ISO/IEC 15444-5:2015 defines a set of lossless and lossy compression methods for coding continuous-tone, bi-level, greyscale or colour digital still images. This Recommendation | International Standard provides three independently created software reference implementations of Rec. ITU-T T.800 | ISO/IEC 15444-1, in order to assist implementers of Rec. ITU-T T.800 | ISO/IEC 15444-1 in testing and understanding its content. The packages are JASPER, JJ2000 and OPENJPEG.
The reference software packages are informative only. This Recommendation | International Standard does not define any additional part of the JPEG 2000 image coding system.
Each version of the reference software contains source code, which may be compiled to provide the following functionality:
- transcoding from selected, widely available image formats into a JPEG 2000 codestream;
- transcoding from selected, widely available image formats into the JP2 file format;
- selection of a wide range of JPEG 2000 encoding options (as documented in each reference software);
- decoding from a JPEG 2000 codestream to a range of selected widely available image formats;
- Processing of a JP2 file to extract a JPEG 2000 codestream for decoding and conversion to a range of selected widely available image formats.
- The ability to extract metadata from a JP2 file, including the contents of the Image Header box and the colour space.
- The decoding of JP2 files that use the Three-Component Matrix-Based form of the Restricted ICC method for the specification of colour space and the conversion of the decoded image data to the sRGB colour space for display, including limited upsampling of all decoded components to the same resolution.
- The decoding of JP2 files that use the Monochrome form of the Restricted ICC method for the specification of colour space and the conversion of the decoded image data to the sRGB based greyscale space as defined within the JP2 file format.
- The decoding of JP2 files that use the sYCC colour space and the conversion of the decoded image data to the sRGB colour space for display, including upsampling of all decoded components to the same resolution.
- some additional tools to help with evaluation and testing.
The reference software is intended for use as a testing and validation tool for other implementations of JPEG 2000, and to help in the understanding of Rec. ITU-T T.800 | ISO/IEC 15444-1. Although components of the reference software may find application in software intended for product development, this was not an objective of the development of this software, and prospective implementers are cautioned against making any estimations of performance or resource usage based on the reference software.