2021.05.02 00:36 "[Tiff] SIMD optimizations", by Larry Bank
Thread
2021.05.04 18:07 "Re: [Tiff] SIMD optimizations", by Toby Thain
I brought up this issue years ago. The libtiff G4 encoder is needlessly inefficient in both its encoding of the output bits and its searching the current and reference lines for runs of bits. There isn't just a tweak to fix it, the encoder needs to be tossed out and replaced. A faster encoder will use a bit more memory, but at this point I don't think anyone will mind using an additional 8 bytes per pixel width (current + reference line runs as uint32_t). I've been recently reminded on this mailing list that my time is better spent optimizing more important libraries like libpng. Are there any good reasons to change my mind? I still think that libtiff G4 encoding is used widely in scanned document generation (embedded in scanners and on PCs/mobile), so it should be improved.
I use G4 for every bilevel scanned document I ship, so yes. However, the existing encoder is still pretty darn fast :)
--Toby