1997.01.14 15:51 "Re: Problem with CCITT G4 and long scanlines", by Frank D. Cringle

I am using v3.4beta35 on WinNT and have run into some problems with Group 4 compression when the scanline width exceeds 65536 pixels (16 bits ?).

Decompression, for G3 and G4, is handled by tif_fax3.[h,c]. There is a built in assumption that uint16 is sufficient to hold a run-length. So decompression certainly won't work with >65535 pixel lines. If you change most occurrences of uint16 to uint32 in those 2 files it might work. Most? Well, all except the one in typedef struct TIFFFaxTabEnt in tif_fax3.h, I guess. This is from a very brief eyeballing of the code. I haven't tried it and I don't have time to get involved. Sorry.

--
Frank Cringle, fdc@cliwe.ping.de
voice: (+49 2304) 467101; fax: 943357