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Abstract
JPEG2000 is the new standard for the compression of images, which succeeds to JPEG. It's has a much higher algorithmic complexity. The complexity of the entropy encoder ( EBCOT) is the most significant in JPEG2000. Which alone constitutes about 70% of the overall processing time for compression of an image. This new standard has many features and characteristics (region of interest, several types of decompression). In this paper we are interested on studying the algorithm of JPEG2000 and the most complex in the JPEG2000 compression process, the EBCOT entropy encoder, and its performance are presented.
Keywords
Image compression, JPEG2000, Entropy encoder EBCOT.
1. Introduction
JPEG2000 is the new international standard for image compression [l][8]. The JPEG 2000 standard provides a set of features that are of importance to many high-end and emerging applications by taking advantage of new technologies. Some of the most important features that this standard should possess are the following [1][2][8] : Multiple resolution representation; Embedded bit-stream (progressive decoding and SNR scalability ); Region-ofinterest (ROI) coding... .
JPEG2000 has a much higher algorithmic complexity. The complexity of the entropy encoder is the most significant in JPEG2000. This alone constitutes about 70% of the overall processing time for compression of an image. The principal advantage of entropy coding: EBCOT is creating a highly scalable compressed bitstream, which can be accessed randomly. As other image compression algorithms such as SPIHT [6] and EZW [7], EBCOT uses the wavelet transform to divide the energy of the original image into subbands.
This paper is organized as follows. In section 2, we explain the encoder engine for the JPEG2000. The most intensive processing JPEG2000 (EBCOT entropy encoder) is
described, Section 3. In Section 4 shows experimental results The Obtained using JPEG2000, a comparison with SPIHT coder, and establishes the results for different characteristics of JPEG2000. Finally, section 5 contains the conclusion.
2. Principle of the JPEG2000
In principle coding standard JPEG2000 [4, 5, 11, 12, 13,14], the original image is 4Tpartitioned into rectangular non-overlapping tiles if the image is very large [1]. All tiles have exactly the same dimensions, except may be those at the boundary of the image [6]. 4T(Figure 1).4Tthen, is followed by the component Transformations step. After component transform, the tile-components are...