people usually only think about format when compressing images
they never think about indexed coloring
consider. Same pic. same size. one only uses 24 colors and is only 435 kb. the other is 1.5mb and uses 254 colors. This isn't very significant because the photo is grayscale and doesn't use many colors in the first place. However…
>>27795this does not count as "grayscale" since grayscale images use all 0-saturated shades of gray between between white and black. These images only use 2 arbitrary colors. No in between shades whatsoever. The dithering uses different ratios of "spackling" of the two colors to create the illusion of a gradient when zoomed out.
Floyd-Steinberg dithering was used the most in the 90s, but was invented all the way back in 1976. That's 46 years ago!
>>27800thanks for sharing!
>>27802my vision is good. i got my eyes checked when I got my license renewed. I appreciate your opinion.
>>27831see
>>27791>>27851>why the hell do we need to cut the size so muchso we don't have to wait an hour for your image to load
Popular image formats usually have very good compression. Compare this to scanned documents, where PDF has proliferated, despite DJVU having objectively better compression and faster rendering by a wide margin.
Look at this random book from archive.org (
https://archive.org/details/inferno00dant_2/). The DJVU looks much clearer than the native PDF with more than double the size and the PDF containing JPEGs has marginally more detailed illustrations at four times the size. The text of the DJVU looks crisper than that of both PDFs.
Most books on archive.org don't have DJVUs anymore, so I usually losslessly convert a directory of JPEG2K files to a PDF and transcode it to DJVU with this script:
#!/bin/sh
t=`mktemp`; d=`mktemp -d`
for i in $1/*.[Jj][Pp]2; do
jpeg2ktopam $1|pamtotiff >$t &&
tiff2pdf -o "$d/`basename $i|cut -d. -f 1`.pdf" $t
done
pdfunite $d/* $t &&
djvu2pdf $t > $2
rm $t; rm -r $d
This requires netpbm and pdf2djvu.
>>27861>aestheticsI think what would help with aesthetics more than anything is an AI step when compressing. Reducing colors often leads to objects blending into each other or the background. Fixing this by hand takes a small eternity, so AI finding the borders of objects to find a setting with a given reduction of colors with little blending would be good.
And AI should also do a bit of phony coloring (not taking the nearest color from the reduced set) if that helps a lot against blending.
Oh and also, the AI should distinguish between things like machines and buildings on the one hand and organic structures on the other and apply something like the Bayer dither to the former and a less orderly dither to the latter.
>>27787That's because dithering looks like shit and we have better displays now than we did in the 90s when color quantization was still a passable compression solution. But now we have jpeg.
Use jpeg instead and an encoder like mozjpeg for your Lenin portraits
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