On Tue, Aug 28, 2012 at 12:56:47PM +0200, Vincent Lefevre wrote: > Before wondering whether PNG files should have an additional > compression level, is there any reason why a better PNG compression > isn't used in the first place? For instance, "optipng -o9" tries > various parameters and keeps the best one.
optipng can improve only earlier stages of PNG format (ARGB->paletted, pixel filters), its deflate implementation is pretty bad. You'd want to use it together with advpng (package advancecomp) which attacks the deflate stage better: optipng -o4 -i0 -fix $* && advpng -z4 $* (Optimizations above -o4 affect deflate only, advpng is scared by interlaced images and files with junk after PNG data.) As per my tests, other combinations of PNG optimizers give worse results, and in some cases (PNGOUT, fortunately not in Debian) even destroy images. It might be possible to compress files even better by tossing away dubious chunks added by some editors (Adobe stuff is especially notorious), but that can be argued to be data loss of sorts. -- Copyright and patents were never about promoting culture and innovations; from the very start they were legalized bribes to give the king some income and to let businesses get rid of competition. For some history, please read https://en.wikipedia.org/wiki/Statute_of_Monopolies_1623 -- To UNSUBSCRIBE, email to debian-devel-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/20120828210353.ga9...@angband.pl
