3.6.0

This release writes metadata into AVIFs and JPEG XLs, makes PNGs of graphics up to 30% smaller and lossy WebP encoding about four times faster by default. There are no breaking API changes.

await image.encodeAVIF({ metadata: { author: 'me', description: 'a cat' } });
await image.encodeJXL({ metadata: { software: '' } });   // without the software tag
await image.encodeWebP({ quality: 75 });                 // effort 2 now, about 250 ms for 1920x1080
await image.encodeWebP({ quality: 75, effort: 4 });      // like cwebp's default, as before

New

Metadata in AVIF and JPEG XL

encodeAVIF() and encodeJXL() take metadata like the other encoders: author, description, copyright, creation time and software (by default ImageScript and its version) as Exif.

• AVIF: an Exif item that describes the image, like libavif writes it
• JPEG XL: the codestream goes into the container, with an Exif box. The codestream is still byte for byte what cjxl -e 1 writes. As the creation time is always written, JPEG XLs are now always in the container (about 250 bytes more), like JPEGs and WebPs always have Exif

Improvements

• PNG (and APNG): rows are left unfiltered when that compresses better than the paeth filter, as it often does for graphics and screenshots: their files are up to 30% smaller, and encoded faster. Photos are encoded as before, about 8% slower
• Lossy WebP defaults to effort: 2 instead of 4: about a quarter of the time (about 250 ms instead of 900 ms for a 1920×1080 photo) for files about 5% larger, at a slightly lower quality (about 0.5 dB PSNR). effort: 4 still encodes byte for byte like cwebp's default
• AVIF encoding also splits blocks into halves where that pays off: files about 2% smaller at the default effort, about 20% slower. effort: 2 also chooses smaller transforms within blocks: about 1% smaller (up to 4% for graphics)

Performance

• Lossy WebP with effort 3 to 6 is about 25% faster, with byte for byte the same files