I have tried your JPEG compressor. While it does make red less dull at 2x2 chroma subsampling, it does also blur red (or orange) into (white) backgrounds. IMO the sum is negative, at least with the particular image I tried.
I'm particularly interested in this because lossy WebP only supports 2x2 chroma subsampling. So any optimisation for JPEG could maybe also be applied to WebP.
I have made a topic about this once on the WebP group, which also has the image I tried with your compressor.
With chroma subsampling there's tradeoff - either bleed black into color areas or bleed color outside. If have any ideas or know research on choosing when which option is best, then I'm all ears.
I'm particularly interested in this because lossy WebP only supports 2x2 chroma subsampling. So any optimisation for JPEG could maybe also be applied to WebP.
I have made a topic about this once on the WebP group, which also has the image I tried with your compressor.
https://groups.google.com/a/webmproject.org/forum/#!topic/we...