@Sunweb
A new day, some more tests.
1. I can not visually see any difference between your PNG .png and your AVIF GIMP 2-10 lossless.avif Using Sample points on your area of interest, there are tiny changes in blue and red but literally just 1 point example 50 -> 51.
2. The whole point is a smaller file size and setting lossless might be unjustified. see:
https://www.finally.agency/blog/what-is-...age-format I do not know how reliable that is, it is about 18 months old and it claims avif lossless implementation is not very good.
for file size and I see no visible change in colours unless you are very picky.
3. Using ImageMagick (IM), You need a IM7, current is 7.1 some info here:
https://avif.io/blog/tutorials/imagemagick/
Depending on settings I can get a 100% quality with a file size = 939 kb down to 80 quality = 28.7 kb Zoom in to pixel size, you can see differences, the avif has implemented some smoothing, but that is the trade-off for file size and I see no visible change in colours unless you are very picky.
Code:
magick -quality 80 -define heic:speed=2 PNG.png png2.avif
Attached as an IM example. Unzip it.
Paint.Net files not compatible with browser ? I do not use, but check you have the correct files installed.
https://avif.io/blog/tutorials/paintnet/
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Edit: avif is not a format I use, but it is basically a video format. ffmpeg is another utility. A little like ImageMagick (IM), if you have an up-to-date version, it will convert png -> avif. It might be closer to that Gimp 2.99 plugin for YUV colorspace, I have not got that far yet.
However, for IM7 you can get a higher bit depth which might be closer to your png and a much smaller filesize.
Code:
magick PNG.png -quality 80 -depth 12 80-12.avif
That opens in Gimp as 16 bit file. Open As Layers the PNG.png and compare.
attached 80-12.avif zipped, unzip it.
One thing I noticed in the png, some artifacts Was it originally a jpeg ?
