS
Levels Adjustment.
If I recall correctly, Kris once commented here on this particular PSP tool
and he indicated that it corrects the selected color but it does *not*
uniformly correct the entire image based on that color (unlike the PS
Dropper tool).
Kris, if you see this, can you comment? Is the PSP Enhance Photo|Manual
Color Correction the equivalent of the White-Point Dropper in Photoshop?
Kris Zaklika
Mitch, first of all Manual Color Correction is not the
exact equivalent of the White-Point Dropper in that expensive
program. However, we have to be a little careful here in
what we say. For example, suppose that we have an image in
which a pixel that is supposed to be black is black but a
pixel that is supposed to be white is not exactly white.
(We can say it's bluish, for example, but this detail is not
important.) When you set this pixel to the white point in
PS the color of that pixel is moved all the way to white
but the color of the black pixel is unaffected. Therefore,
the image is not corrected uniformly, since a large correction
is applied to colors near white, a moderate correction for
midtone colors and a negligible correction for dark colors.
So, your comment that PS "uniformly correct[s] the entire
image" is not quite correct. Manual color correction has
a similar behavior in that it corrects the selected color
to exactly the specified color, and the remaining colors
are modified to a smaller and smaller degree the more
different they are from color being exactly corrected. In
some ways this is a more powerful filter than the one in
PS because it can work with any color, not just a white
point or a black point. However, because it works differently
from the PS droppers you may have to cycle between setting
the white point, then the black point, then the white point
again, then the black point again, and so on. Each successive
correction will have a smaller and smaller effect. In some
tests I did three corrections at each point were enough to
achieve a result where the image no longer changes perceptibly.
The need to do this cycling is related to the fact that the
filter is biased towards handling chromatic colors more
than achromatic colors such as black and white. It is not
that the filter doesn't work with achromatic colors; it is
simply less efficient at shifting them than it is for
chromatic colors. To achieve good leverage on the color I
would use a portion of the image that has colors around 235
for highlights and 30 for shadows in doing the correction,
keeping Preserve Lightness checked to prevent contrast
changes during color correction.
With all that said, I have to mention that Automatic Color
Balance does all this white-point, black-point stuff
automatically. By playing with the Strength and Remove
color cast settings you indirectly change the definitions
of the white and black points. I'd be surprised if you
couldn't achieve results similar to those obtained with
the PS droppers, especially if you consider that you can
specify a white with Manual Color Correction beforehand.
However, in saying this I don't deny that droppers can be
useful tools in experienced hands.
--
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