LibTiff Mailing List
TIFF and LibTiff Mailing List Archive
February 2008
Previous Thread
Next Thread
Previous by Thread
Next by Thread
Previous by Date
Next by Date
Contact
The TIFF Mailing List Homepage
This list is run by Frank Warmerdam
Archive maintained by AWare Systems
Thread
2008.02.06 11:28 "Re: Why is TIFF/zip not a default option?", by Andy Cave
Hi LZW has no remaining patent issues (they've all expired). Given that, I think it's a better general choice then flate - mainly as it's much easier for anyone to implement (a few hours (for a simple implementation) vs days for flate). Although flate does get better compression and is supported by quite a lot of s/w, it's also slower. Having said that, if your aim is for archiving, flate with the highest level compression does produce much more compressed files. Although slower, since you're archiving for posterity, do you care if it takes a little longer. Decompressing is not really any slower. I don't know if/how tifflib supports flate compression with the highest level though? So I think you could choose either, or both. Regards, Andy. ----- Original Message ----- From: "Anders Sewerin Johansen" <asjo@kb.dk> To: <tiff@lists.maptools.org> Sent: Wednesday, February 06, 2008 11:05 AM Subject: RE: [Tiff] Why is TIFF/zip not a default option? Hi, Well, the reason for my question is that as far as I have so far been able to determine the deflate option was not enabled by default, which I took to mean that the majority of the libtiff equiped systems in use weould as default not be able to handle tiff/deflate. If it turns out I was mistaken, well that's just great! The reason for the question is that several parameters are relevant for picking a format for our purposes. Some are obvious to outsiders (size of final file, CPU requirements for rendering...), while others may not be (openness of format, availability of several open source renderes, patent issues). In particular the tiff/lzw format, while suitable on most counts (stable, well-known...) is discounted due to the patent issues past, present and future of the lzw compression algorithm/implementation. The tiff/zip format would not be discounted on the patent issue as far as I know, but might be discounted with regards to cross-platform usability, if the default Linux/UNIX system configuration did not allow for reading and writing it. Can I conclude that most recent libtiff equiped systems (e.g. systems deployed or updated during the last five years) will support tiff/zip? A -------------------------------------------------------------------------------- > _______________________________________________ > Tiff mailing list: Tiff@lists.maptools.org > http://lists.maptools.org/mailman/listinfo/tiff > http://www.remotesensing.org/libtiff/