The DCMJP2K Module - a Short Overview

[Marco Eichelberg]

This discussion forum is about the DCMJP2K module, an extension of the OFFIS DICOM Toolkit (DCMTK) that is not part of the freeware distribution, but can be licensed separately. The module adds support for compressing and decompressing DICOM images using the two JPEG 2000 transfer syntaxes based on JPEG 2000 Part 1 (ISO/IEC 5444-1:2000):

• JPEG 2000 Lossless Only Transfer Syntax (1.2.840.10008.1.2.4.90)
• JPEG 2000 Transfer Syntax (1.2.840.10008.1.2.4.91)

It should be noted that support for sending and receiving such objects over a network connection is already contained in the free toolkit and, therefore, is not a part of the DCMJP2K module. The DCMJP2K module resembles in its structure the DCMJPEG module in the free toolkit, i.e. it consists of the following components:

• A library that implements the compression and decompression codec. The codecs are derived from class DcmCodec in the free toolkit and can be registered at runtime like any other compression/decompression codec (e.g. like the JPEG or RLE codecs in the free toolkit).
• Two command line applications that serve as example tools and make available the compression and decompression functions, respectively, on the command line, similar to the dcmcjpeg and dcmdjpeg tools in the free toolkit. All internal options of the JPEG 2000 codec are available through command line options.

The implementation of the JPEG 2000 compression/decompression algorithm is based on the well-known JasPer toolkit, with various bug fixes (for images with a bit depth of more than 8 bits/sample) and a few patches that improve the performance of the codecs.

A free evaluation version is available, but subject to an evaluation license agreement. The evaluation version only contains the binary command line tools, which are limited through a license file to only work for three months time. Licensees of the full license receive the full source code of the toolkit, permitting them to enhance or fix the toolkit by themselves, if desired.

The DCMJP2K toolkit has been successfully tested against the JPEG 2000 reference implementation of the DICOM committee (based on Dr. David Clunie's dicom3tools) and against the JPEG 2000 implementations from Aware, DR Systems, Medical Connections and the free dcm4che toolkit.