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December 1999
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1999.12.07 17:17 "Re Deflate - Patch for libtiff", by Michael L Welles
The patch has been applied to the CVS repository. Thanks, Ivo! I don't have access at this moment to either PhotoShop or ImageReady so I haven't been able to create any ZIP compressed images to test. If anyone's interested in testing more thoroughly (or at all), instructions for for anonymous CVS access are at http://www.libtiff.org/. Ivo Penzar writes: > Today I wrote: > > Redefine the COMPRESSION_DEFLATE from 32946 to 8 and use the tiffcp tool > (for example) to > > save the TIFF image with ZIP/Deflate compression, and both Photoshop and > > ImageReady will quietly open this TIFF image just like any other regular > > TIFF file. > > > There is a better way, a patch for the libtiff to support BOTH the old > value=32946 and the new value=8: > > 1) In the file tiff.h find the following line (beginning of TIFF Tag > Definitions): > > #define COMPRESSION_DEFLATE 32946 /* Deflate compression */ > > and add a new one right after this: > > #define COMPRESSION_ADOBE_DEFLATE 8 /* Deflate compression, as > recognized by Adobe */ > > > 2) In the file tif_codec.c find the following line (definition of TIFFCodec > _TIFFBuiltinCODECS[] variable) > > { "Deflate", COMPRESSION_DEFLATE, TIFFInitZIP }, > > and add a new one right after this: > > { "AdobeDeflate", COMPRESSION_ADOBE_DEFLATE, TIFFInitZIP }, > > > 3) In the file tif_zip.c find the following line (implementation of > TIFFInitZIP() method) > > assert(scheme == COMPRESSION_DEFLATE); > > and replace it with the following one: > > assert((scheme == COMPRESSION_DEFLATE) || (scheme == > COMPRESSION_ADOBE_DEFLATE)); > > That's it! > > > > Otherwise, use ACDC (for example) to convert the TIFF image to > > the ZIP/Deflate compression, open that file by your favorite HEX editor > > (mine is A.X.E.), and find the raw byte sequence of 0x010300030000000180b2 > > (MM), or 0x0301030001000000b280 (II) and change it to > 0x01030003000000010008 > > or 0x03010300010000000800 respectively; the image is ready again to be > > quietly opened by Photoshop 5.5 or ImageReady 2.0. > > Explanation: find and replace tag 259, value=32946 to value=8. I opted to > search for all 10 bytes (the whole signature of compression tag) to avoid > possible other instances of two-bytes sequence 0x80b2 (MM), i.e., 0xb208 > (II). > > > Ivo > > ------------------------------------------------------ M. L. Welles mike@onShore.com -------------------------------------------------------