Image compatibility fixes
- Kobo: WebP images, including covers, are now converted to lossless PNG for kepub and kepub3, even when image optimization is disabled. Transparency is preserved unless removal is requested; configured cover resizing still applies.
- Transparency: Transparent TIFF and WebP images now flatten correctly onto white for Kindle output or when remove_transparency is enabled, avoiding dark backgrounds during JPEG conversion. For EPUB/KEPUB output, flattened images use PNG to avoid JPEG artifacts.
- Existing behavior is preserved for Kobo-supported formats and ordinary EPUB output.
Documentation and maintenance
- Updated format guides and configuration comments to explain image conversion, transparency, and cover handling.
Full Changelog: v1.9.0...v1.9.1