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November 1999
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1999.12.01 17:39 "Re: ZIP compression [was: libtiff 3.5.3 release.]", by Bryan H Maret
Libtiff uses a Compression value from the private range for ZIP compression - that's all that Sam could do without Adobe's official blessing. The actual TIFF 7 spec uses a Compression value from the "official" range for Deflate compression. Adobe's ImageReady uses the official value, since its developers had the benefit of the real spec. regards- -Bryan Maret (formerly Adobe's TIFF person) homefront@acm.org At 09:42 AM 12/1/99 -0500, Tom Kacvinsky wrote: >Hi, > >As you may or may not know, Adobe's Image Ready support ZIP compressed >TIFFs (reading and writing), but they use a different tag for the >compression scheme. ZIP compressed TIFFs as built by tiffcp cannot be >opened in Image Ready, and vice versa. So it lloks like Adobe is >already heading torwards adding ZIP compression to the TIFF >specification, but is using a different tag scheme. I belive that >Leonard Rosenthal (of Adobe) is on this list and could answer this >question. > >Regards, > >Tom > >> >> What is the compression tag TIFFTAG_COMPRESSION assigned to Zip? The >> file >> tiff.h says >> #define COMPRESSION_DEFLATE 32946 /* Deflate compression */ >> An associated tag is Zip quality: >> /* Note: quality level is on the ZLIB 1-9 scale. Default value is -1 */ >> #define TIFFTAG_ZIPQUALITY 65557 /* compression quality level */ >> >