Grok (JPEG 2000)

Grok is a computer software library to encode and decode images in the JPEG 2000 format. It is designed for stability, high performance, and low memory usage. Grok is free and open-source software released under the GNU Affero General Public License (AGPL) version 3.

Grok

Developer(s)	Aaron Boxer
Initial release	January 1, 2016; 9 years ago (2016-01-01)
Stable release	15.0.0 / May 10, 2025; 2 days ago (2025-05-10)[1]
Repository	github.com/GrokImageCompression/grok
Written in	C++
Operating system	macOS, Windows, POSIX
Platform	x86-64, AArch64
Predecessor	libopenjp2
Available in	English
Type	Graphics software
License	AGPL v3
Website	github.com/GrokImageCompression/grok

Grok was forked from OpenJPEG's libopenjp2 in April 2016 by Aaron Boxer under a copyleft license.One of his goals was to close the performance gap with the more efficient but proprietary Kakadu. Grok fully implements the ISO/IEC 15444-1 technical standard. As of 2024, the newer, complexity-reduced High-Throughput JPEG 2000 standard (HTJ2K, ISO/IEC 15444-15, ITU-T T.814) has been implemented, with both encoding and decoding support available.

Features

• support for High-Throughput JPEG 2000 (HTJ2K) encode/decode
• full encode/decode support for ICC colour profiles
• full encode/decode support for XML, IPTC, XMP and EXIF meta-data
• full encode/decode support for monochrome, sRGB, palette, YCC, extended YCC, CIELab and CMYK colour spaces
• full encode/decode support for JPEG, PNG, BMP, TIFF, RAW, PNM and PAM image formats
• full encode/decode support for 1–16 bit precision images
• supported platforms: Linux x86-64, Linux AArch64, Windows, macOS and WebAssembly

Integration

Grok has been integrated into a number of other open source projects, including:

• Cantaloupe image server
• IIPSrv image server
• Horos medical image viewer