jpeg2000

jpeg2000 - JPEG 2000 Image Compression By Christine Bako

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Analog Dialogue 38-09, September (2004) 1 JPEG 2000 Image Compression By Christine Bako [christine.bako@analog.com] INTRODUCTION The JPEG (Joint Photographic Experts Group) 2000 standard, fnalized in 2001, defnes a new image-coding scheme using state-oF-the-art compression techniques based on wavelet technology. Its architecture is useFul For many diverse applications, including Internet image distribution, security systems, digital photography, and medical imaging. A lot oF conFusion exists as to what JPEG 2000 is and how it compares with other compression standards such as MPEG (Moving-Picture Experts Group) -2, MPEG-4, and the earlier JPEG. With brieF comparisons to other compression standards, this article is primarily intended to highlight some oF the oFten misunderstood and rarely mentioned potential-become-actual benefts oF JPEG 2000. Applications CCTV Security When transmitting or storing picture inFormation, compression must be employed to maintain picture resolution while making best use oF limited channel bandwidth. Compression is defned as lossless iF Full recovery oF the original is available From the channel without any loss oF inFormation; otherwise, it is lossy . Standards are required to ensure interoperability. JPEG 2000 is the only standard compression scheme that provides For both lossless and lossy compression. As such, it lends itselF to applications that require high-quality images despite limitations on storage or transmission bandwidths. An important Feature oF systems based on JPEG 2000 is the ability to extract a variety oF resolutions, components, areas oF interest, and compression ratios From a single JPEG 2000 code stream. This is not possible with any other compression standard because the image size, bit rate, and quality must be specifed on the encode side and can not be determined or changed on the decode side. ±or example, a closed-circuit TV (CCTV) security system can make use oF this Feature by sending a single JPEG 2000 code stream over a low bandwidth network. High-resolution images can be stored on a hard-disk drive (HDD), while several lower- resolution images are displayed on monitors. The operator on the receive side can decide what inFormation to extract From the single code stream sent. JPEG 2000 is frame accurate , in that every single Frame oF the input is contained in the compressed Format. MPEG systems, on the other hand, reduce the amount oF data through temporal compression (which does not encode each Frame as a complete image), so MPEG compression is not frame-accurate . ±or this reason, legal issues restrict the use oF MPEG compression in some security applications. To get around this problem, security system and equipment providers have had to develop their own compression schemes—or use the highly ineFfcient motion JPEG (M-JPEG) compression standard—in order to provide a compressed stream that contains every single feld oF the original. They can now use JPEG 2000 For new designs. Internet Image Distribution
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jpeg2000 - JPEG 2000 Image Compression By Christine Bako

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