What are the technical details that make turning black skin to white difficult?

[PSKer]

I am not that advanced in my editing skills. But I can change the color of a dress, replace the head, correct a skin tone and texture, remove lens flare, and stuff like that.

I have been trying to find an easy and straightforward way to turn black skin into white, but couldn't understand why technically there doesn't seem to be an easy way. I mean what in the color details that make this look impossible given the advanced tools we have in photo manipulation programs like PS.

Among what I tried is using a gradient map layer putting the desired color in the middle and moving the slider to the left. I tried putting the desired color on the left. I tried the colorize option in hue/sat. layer. I tried solid color layer with hue and color blending modes. I tried curves layer to brighten the skin first and then applying a gradient map, hue/sat. or solid color layers.

I also tried extracting the white skin color from the black skin color, and then adding the extracted color over with a linear dodge (add) blending mode.

Nothing worked.

I have no other purpose, but I'm curious, what is it in the color details that make turning black skin into white such a complete job?

[didiermazier]

hard to say without seeing the pic ture you want to edit…

BTW Black is Beautiful!

[PSKer]

I agree black is beutiful. I am trying to understand the art and the technical details.

[PSKer]

This is an example.

[c.pfaffenbichler]

As @didiermazier already mentioned please post a sample image (or more) and screenshots with the pertinent Panels (Toolbar, Layers, Options Bar, …) visible of the attempts you were dissatisfied with. 

Feel free to crop them to the pertinent areas. 

Do you work with RAW images? 

Is the problem the overall appearance or (in part) the masking? 

[PSKer]

At the moment I'm not working with RAW images. And there is no problem with the appearance. Recently I edited a photo of my black friend (without having to change her skin color), and she was impressed with both the outcome and my humble skills.

I am just curious and want to now why.

[PSKer]

I've attached a sample file above.

[D Fosse]

Basically the luminance is different, which changes the whole tone response curve. That quickly gets tricky, especially for subtle skin tones. The color in itself is the least problem.

[PSKer]

I didn't get you. Can you explain it for a newbie?

[Lumigraphics]

I don't think I would even try that. And I'm pretty experienced with Photoshop.

[PSKer]

I'm not sure why you wouldn't. But my purpose is to find out why it isn't easy or straightforward, and if it is, I want to know. It's a matter of curiousity.

[Lumigraphics]

I wouldn't because I suspect that its technically pretty close to impossible. The tonal map will be completely different. As a very experienced pro, I can tell you that you have to account for skin tone when lighting a portrait subject.

[PSKer]

Can you explain your point in a simpler way that a little experienced newbie can understand?

[Lumigraphics]

Lighter. Skin. Tones. Are. Mostly. Orange. Not sure how to make that easier to understand.

[PSKer]

See about which answer of you I was asking. I didn't ask about whether the white skin is orange or some other color. You mentioned orange in another reply to someone else. Are you OK?

[Lumigraphics]

Are you ok? And with that I'm out.

[Conrad_C]

Lighter. Skin. Tones. Are. Mostly. Orange. Not sure how to make that easier to understand.

By @Lumigraphics

I think the issue is that it’s more than just about what color to change it to. It’s also about how to change it, which technique, what steps to follow. A traditional single move with Curves or Levels will not do it, because of how dark the original hand is. So a more advanced color changing technique must be used, and that is ultimately what was missing from our answers until I remembered the tutorial video I posted in my reply.

[c.pfaffenbichler]

In any case with such a strong Adjustment it may be necessary to decontaminate the edges for the edited element and the »background« separately. 

[Conrad_C]

The difficulty may have to do with understanding the color value proportions  for “black” and “white” skin tones. I put those in quotes to emphasize that they’re not pure black or white. Of course you know that already, but my point is, making it convincing depends on ending up with skin tone values within an expected RGB or CMYK color range for the specific ethnicities you’re working with.

I’m not an expert on what those color values are, I just know that for example, some prepress photo technicians with many years of experience know in their heads what CMYK color values to aim for when editing human skin tones. I think I also read somewhere that the main difference between “white” and darker skin tones was the amount of cyan. So what you probably want to do is some research into the target RGB or CMYK color values that are generally recognized in the portrait/retouching industry for various ethnicities, and use the color monitoring tools in Photoshop (such as the color samplers and Info panel) to make sure you are guiding your skin tone colors into that range.

[Lumigraphics]

Lighter skin tones are mostly orange.

[PSKer]

I haven't mention any color name. Have you seen the sample psd file that I attached above?

[Conrad_C · Accepted solution]

I haven't mention any color name. Have you seen the sample psd file that I attached above?

By @PSKer

No color name is needed. I looked at the layers in your file, and you may want to try a different approach. I started over with your base layer, and got the results below. I based this on a simple color-changing technique that you can learn in the Photoshop Training Channel tutorial video at the end of this post. That technique uses just two layers: A Solid Color Fill layer set to Color blending mode, and a Levels adjustment layer used only to remap the tones. Both are masked to the dark hand through a layer group mask. I tried to achieve more control by replacing the Solid Color fill layer with a Gradient Map layer, and by replacing Levels with Curves. I wanted to see if adding color stops to the Gradient Map would provide more color variation from light to shadow.

For this example it wasn’t necessary to know what the color value numbers should be…I simply sampled the color from the light skin, and that set the initial target values.

In my version, the mask edge where the two hands meet does not look good because I didn’t spend much time on that part. You might also want to retouch the areas on the light hand that were near the original dark hand, because the now lighter skin should reflect more light on the hand on the right.

 

[PSKer · Accepted solution]

Great job and thank you for sharing the tutorial. I still haven't good results as good as yours. But I'll try again some other time.

[davescm]

In terms of Hue both skin colours are remarkably similar. What varies is the luminance and saturation. This is the principle of the skin tone line on a vectorscope (commonly used in colour grading video). Your difficulty, leaving aside ethical issues, will be adjusting the luminance and saturation ranges (there is no single value or single range) to look natural whilst leaving hue unaffected.

https://larryjordan.com/articles/color-correction-make-people-look-normal/

https://creativecloud.adobe.com/cc/learn/premiere-pro/web/correct-skin-tones

Dave

[PSKer]

I've been studying the articles you gave me. They are very informative and I appreciate that you've given them to me. But they are irrevant to what I'm asking.