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May 2008
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2008.05.26 19:32 "Re: beta2 release - predictors", by Edward Lam
Hi, Just I've been doing some testing with tiff 4.0 beta 2, and with predictors in particular. I've noticed that the following cases result in a larger compressed sizes when a predictor is used: - 8/16-bit PixarLog (PREDICTOR_HORIZONTAL) - 32-bit floating point LZW (PREDICTOR_FLOATINGPOINT) - 32-bit floating point AdobeDeflate/Deflate (PREDICTOR_FLOATINGPOINT) For PixarLog, I'm not sure it makes sense to create them out of 8 or 16-bit integer values in the first place so I'm not particularly surprised. It does result in smaller compressed sizes when 32-bit floating point is used. However, for the 32-bit floating point cases, I would expect that PREDICTOR_FLOATINGPOINT would produce better compressed file sizes. Mind you, I'm perhaps basing this too much on my single image test case, but I figure I'll throw it out there. Maybe someone will tell me that PREDICTOR_FLOATINGPOINT is not ready yet in libtiff. :) Thanks, -Edward Frank Warmerdam wrote: > Folks, > > There are no earth shattering changes, but I have prepared a libtiff 4.0.0 > beta2. Mostly this is to roll in some changes based on an old coverity > scan of libtiff, and to produce a new tarball I can pass off to coverity > for analysis. > > Coverity produces a static code analysis tool that can identify bugs not > easily discovered by code inspection, lint style tools, compiler > warnings or > runtime analysis with tools like valgrind. They kind provide free support > for a variety of projects including libtiff. I, umm, failed to followup > on their previous report some 12 months ago, but talking to their open > source > project support fellow at PGCon this week got me off my duff and looking > into > stuff. It's pretty sweet, and I'd like to see it become part of the > libtiff release development and release process over time. > > If any of the other libtiff core developers would like access to the > Coverity > reports let me know. > > Anyways, beta2 is available at: > > http://download.osgeo.org/libtiff/tiff-4.0.0beta2.tar.gz > http://download.osgeo.org/libtiff/tiff-4.0.0beta2.zip > > Best regards,