Black and White with Selective Colors

I’m trying to recreate the look of where the entire screen is in black and white but some elements can be seen with color (like the girl in Schindler’s List or Sin City). I did post processing volume to get the black and white feel but how do I get color back into select objects?

The black and white effect I’m getting so playing weird with lights (desaturate, high contrast @ 2 (XYZ), gamma @ 0.5 (XYZ), low gain, crush shadows and highlights @ 1, bloom @ 4). Is there a better way to achieve a black and white effect? Is there something like levels in PP-volume?

Ok got it working with blendables and a custom depth mask but problem now is that the colored objects can be seen through black and white geometry. Is there a way to not allow rendering through other objects?

Nvm got it all working, used a scene depth comparison and got it working. Lighting in black and white still messed up though.

I’m not familiar with whether or not UE4 has an automatic way of doing B&W. But I’ve found doing the same as gimp, by using a weighted average of the RGB values to get your greyscale value to be good!

They use 0.21 R + 0.72 G + 0.07 B. So in your postprocess material you’d use that formula to average scene color and it would give you the value for one channel of your output color, hope that makes sense. I’m at work so I can’t look at the material editor.