For Medical Imaging Solutions
Wavelet transform-based image compression algorithms are recognized as a superior method to compress, archive, and electronically disseminate medical imagery. This class of algorithm is now available to a wider medical system user base with the approval of JPEG2000 as an accepted image compression option by the DICOM Working Group 4 (compression group).
JPEG2000:
Accepted as a DICOM Compression Option
 JPEG2000 support was added to the DICOM standard in November 2001 with the publication of Digital Imaging and Communications in Medicine (DICOM) Supplement 61: JPEG2000 Transfer Syntaxes. As described in Supplement 61, WG 4's motivation was based on the fact that "…there are both real and perceived limitations" with traditional JPEG. "…WG 4 began to investigate alternatives, particularly those based on wavelet transformation, multi-resolution analysis and more sophisticated entropy coders than Huffman coding." The adoption of JPEG2000 as an ISO standard provided DICOM with a timely solution. Both the JPEG2000 lossless compression and lossy compression algorithms have been accepted for use.
Aware and Medical Image Compression
Aware, Inc. was the first commercial organization in the world to provide a wavelet based image compression algorithm to original equipment manufacturers for use in medical systems. Our active development and commercialization efforts have helped promote the adoption of wavelet based compression by the medical industry. Today some form of wavelet algorithm is used by all of the major medical imaging systems providers.
The adoption of JPEG2000 as a standard by the ISO and the inclusion of JPEG2000 as part of DICOM is a validation of the newer technology and is the logical result of the desire for a more advanced yet standardized method for the compression and transmission of medical images.
Aware's JPEG2000 Codec for Medical Applications
The Aware JPEG2000 library and software development kit are fully optimized for medical images. The libraries, example programs, and viewing tools are developed and maintained by the Aware compression group. Our focus is a fully supported, fully optimized, and fully featured implementation of the standard with enhancements and add-on capabilities that make it more useful for medical applications. Benefits and Features include the following:
Superior Image Quality
The JPEG2000 lossless compression option enables the archival of compressed lossless images, eliminating any concerns of the impact of compression on image quality for diagnostic purposes. Achievable compression ratios in lossless mode are 2:1 to 3:1. The scalability of JPEG2000 provides a significant benefit over traditional lossless JPEG, however.
Multiple Lossy Versions from the Single
Lossless or Lossy Compressed Image
The archived image can be compressed and saved in lossless or near lossless form. Multiple smaller blocks of data can be extracted from these very high quality compressed files and progressively decoded and viewed from networked clients.
Progressive Display
The Aware JPEG2000 library provides full support for the multi-layered file format and for the progressive decode/view that can be achieved with the format. An image can be displayed almost immediately after only a small portion of the file has been received. As more data is received, the resolution or quality of the image will be automatically refined. For bandwidth constrained applications, only the additional quality or resolution layers need be transmitted.
The above series shows the "encode/decode by quality"
layers capability of JPEG2000
Region of Interest Encoding
Region of Interest (ROI) encoding allows important image features to be compressed at a higher quality than the background, trimming file size without sacrificing important details. When combined with progressive display, ROI encoding also allows the foreground to be transmitted and displayed first, followed by the image background.
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Original Image |
Decoded image using rectangular ROI centered on screw |
Medical Library Supplement
The Aware JPEG2000 Developer's Toolkit includes a supplemental library that is designed to facilitate the usage of JPEG2000 with the DICOM standard.The Medical I/O Supplement supports the following conversions:
- DICOM with embedded Raw image to DICOM with embedded JPEG2000
- DICOM with embedded JPEG2000 to DICOM with embedded RAW
- Extraction of embedded RAW to separate JPEG2000 file
- Extraction of embedded JPEG2000 to separate RAW file
- Full DICOM file parsing and access to the most commonly used tags
- Update of the DICOM file to reflect changes to the image data
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Aware JPEG2000 DICOM File Support Options |
Easy Viewing
The Aware JPEG2000 for Medical Development Toolkit includes example programs and source code that show how to call the Aware libraries to compress/decompress and display the images. Full support for multi-channel images at up to 16 bits/channel, and support for signed and unsigned images is provided. 
Pocket PC Plug-in
Aware's PocketPC plug-in allows wireless transmission and display of images to a Microsoft PocketPC device. The plug-in takes full advantage of JPEG2000's higher compression to cut image transmission time, conserve wireless bandwidth and store more images in the handheld's limited memory. The plug-in also performs progressive display and supports interactive pan and zoom to display high resolution images on a small screen.
Technical Features
- A fully standard-compliant implementation of the JPEG2000 standard - over 70 functions in the API
- Same API supports MS Windows, Solaris, Linux, IRIX, Windows CE
- Highly Optimized for speed, particularly for 10-16 bit medical imagery
- Very accurate rate control including bit rate per layer capability
- File I/O capability enables JPEG2000 to/from BMP, TIF, RAW, PGM, and JPEG
- Medical Supplement Library supports JPEG2000 with DICOM files
For more information about Aware's JPEG2000 Codec for Medical Applications, contact us today.
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