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May 2001
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2001.05.12 23:08 "TIFF/CCITT Group 4 Compression uses LZW??", by Wes Rishel
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? Thanks. ------------------------- output from tiffinfo follows C:\Program Files\gnu\libtiff\bin>tiffinfo SampleTiff.tif SampleTiff.tif: Warning, unknown field with tag 32934 (0x80a6) ignored. TIFF Directory at offset 0xd4 Subfile Type: (0 = 0x0) Image Width: 1132 Image Length: 1686 Resolution: 200, 200 pixels/inch Bits/Sample: 1 Compression Scheme: CCITT Group 4 Photometric Interpretation: min-is-white FillOrder: msb-to-lsb Software: "Oi/GFS, writer v00.06.02" Orientation: row 0 top, col 0 lhs Samples/Pixel: 1 Rows/Strip: 223 Planar Configuration: single image plane Group 4 Options: (0 = 0x0)