XV also supports the GIF 'aspect ratio' extension that was discussed on comp.graphics. Here's the description: ---------------------------------------------------------------------------- There was quite a discussion in comp.graphics a few weeks ago, with a lot of people complaining about GIF images coming with many different aspect ratios, but no indication what the initial aspect ratio was. Several suggestions were made, the best of which was Chris Schoeneman (i think) suggesting the following extension block be added to specify the aspect ratio: # 7 6 5 4 3 2 1 0 Byte # # +---------------+ # |0 0 1 0 0 0 0 1| 1 '!' - GIF extension block introducer # +---------------+ # |0 1 0 1 0 0 1 0| 2 'R' - For 'aspect Ratio' # +---------------+ # |0 0 0 0 0 0 1 0| 3 2 - Two bytes in block # +---------------+ # | pixel width | 4 - First part of ratio (numerator) # +---------------+ # | pixel height | 5 - Second part of ratio (denominator) # +---------------+ # |0 0 0 0 0 0 0 0| 6 0 - extension block end code # +---------------+ # #Let byte four equal 'x' and byte five equal 'y' Then x:y is the _pixel_ #aspect ratio. 'x' and 'y' should be relatively prime (ie they should #have no common divisor except one), but they don't have to be. Jef Paskanzer [of PBMPLUS fame] modified his gif decoder to recognize this. I also modified my own, not that I count :-) Jef and I cross-checked ours and these diffs are compatible with both. This code, by the way, isn't terrible robust, and will only skip extensions found BEFORE the image separator, but it is a lot better than nothing. Since then, there has been a seemingly official announcement about a GIF89a standard from CompuServe, and the possibility of both GIF's becoming outlawed because of the Unisys LZW patent, etc. etc. etc. oh, well... life goes on. anyway... I hope this is of some help. you are welcome to post these patches to wherever is appropriate (i didnt do a patch on patchlevel.h, b.t.w.), or incorporate them into your new program, or whatever. I relinquish all claims, etc. etc. -steve -------------------------------------------------------+"Come, Watson, come!" Steve Swales (716) 275-0265,-3857,-5101| he cried. "The game is steve@bat.lle.rochester.edu (128.151.32.111)| afoot. Not a word! {decvax,harvard,ames,rutgers}!rochester!ur-laser!steve| Into your clothes and University of Rochester 250 East River Road| come!" S.H. Laboratory for Laser Energetics Rochester, NY 14623| 'The Abbey Grange'