LZW decompression in Panda

    Several people have tried to convince me that decompression of LZW compressed information is not covered by the various Unisys patents on the LZW compression algorithm. This decompression would be useful for the reading in of existing PDF documents, as well as the inclusion of GIF images within a PDF document.

    Having now done some research on the topic, it would appear that this is incorrect. An example is xpdf which is forced to convert the LZW compressed streams into something else before they can be used. My reading of the LZW license is also that this is the case.

    Therefore, Panda will ont be supporting the inclusion of GIF images, or the the modification of PDF documents containing LZW compressed streams in the forseeable future. When the modification of such documents is supported, it will be implemented in a similar manner to that used in xpdf.

posted at: 04:00 | path: /panda/panda-documentation | permanent link to this entry