In addition to size (as BrowserUk already noted), you will also need to consider color -- color mapping, color pallet, and color index. Most importantly; the index must be the same for all images used within your animation. else you will not be able to attain a transparent background (if you intend one) and there will be pixelization(sp) which it appears you are describing. Easiest way to discover this info, is probably to open the three images in your image management software (gimp, photoshop, etc...), and look for these factors (compare them). Perhaps there's an "image info(rmation)" in the programs menu? I know the gimp has it, and I can't imagine the others wouldn't. If their not, you should be able to reduce the colors to that of the image with the least colors. There's usually "import" the other images into the one with the lowest color value. Which will "unify" the pallet for all three.

--Chris

Yes. What say about me, is true.