3 ms·

Also more savings will come for JPEG XL soon. Possibly mostly focused on medium and low quality.

• kodabbb 3y ago
  will those require a bitstream change too?
  • jonsneyers 3y ago
    It is unlikely that there will be any bitstream changes in JPEG XL. There is still a lot of potential for encoder improvements within the current bitstream, both for lossy and for lossless.
  • JyrkiAlakuijala 3y ago
    No bitstream changes. In JPEG XL we have a 3-bit control field for each 8x8 square to guide which pixels participate in smoothing. The heuristics (here https://github.com/libjxl/libjxl/blob/main/lib/jxl/enc_ar_control_field.cc#L37 https://github.com/libjxl/libjxl/blob/main/lib/jxl/enc_ar_co...) for choosing that value are quite primitive and produces only two values: no smoothing and some smoothing (values 0 and 4). If we replace those heuristics with a search that tries out which of the values is closest to the original, we should get better quality, especially at the lowest bitrates where smoothing is important.