CompuServe Thread

#Color Pallette Problem

3 messages in this thread
#38317From: Ken Loss-CutlerMar 24, 1993 11:06 AM
We're having a persistent problem here and would like some help and advise. When we view an image in 3DS it looks fine. But when we put the image on the background and render it, the colors have changed. There does not seem to be a method to why the colors are changing. This does not happen with every image, but only from time to time. We are also having similar problems when rotoscoping an image. It doesn't seem to be an animation problem, but a more general rendering problem, because when we render in the 3D Editor the problem is there, too. We first noticed this problem when rotoscoping a fli file into a 3DS animation and thought it might be a problem involving translating pallettes, but we have now experienced the problem also when mapping a 512×486 or 320×200 image into a 756×486 environment. Even if we render in the same aspect ratio as the image was originally rendered in, though, we still see the color problems. We don't know for sure that this would happen with an image which was ORIGINALLY rendered at 756×486 (indeed we have not had a problem YET in this) but cannot tell from our experience if resolution is the critical factor or not. It is, for sure, confusing and keeping us from doing a couple of projects, so we would appreciate any feedback and ideas you might be able to provide. [A One other item: It doesn't happen consistently on every frame, but seems to occur all the time in some sequences but inconsistently in others. Hmmmm…. Regards- Ken and Brian
#38342From: Yost GroupMar 24, 1993 3:42 PM
When 3DS scales an image either up or down, it uses a method of bilinear interpolation of RGB values to make the image look as smooth as possible. The interpolating process creates scores of new colors, and this is why you're getting slight color changes when scaling. When you don't scale, however, the only things that can cause color shifts (in 24-bit, of course) would be using either fog or depth cueing. If you can send me an example of what you're talking about, I can tell you specifically what's going on. – G
#38355From: Ken Loss-CutlerMar 24, 1993 5:03 PM
Gary: We're not talking "slight color changes here", old friend <g>. We are going to send you an example so you can see it. Thanks for your help. Regards- Ken and Brian