How to replace a color with one I exactly want

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Let’s say my skin is too yellowish and I want to replace it with the more pinkish one of a young beautiful girl I find in another picture. How can I do it? Thx.

Method 1) Measure a target RGB value, set up an eyedropper sample point on your final image, and then use curves to achieve your desired RGB value. Your adjustment will consist of adding red and/or removing green. You may get a better result by using an HSB target value, and matching the Hue and Saturation values.

Method 2) Measure the RGB value as before, and use selective color to add magenta to red, or subtract green, until you reach the RGB or HSB value you want.

Method 3) If you are on Windows, you can use Curvemeister’s color pinning feature. This is an automated version of Method 1, where Hue and Saturation are set to nominal skin values, and where the best color space may be easily chosen.
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Mike Russell
www.curvemeister.com/forum/

Method 2) Measure the RGB value as before, and use selective color to add magenta to red, or subtract green, until you reach the RGB or HSB value you want.

According to Color Picker, the pinkish color I want has these values: H 20 S 37 B 92 L 77 a 19 b 23 R 234 G 177 B 148 #EAB194. But Selective Color provides ways to only increase or decrease a color by a certain percentage.
So how do I translate those absolute values into the %s?

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Method 2) Measure the RGB value as before, and use selective color to add magenta to red, or subtract green, until you reach the RGB or HSB value you want.

According to Color Picker, the pinkish color I want has these values: H 20 S 37 B 92 L 77 a 19 b 23 R 234 G 177 B 148 #EAB194. But Selective Color provides ways to only increase or decrease a color by a certain percentage.
So how do I translate those absolute values into the %s?

The HSB color model will probably the most useful for this, and modifying the amount of magenta, green, and cyan in red will allow you to zero in on the Hue and Saturation value you want.

Place an info "eyedropper" on the original yellowish skin tone, and set it to read HSB. Since your target color has more red in it, add magenta to red, or subtract green from red to get the desired Hue angle of 20 degrees. The saturation and brightness may also be changed by altering the amount of cyan in red.

There are other methods than selective color. CMYK is a good color space for fine adjustment of skin tones with curves, since it offers fine control over magenta and yellow.

If you’re going to do this very often, consider using the pinning feature of Curvemeister, which automates the process of setting a skin tone to a desired Hue and Saturation value.
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Mike Russell
www.curvemeister.com/forum/

1. Correct me if I am wrong. I think the procedure would involve
mapping the color of a particular pixel in my yellowish photo to the color of a particular pixel in a pinkish photo, and using it as a ‘baseline’ to map the color of other pixels in (the selected area of) my yellowish photo relative to the selected pixel.
2. Let’s say I select a pixel in the pinkish photo and somehow measure its values: H 20 S 37 B 92 L 77 a 19 b 23 R 234 G 177 B 148 #EAB194. Now EXACTLY how do I select a pixel in the yellowish photo and map it to these particular values? And as I said, the Selective Color dialog box appears to allow one to add color by a percentage. But why would anybody adjust it by trial and error by sliding along the bars, adding red, subtracting green, and so on, if he knows the exact color values he wants? How come there is nothing in Photoshop that allows me to select a pixel and say ‘I want the color of this pixel to be R 234 G 177 B 148 and adjust all other pixels relative to this pixel’?

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1. Correct me if I am wrong. I think the procedure would involve mapping the color of a particular pixel in my yellowish photo to the color of a particular pixel in a pinkish photo, and using it as a ‘baseline’ to map the color of other pixels in (the selected area of) my yellowish photo relative to the selected pixel.

You’ve obviously put a lot of thought into analyzing the problem and coming up with a solution. This has the problem that it becomes hard for others to tap into your train of thought and come up with a suggestion.

The process you describe is called "color pinning" in curvemeister. More generally, if you use curves or another method to match a particular color to a target value, the rest of the image will follow suit. This is a standard way to remove a color cast.

2. Let’s say I select a pixel in the pinkish photo and somehow measure its values: H 20 S 37 B 92 L 77 a 19 b 23 R 234 G 177 B 148 #EAB194. Now EXACTLY how do I select a pixel in the yellowish photo and map it to these particular values?

Create an eyedropper sample point over the source color, and perform your adjustment until the numbers match your target values.

And as I said, the Selective Color dialog
box appears to allow one to add color by a percentage. But why would anybody adjust it by trial and error by sliding along the bars, adding red, subtracting green, and so on, if he knows the exact color values he wants? How come there is nothing in Photoshop that allows me to select a pixel and say ‘I want the color of this pixel to be R 234 G 177 B 148 and adjust all other pixels relative to this pixel’?

This would be a desirable feature, and it is implemented in the Curvemeister plugin. Photoshop’s sample values are read-only, so it is necessary to make the adjustment and observe the color samples manually.
—

Mike Russell
www.curvemeister.com/forum/

…perform your adjustment until the numbers match your target values.

What numbers? Where can I see the "numbers"? My problem has been that I am not able to see any absolute values of the colors, as adjusted, in my target photo. For example, the Selective Color dialog box shows a few sliding bars and I can adjust the colors by sliding along the bars and it also shows 10%, 20%, etc next to the bars (I have no idea what those percentages mean – I mean, percentages of what?), but there is no absolute values that says "OK, now Red’s number is now 234, Green’s value is 177, etc" so that I know I get the individual color channel of the target photo match my desired value. Are the "234 177 148" what you mean by "numbers"? How do I know whether I have reached the desired values?

…it is necessary to make the adjustment and observe the color samples manually.

What do you mean by "manually"? pixel by pixel?

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…perform your adjustment until the numbers match your target values.

What numbers? Where can I see the "numbers"? My problem has been that I am not able to see any absolute values of the colors, as adjusted, in my target photo. For example, the Selective Color dialog box shows a few sliding bars and I can adjust the colors by sliding along the bars and it also shows 10%, 20%, etc next to the bars (I have no idea what those percentages mean – I mean, percentages of what?), but there is no absolute values that says "OK, now Red’s number is now 234, Green’s value is 177, etc" so that I know I get the individual color channel of the target photo match my desired value. Are the "234 177 148" what you mean by "numbers"? How do I know whether I have reached the desired values?

Place an eyedropper sample value on the area whose color you wish to adjust. The sample tool is accessed by clicking and holding the mouse button. You can create up to four sample points whose values will show on the info palette.

…it is necessary to make the adjustment and observe the color samples manually.

What do you mean by "manually"? pixel by pixel?

I agree that pixel by pixel would certainly be absurd, and if I have implied that you should do this, I apologize for my rudeness. Adjust the controls until you see the value you want in the info palette.
—

Mike Russell
www.curvemeister.com/forum/

In my last post "clicking and holding the mouse button" should have said "clicking and holding the mouse button on the eyedropper icon in the tool palette".
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Mike Russell
www.curvemeister.com/forum/