Package: libreoffice-writer Version: 4:25.2.3-2+deb13u4 Severity: wishlist For embedded images, the export-to-PDF dialog allows us to choose only between lossless encoding and JPEG encoding (with a quality setting). However, the PDF format allows for a variety of stream formats for images. For color and gray images (i.e., not bi-level), two are particularly interesting: JPEGs with arithmetic coding and JPEG2000. Arithmetic-coded JPEGs, though not baseline in ITU T.81, are fully standardized and stable (so no risk of specification change), offer significant size gains (cf. https://en.wikipedia.org/wiki/Talk:JPEG#DAC https://en.wikipedia.org/wiki/Talk:JPEG#DAC ) and allow for substantial improvements while staying in the same image-format ecosystem. On my machine, papers 48.3 and evince 49.alpha can read PDF files with arithmetic-coded JPEGs. There is no real reason not to have them, as the corresponding patents expired. JPEG2000 is technically superior to JPEG, often providing higher quality at smaller file sizes, especially at high compression ratios. It avoids the blocky artifacts common in highly compressed JPEGs. Still, I'm sometimes surprised by the result (for the same low quality setting, some compressed images look fine, whereas others are garbage), so I do not recommend JPEG2000 as a full replacement of JPEG but rather as an addition.
