Importing Tokens with RGB Color Overlays

Hi everyone, I am building a puzzle and am trying to figure out if there is a way to do it in Roll20.    The players will have a set of green, red, and blue gems that cast light through prisms. Part of the puzzle requires them to mix the light from their gems to make the secondary colors (like yellow, magenta, and cyan).  I can create this effect in photoshop using the exclusion blending option but have not found a way to maintain that setting in the export options. I've tried exporting the layers as transparent pngs, but they don't mix correctly (red and green make a brown for example).   Was just wondering if any of you folks had any ideas on how to make this work. Thanks for your time! :)

You won't have any control over the type of blending of images on the table top in Roll20.  Probably it's the equivalent of screen, but Keith will probably come correct me. =D You might be able to achieve the effect you want using colored auras on the tokens, but that's just speculation and another direction to look into.  You may be able to get something close to what you want with some old school interleaving, but the quality may not be what you are after and scaling and compression may break it for you.

I haven't tested this effect on Roll20, but I believe a PNG saves only a vanilla alpha channel to control transparency (no darken or overlay or soft light or similar transparency modes). Therefore, I'm not sure if what you are trying to accomplish is possible outside of a graphics program. However, look in the free module The Master's Vault. There is a similar puzzle which uses a red-blue effect (the interleaving that Aaron spoke of?) that might achieve the goal you are going for if not the method. You might be able to glean something from that method. The Master's Vault is available on any Create a New Campaign page.

Awesome, thanks guys! I'll look at the Master's Vault and see what they did there.  I did try and achieve the effect using auras, but ran into the same problem I did with the transparencies (muddied colors rather than true RGB screening). 

Another good place to look is in the Stupid Tricks thread: Aura Effect to Reveal Hidden Objects or Markings  - reported by Gold ( Stephen S.'s original thread )

I'll give that a shot, thanks! :)

Would it work to tint a transparent PNG token?