Beats JPEG/JP2K/JXL/SQZ in PSNR
It uses CDF 9/7 wavelet transform without K-scaling + your choice of arithmetic (EBCOT-lite + BAC) or Huffman entropy coding.
Are those state of the art? What about webp and avif?
Both can`t reach 200B, they not designed for this. avif only reached 850B on lena256.png, from ~1-2kb+ avif can lead on psnr depending on vector, but for ssimulacra2 avif only wins 2-22kb range, further quantization steps become too rough avif_q91.avif->33kb, avif_q92.avif->37kb, avif_q97.avif->59kb, avif_q98.avif->71kb. webp can`t compete with avif here.