OpenJPEG 2.5 Released With High Throughput JPEG 2000 Decoding (HTJ2K)
High-Throughput JPEG 2000 (HTJ2K) is for facilitating faster image decoding at the cost of slightly reduced efficiency. HTJ2K replaces the JPEG 2000 standard block coder with an alternative coder focused on vectorized performance. High-throughput JPEG 2000 Part 15 (ISO/IEC 15444-1) was only firmed up in 2019.
HTJ2K has been described as offering a "magnitude increase" in throughput for JPEG 2000 -- around 10x for moderate to higher compressed bit-rates or around 30x for lossless coding all thanks to its new HT block coder. The coding efficiency though is 5~10% lower than the original J2K-1 coder.
There has been a reference open-source implementation of HTJ2K via the OpenJPH project while now with OpenJPEG 2.5 is this additional open-source support for High-Throughput JPEG 2000.
In addition to OpenJPEG 2.5 adding HTJ2K decoding support, there is also support now for partial bitstream decoding. On the OpenJPEG encoder front, v2.5 adds support for generation of TLM markers. The OpenJPEG 2.5 release is rounded out by various bug fixes.
Windows/Linux/macOS binaries and sources for OpenJPEG 2.5.0 can be downloaded from GitHub.