A thesis submitted in pa1tial fulfillment of the requirements for the degree of Master of Engineering, School of Engineering and Technology

Thesis (M.Eng.) - Asian Institute of Technology, 2002

The JPEG2000 is a new image compression standard that provides better performances over the previous standards. One of the major parts of JPEG2000 is EBCOT (Embedded Block Coding with Optimized Truncation) algorithm, which is needed to encode all bitplanes of every codeblock into compressed passes. Then some compressed passes are truncated to achieve a particular desired bit-rate by using rate-distortion optimization. Obviously, there is no need to encode all bitplanes of every codeblock as in JPEG2000. The new algorithm is proposed based on the predefined path scanning method due to the need to reduce encoding time of JPEG2000. The key concept of the proposed algorithm is to encode bandplanes (every codeblock of each subband at arbitrary bitplane) according to the predefined path (significant order of bandplanes) until it reaches the desired bit-rate. And the proposed algorithm continually encodes some bandplanes in order to make more choices for truncation which produces the better quality of compressed image. Then rate-distortion optimization is carried out to truncate some compressed passes in order to achieve the desired bit-rate. The experimental results show that encoding time of the proposed algorithm outperforms JPEG2000, especially at low bit-rate, while PSNR has been maintained at almost the same level. Furthermore, the quality of compressed image and encoding time can be adjusted by the number of extended scanning bandplanes.