Color Sampler/Info Palette/ Curves question

[Andymania]

Ok here is some more stuff on my mind. Again I'm trying to decipher some more of Dan Margulis's material. I have been expirimenting with using a 3x3 color sampler and took 4 measurements on a portrait photo. Now, Dan did mention that he takes many sample points before making a curves adjustment, but I'm not sure why. Since, I found out that if I take 1 measurement and find out that that area has to much of a blue cast, chances are that the whole image is too blue. So, I then open up curves, adjust the blue channel and the cast goes away. I don't understand what is the point of multiple color readings since if you get the color right in one reading, the whole picture changes too. Maybe some of you guys can help me with this color correction issue.....

-Andy

[mushmush]

Hello Andy,
I would assume the multiple Color Samplers would reflect light, medium and dark tones. Also neutrals may be separately chosen- not sure.
I'm a lot more familiar with curves in CMYK mode, but possibly the curve (you said the Blue channel curve so I assume RGB) might have to be tweaked to affect certain areas to a greater or lesser degree.
such as: skin tones adjusted to be less yellow but now neutral tones are too purple.
Again- I'm not the best with RGB so take this with a grain of salt.

[redcrown]

The color values in the average face (without a professional makeup job) will vary widely. Not just across the tonal range, but in different areas of the same tonal range. The goal of advanced portraiture is to equalize the colors, so the subject does not have pink cheeks, a yellow neck, and blue eye sockets.

A single 3x3 (9 pixel) sample, followed by a single global adjustment is OK for entry level work, and can cure an obvious global color cast. But multiple samples and multiple masked adjustments will advance the quality significantly.

[Andymania]

Redcrown,

Ahhhh....So it will take several curves adjustment layers with layer masks to really even out tones. I noticed that trying to change all 4 points with one set of curves is impossible, since one curve affects all points simultaneously.

[kav]

Originally Posted by Andymania

Redcrown,

Ahhhh....So it will take several curves adjustment layers with layer masks to really even out tones. I noticed that trying to change all 4 points with one set of curves is impossible, since one curve affects all points simultaneously.

Ugh.. I know you didn't get that idea from me. Adding too many points to a curve can produce weird results. Beyond that, reflections, natural color variation, and lighting make it virtually impossible to adjust all at once. Of course you have to balance how even you want it. Even with professional makeup they vary. If they try to paint the person up to the point where it's just one single color, it can make them look flat, and that still doesn't account for the other things I mentioned.

[andrewrodney]

Originally Posted by Andymania

Now, Dan did mention that he takes many sample points before making a curves adjustment, but I'm not sure why.

Because it is more work?

Since, I found out that if I take 1 measurement and find out that that area has to much of a blue cast, chances are that the whole image is too blue. So, I then open up curves, adjust the blue channel and the cast goes away.

There you go. I guess if you charge by the hour, or if your goal is to make everything more complicated than necessary (to impress, ramble, whatever), then you should NOT be using the process you discovered <g>.

I don't understand what is the point of multiple color readings since if you get the color right in one reading, the whole picture changes too.

KISS is for sissies? If it ain’t broke, don’t fix it.

Or in terms of many complicated techniques some love to use or teach, I’m reminded of one of my favorite quotes from my deal friend, the late Bruce Fraser:

You can do all sorts of things that are fiendishly clever, then fall in love with them because they're fiendishly clever, while overlooking the fact that they take a great deal more work to obtain results that stupid people get in half the time. As someone who has created a lot of fiendishly clever but ultimately useless techniques in his day, I'd say this sounds like an example.Bruce

In the old days (Compuserve Photoforum of the early 90’s) Bruce and Dan would go at it often, it was quite an experience to witness!

[Andymania]

No, no, no Kav, not multiple points on a curve. I'm taking about multiple color reading points with a 3x3 color sampler tool. ex: forehead measures r=a b=b c=c, arm measures r=x g=y b=z........and so forth

[Andymania]

Redcrown did really confirm my thoughts. That I will need multiple curve adjustment layers with different areas masked off to create the uniform tone. I looked at my info palette and at my four color points and noticed that obviously 1 curve will alter all of those 4 values simultaneously and that doesn't work. Are there any other ways you guys might know of that might work as well for such a thing?

I never understood this uniform skin trend. Human skin usually has all sorts of variations of hue. Usually the same saturation( not including red cheeks or people with skin issues).
But all sorts of variations..........oh well. I'll do what is in demand I guess.

Andrew, thanks for the feedback.

[andrewrodney]

Originally Posted by Andymania

Are there any other ways you guys might know of that might work as well for such a thing?

You could try Selective Color after using Color Range (and even with a sloppy selection first around differing areas). CS6 has a new option for dealing specifically with skin in Selective Color that is decent.

I really wish Selective Color and Color Range were one tool!

[redcrown]

Three other ways...

1. Gradient Maps. A Gradient Map adjustment layer in "HUE" or "COLOR" mode, where the gradient has 2 or three points set to the desired skin color at the tone point on the map. Gradient Maps are a bit complicated and can be hard to understand at first. But the technique can do a good job of evening out skin color.

2. Using "color map" masks on a normal Curves adjustment to restrict the curves adjustment to areas where it is needed. In other words, use a mask to find areas that have excess Yellow (or Magenta) and apply that mask to a Curves adjustment that bends the Blue or Green channel curve.

Here is one way I do that:

2a. Make a dupe of the image and convert it to CMYK mode.

2b. Run Calculations and create a new channel by subtracting the Yellow channel from the Magenta channel. That will give you a faint and harsh channel mask. So apply a Levels adjustment to it to increase contrast and Gaussian blur it to reduce the harshness. That will give you a mask showing where Magenta exceeds Yellow.

2c. Copy that mask back to the original and add it to a Curves adjustment layer. Go to the Green channel in Curves and drag the center point up and to the left. That will reduce Magenta and the mask will restrict the reduction to areas where Magent exceeds Yellow. Use the amount of the curve and/or opacity on the Curves adjustment layer to control the amount of reduction.

2d. Do it again, but in the CMYK copy subtract Magenta from Yellow and use that mask on a Curves adjustment that pulls the Blue channel up and left, reducing Yellows only where they exceed Magenta.

3. Simply paint with color. Add a blank layer, set the blend mode to Color and opacity to about 20%. Use a soft brush, sample a good color and paint over a bad color. When you paint a color over itself, nothing happens. Kind of like an automatic mask. So, you can sample a good color from a cheek, chin, or forehead, and then paint around the eye sockets. If your painting strays into the cheek, no problem because you are painting a color over itself. Likewise, sample a good cheek and paint over a sunburned nose.

This method does not always work well because painting one color over another color actually creats a third color. If the first two colors are far apart, the result may not be good. But if they are close, the result may be OK. However, it is the quickest and easiest method.