Research On ROI Image Coding

With the rapid development of multimedia technology and Internet communication technology, the JPEG standard has been unable to fully meet the needs of users. JPEG2000 is a new standard for the compression of the still image established by the International Organization for Standardization (ISO) and the International Telecommunications Union (ITU). It is not only superior to any existing standard in compression efficiency, but also provides a series of new technology, Region of Interest (ROI) coding technology is one of them.Firstly, the principles and main algorithms of image compression technology, the significant status of wavelet analysis in the field of image compression are introduced. Then, the frame construction of JPEG2000 standard is analyzed. The two main techniques in the standard: wavelet transform and EBCOT are discussed seperatedly in detail.At last, According to the understanding of the main algorithm in JPEG2000 standard, the encoder part of JPEG2000 is realized with the C++ language. According to the experiment, the new generation standard for still image compression JPEG2000 is superior to the JPEG standard, especially in the low bit-rate.Secondly, based on the ROI image coding theory, two methods (Scaling- based method and Maxshift method) of JPEG2000 are discussed, and their coding capability are compared.Finally, based on the Maxshift method, a new method is proposed, which removes the high-frequency part of background (BG) of the Maxshift method. According to the experiment, the compression ratio is improved, the computer complexity is reduced and the ROI coding is optimized.