Color channel subtraction/manipulation

Hi there,  I just wondered if there is a way to get color channels of a layer and perform operations on those. For example, to subtract (or add) the green channel from the red channel to get something like a Color Difference Mask that can be used as a basis for easier rotoscoping in Mocha.

I know about the RGB channel viewer in the Viewer window, but it is probably not suited for that purpose.

Does anyone have a hint for me how to perform this?


  • Triem23Triem23 Moderator Moderator, Website User, Ambassador, Imerge Beta Tester, HitFilm Beta Tester Posts: 18,275 Ambassador

    Channel Mixer and Channel Swapper effects in Channel Effects group? 

  • MartyVivMartyViv Website User Posts: 7

    Thanks, Triem23. Yeah, I stumbled upon these two, too. What I was trying to find is an effect that takes the greyscale representation of a color channel and allows me to use blend modes (Subtract, Add or Multiply, for example) to mix them. In the end, the result should be a matte ready for further steps.

  • RobinRobin Website User, HitFilm Beta Tester Posts: 1,671 Enthusiast
    edited January 2015

    Well, you can use the channel swapper to get this kind of matte - just set all the drop-downs except alpha to one of the channels and you get a black-and-white image of the color channel you chose, and can work with that as a matte from there on. Blend modes then just work like with any other layer.

  • MartyVivMartyViv Website User Posts: 7

    Thanks for your help, Robin!

Sign In or Register to comment.