I need to mess around with JPEG XL, I think. Look at what you can pull off in <200 bytes with the format: https://jpegxl.info/art/big_gallery.html (it's hardly Rembrandt, but still..)
jpegxl.infoJXL Art gallery – JPEG XLJXL art gallery with links to source code. Procedural images as tiny JPEG XL files (SDR).