[alt-photo] Tricolor printing/Photoshop

[Marek Matusz]

 All, I am having a mental block. I know somebody posted it before, but I just can't come up with it. I would like to display on the screen a 'simulation' of RGB gum printing. That is to take for example R channel and colour it cyan, then take G channel colour it magenta and combine with the previous layer to display effect of the two layers printed together, etc. Marek