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December 2003
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2004.01.02 06:52 "Re: Non Color - Compression in 3.6.X", by Carl J Collin
I don't know what to tell you. This is all the information I have... Tiffinfo reported this to me on my original "greyscale" file. TIFF Directory at offset 0xd4 Subfile Type: (0 = 0x0) Image Width: 1600 Image Length: 2000 Resolution: 200, 200 pixels/inch Bits/Sample: 8 Compression Scheme: None Photometric Interpretation: min-is-black FillOrder: msb-to-lsb Orientation: row 0 top, col 0 lhs Samples/Pixel: 1 Rows/Strip: 19 Planar Configuration: single image plane Software: Oi/GFS, writer v00.06.02 I then tried to perform this command to compress: tiffcp -c jpeg ds1encounter1.tif compressed.tif and got this error: TIFFReadDirectory: Warning, ds1encounter1.tif: unknown field with tag 32934 (0x80a6) encountered. ds1encounter1.tif: Warning, incorrect count for field "Tag 32934" (0, expecting 1); tag ignored. JPEGSetupEncode: RowsPerStrip must be multiple of 16 for JPEG. So I performed this command: tiffcp -r 16 -c jpeg ds1encounter1.tif compressed.tif and got this error: JPEGLib: Bogus input colorspace. So I performed this command: tiffcp -r 16 -c jpeg:r ds1encounter1.tif compressed.tif and got no error, but when I tried to view the image using "display" which is from ImageMagick I get this error: display: Sorry, can not handle RGB image with Color channels=1. (compressed.tif) So I thought maybe ImageMagick is just f'd up, so I tried to reverse the compression ala "tiffcp -c none compressed.tif uncompressed.tif" and while the file size has expanded, the file is still reporting the same error in display (ImageMagick) display: Sorry, can not handle RGB image with Color channels=1. (compressed.tif) Now the really interesting point again is that this works fine for if my original file has this for its tiffinfo: TIFF Directory at offset 0x8 Subfile Type: (0 = 0x0) Image Width: 849 Image Length: 933 Resolution: 72, 72 pixels/inch Bits/Sample: 8 Compression Scheme: LZW Photometric Interpretation: RGB color Samples/Pixel: 3 Rows/Strip: 3 Planar Configuration: single image plane Photoshop Data: <present>, 2968 bytes Predictor: horizontal differencing 2 (0x2) It seems for all files that have a Photometric Interpretation of RGB color the compression schema works fine. The other "really interesting thing" is that those broken compressed/uncompressed files above that don't work in the ImageMagick program or in the Wang viewer work FINE in Irfanview. So what the hell is going on? Any ideas.... I can send files to anybody whom can help out, I'm just trying to figure out why the compression and decompression leaves the files in a state that seems can only be read by some programs. Thanks!