On 11/5/22, Clément Bœsch <u...@pkh.me> wrote: > Hi, > > This patchset essentially fixes a few core problems in these filters and > switches to a perceptual model. > > I've generated a report for each key commit on this (temporary) page: > http://big.pkh.me/pal/ (warning: heavy page, ~500M; I did try to add some > lazy > loading of the images but I'm not sure it's actually working as expected). > > It is easy for me to add specific samples and re-run the whole thing, so > feel > free to suggest one. > > A summary on a few important observed differences can be found on the page, > but > I'm duplicating it here for the record: > > - Current: current state on master > - Paletteuse Perceptual > + same palette but better selection: instead of rgb triplet distance, > it uses a > colorspace designed for uniform perceptual color differences (OkLab) > + overall impact not that visible immediately, but it will make sure > the > palette is used the best way possible, meaning improvements to > palettegen > will be honored > + observations (with no dither): > * file02 (rooftops) in max_colors=8 or 16: sky pattern is more > stable > * file06 (parrot) in max_colors=8: better color for the parrot > beak > * overall seems to favor slightly brighter colors in the currently > offered palette > - Palettegen Linear Average > + sRGB colors are gamma encoded, averaging them naively is incorrect, > we > need to do that in linear space > + observations (with no dither): > * file00 (colorful drawing) in max_colors=8: contrast and color > skin > look better > * file07 (abstract flower) in max_color=128 or 256: this picture > composed of 1M different colors in the source is now more > balanced > (better spreading of the colors) > - Palettegen Perceptual > + similar to the paletteuse perceptual, we use OkLab for the color > distance > + observations (with no dither): > * file07 (abstract flower): in max_colors=128 or 256 we can see > the > picture offering a much finer grain. > - Palettegen Variance per axis > + When deciding on spliting a box along an axis, instead of picking > the > longest one, we pick the one with the most color variance > + Not that much impact > > Overall, the most brutal change is probably in file07 between current and > last, > 256 colors no dither in particular. > > Finally, I do believe a lot of other color filters could at least benefit > from > fixing their gamma handling (I know I'm guilty of this in various other > filters).
gamma handling depends not on pixel format but on metadata present in frame. > > Regards, > > -- > Clément B. > > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe". > _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".