白平衡（色彩抑制）公式？ [英] White balance (Color Suppression) Formula?

问题描述

我需要帮助一点颜色数学（RGBA）我试图减少一个字符的绿色量，而实际上不影响绿色背景。绿色屏幕的视觉效果。

I need help with a little bit of color math.(RGBA) I'm trying to reduce the amount of green on a character, without actually affecting the green background. Green screen for visual effects.

这里是我有：

我有一个家伙在绿色屏幕上。

I have a guy on green screen.

使用表达式： g>（r + b）/ 2？ （r + b）/ 2：g
表达式表示如果绿色值大于红色和蓝色之和除以2，那么绿色将被设置为该和。运行该表达式将给我第二个图像。
你可以看到，绿色被完全从人，我想要的，但它也采取绿色的背景，使它的灰色，我不想要的。

Using the expression: g>(r+b)/2 ? (r+b)/2:g Expression says if the green color value is greater than the sum of red and blue divided by 2, then it green will be set to that sum. Running that expression will give me the second image. You can see that the green is removed perfectly from the guy, which I want, but it also takes the green from the background and makes it gray, which I don't want.

此图片显示的是绿色删除。我得到这个从第二个减去第一个图像。所以它的两个区别。

This image here is how much green is removed. I get this by subtracting the first image from the second. So its the difference between the two.

有人可以帮我找出我的方法只能通过表达式/公式从家伙而不是背景中删除绿色？我试图钳制绿色，意思，写一个表达式，说：对于低于一定值，不等于背景绿色的任何绿色像素，将其变黑。这有点工作，但它的非常苛刻的细边上的头发。

Can someone help me figure out how I can only remove the green from the guy and not the background via an expression/formula ? I have tried to clamp the green, meaning, write an expression that says: for any green pixel thats below a certain value that not equal to the background green, turn it black. This kinda works, but its very harsh on the fine edges like that hair.

下面是我通过进行大量的颜色校正和分级所实现的所需结果。我想通过表达式获得这个结果。

Below is the desired result which i achieved by doing a lot of color correction and grading. I would love to get this result via expression.

这里是最终结果。看起来不错。这个图像是绿色从字符，但不是背景。我得到这个，通过添加上面的图像到第二个图像。我做了一个拆分屏幕，所以你可以看到差异。

and here is the final result. it looks great. This image is the green gone from the character, but not the background. I got this by adding the image above to the second image.I did a split screen so you can see the difference. mostly visible in the jacket and hair.

推荐答案

感谢大家的想法和想法。每个评论都是一个火花，让我来，我认为，最接近解决方案。
它需要更多的工作。如果你仔细看看他的拳头，你可以看到它打破abit。下一步是建立可调节的值来影响效果的重量。

Thankyou everyone for your thoughts and ideas. Every comment was a spark that led me to, which I think is, the closest to a solution. It does need more work. If you take a closer look at his fist, you can see it break abit. The next step for this is to build in adjustable values to affect the weight of the effects.

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