Gray Backgrounds for Flipbooks

I know this is a very basic question, but other than rendering out a fume render with a gray background… is there a way to take an existing sprite sheet and replace a black background with a more useful/neutral gray background?

I’ve done screens in photoshop, and even used an alpha mask on the color, but it always alters the image slightly.

Thanks for any help.

I don’t know what software you have access to, but look into unpremultiplying/predividing. It usually does the trick.

Using photoshop and after effects

Apparently there is a way to do it in AE even though it doesn’t have a built in function for it.

Check this out: finthrow vfx blog: How to do a Divide operation in After Effects

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I’m not even sure I can follow that… is there something you use that is basically just a “tool” to do it?

Thanks for the help.

Well, I render my stuff out with houdini. Houdini has a compositor built in so I simply drop in a premult node and set it to divide. Done.

Don’t know if there are any standalone tools that do it. Sounds like something Slate should look into @alex.underhill :stuck_out_tongue:

Ok cool thanks man :slight_smile:

:sweat:I hate premul stuff.
But, it does have a premul function to change background colour of textures when imported.
Annoyingly no software ever saves premul as a “thing” so once exported, there’s no way to change it. I got around this by looking at the alpha channels in a special way. Seems to work pretty well, but I’ll be using that divide op when I can!

Yeah I tried the method, but the result was less than stellar, it’s easier to just interp the footage as premul and then just add the gray background as a layer beneath it


There’s quite a few ways to do it in After Effects. My preference is Color Vibrance (free from VIDEO COPILOT | After Effects Tutorials, Plug-ins and Stock Footage for Post Production Professionals), you can also try Knoll UnMult.

Also when rendering out from After Effects, you can either use premultiplied or straight alpha depending on what you need.


dilateerode node in houdini… even better than just background… Recently I almost forget my password to photoshop…

Just make procedural atlas with mosaic node. Then use dilateerode with alpha as masking what to not change. Then add some background if U need. Dilate/Erode

Awesome thanks for that… the color vibrance thing works perfectly :slight_smile: