Which compression mode will JPEG XL use?+
Lossless pixels, lossy pixels and reversible recompression of an eligible JPEG bitstream are separate modes. Exact JPEG reconstruction requires its reconstruction data, not just matching rendered pixels. Quality defaults to 80; adjust it in Advanced options. File size depends on the image and encoder.
Are bit depth and colour values guaranteed to match?+
Pixel conversion only. Original EXIF, GPS, XMP and ICC profiles are not copied; processing uses 8-bit display pixels.
Will metadata and colour profiles be retained?+
Pixel conversion only. Original EXIF, GPS, XMP and ICC profiles are not copied; processing uses 8-bit display pixels.