On Wed, Mar 15, 2017 at 10:52:29PM +0100, Mateusz Brzostek wrote: > Hello! > > There are 3 problems with DITHER_COPY macro in libswscale/swscale_unscaled.c: > 1) there is overflow in dithering from 12-bit to 10-bit (output value > 1023); > 2) for limit range the lower limit is not respected, for example from 10-bit > to 8-bit value 64 is converted to 15; > 3) for many iteration of downscale/upscale of the same image the 200th > iteration is significantly darker. > > The first bug is due to wrong dithers table (now it is OK only for 8-bit > destination), fix is: > - const uint8_t *dither= dithers[src_depth-9][i&7];\ > + const uint8_t *dither= dithers[src_depth-dst_depth-1][i&7];\ > > For bugs 2) and 3) it is needed formula that do not make images darker (in > attachment). So please review.
does your code maintain white and black levels ? with 4 bits white is 15, with 7 bits white is 127 for example white should stay white black should stay black in both directions [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB In fact, the RIAA has been known to suggest that students drop out of college or go to community college in order to be able to afford settlements. -- The RIAA
signature.asc
Description: Digital signature
_______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
