About AVIF and PNG
AVIF is the newest of the four, built on the AV1 codec. It usually produces the smallest files, handles transparency and wide color, and is supported by all modern browsers — encoding just takes longer.
PNG is lossless with full alpha support. Screenshots, UI assets, and anything with sharp edges or text stay pixel-perfect — the tradeoff is large files for photographs.
Converting AVIF to PNG is lossless — pixels come through exactly as they were. Files are converted on the fly and never stored.