Last modified: 2014-02-12 23:35:56 UTC
The "-fuzz 5%" option, used for scaling animated GIFs to reduce their file size since r71354, causes some animations to be rather badly corrupted. An illustrative example is [[File:Pluto_animiert.gif]], which looks fine at full size but is full of messy artifacts when downscaled. Rescaling the image on my computer using the exact same "convert" command as currently used by MediaWiki, but without the "-fuzz 5%" switch, eliminates the artifacts. It does also increase the file size by about 20%, but this is to be expected: the *reason* the current thumbnail looks bad is because it's missing large chunks of image data. I'd suggest that the -fuzz switch should either be removed entirely, or at least that the fuzz threshold should be lowered significantly, e.g. to 1% or 2% at most. (2% seems to be the highest value giving no visible artifacts for _this_ particular image; of course, some other animations may be even more sensitive.) This will increase animated GIF thumbnail sizes somewhat, at least for some images, but the "-layers optimizeTransparency" switch should still prevent the truly huge thumbnail sizes that bug 11822 was about.
