Still Image Codec Based On Integer Wavelet Transform Research And Applications

Digital image compression is the key technology of different kinds of applications in digital image processing. In the past years, great processes have been made in digital image compression area. Digital image compression based on wavelet transform is becoming one of the most important trends of development in this field because of wavelet transform's excellent performance both in time and frequency domain. With the development of technology, more and more algorithms emerge and their capability of real-time processing is attracting more focus than ever before.This dissertation focuses on improving the performance of digital image compression system and implementing it. Two methods of saving time are considered: improvement of algorithm and optimization of platform.(1)Improvement of algorithm.The algorithm of digital image compression based on wavelet transform is divided into two segments: wavelet transform and coding of wavelet coefficients.First, an integer-to-integer wavelet transform using lifting scheme is adopted, which implements wavelet transform in time domain and is easier and faster to realize.Furthermore, a new algorithm of wavelet coefficients coding is introduced. Although zero-tree coding is the most classical and efficient method in wavelet coding area, it costs too much time for both encoding and decoding. Aiming at boosting the speed of processing, this dissertation introduces a wavelet coefficient coding method based on tree character plane, which has excellent performance and saves a lot of time by reducing several times of wavelet coefficients scanning to only once.This dissertation designs and implements a digital image compression system combining integer-to-integer wavelet transform and wavelet coefficient coding method based on tree character plane. After presenting the framework and process chart, this dissertation gave the method to realize it in detail, then realized it as software on PC and obtained satisfying performance. It is demonstrated that this system has excellent performance in both coding and real-time processing.(2)Optimization of platform. In order to ulitize the powerful capabilities of DSPs in digital image processing and make the processing more flexible and adaptive, this system is realized on TI's developing platform- TM320C6711DSK. Besides, several kinds of optimization method has been adopted to further improve the performance in terms of providing possibilities of real-time processing.