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Adobe Deflate Compression

The TIFF (Tagged Image File Format) library supports various types of compression. The compression type is stored as a tag (an integer value) in the file.

Originally, the TIFF library had support for LZW (Limpel-Zev Welch) compression. Unfortunately, there was a patent on this compression scheme. The TIFF added gzip compression (which is patent free) to avoid legal issues. The developers of the TIFF library created a new tag value (the tag COMPRESSION_DEFLATE had a value of 32946) to indicate that gzip compression was used.

Adobe decided that they didn't like the COMPRESSION_DEFLATE value and decided to create a new compression style called ADOBE_DEFLATE (which had an integer value of 8 instead). This compression method uses exactly the same functions for compression/decompression as the COMPRESSION_DEFLATE tag, but has a different tag value.

In their wisdom, some versions of software from Adobe do not support the ADOBE_DEFLATE tag.