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May 2001
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2001.05.13 14:54 "Re: TIFF/CCITT Group 4 Compression uses LZW??", by Frank Warmerdam
"Rishel,Wes" wrote: > > I have a file which, according to the GNU utility tiffinfo is a Group 4 TIFF > (see below). > > When I run the utility thumbnail against the image I get the message > "thumb.tif: LZW compression no longer supported due to Unisys patent > enforcement." > > I am a bit surprised find that Group 4 compression would use LZW or be > reliant on any patented algorithm. Does anyone know if that is, indeed the > case? Or is it more likely that the error message is incorrect, perhaps > triggered by the unknown field identified by tiffinfo? Wes, I looked at thumbnail and I see it defaults to using LZW compression for the generated thumbnails. This is what triggers the error report, not any LZWishness of G4. I have corrected this in CVS, but if you want to use thumbnail you will need to change COMPRESSION_LZW to something else like COMPRESSION_PACKBITS and recompile the program. Thanks for the report. Best regards, ---------------------------------------+-------------------------------------- I set the clouds in motion - turn up | Frank Warmerdam, warmerdam@pobox.com light and sound - activate the windows | http://pobox.com/~warmerdam and watch the world go round - Rush | Geospatial Programmer for Rent