Research On The Application Of The Wavelet Transform And Vector Quantization In Image Compression

Wavelet Transform is an excellent mathematical tool in image compression technique. The traditional DWT has bad performance when the image is non-smoothing. The Adaptive Wavelet Transform (AWT) can solve this problem, but it can't be used in the JPEG2000 standard. In order to solve this problem an improved AWT based on the DB9/7 is given. The Vector Quantization (VQ) is an efficient compression technique and has bright prospect. It has high compression ratio and simple coding process. The DWT-VQ image compression algorithm is quite popular in recent years. The application of DWT and VQ in image compression is studied in this paper and an algorithm which combines the AWT and VQ is given. The following work is done:1. To use the AWT algorithm in JPEG2000 standard, the AWT algorithm is studied and an improved AWT algorithm is given. The performance of the improved algorithm is contrasted with the original algorithm. The reconstruction and the PSNR are contrasted and the validity of the algorithm is tested by experiment. The result shows that it has good performance, especially when the image is non-smoothing.2. The LBG, PNN, PSO and LVQ algorithms are studied, and the performance of these codebook design algorithms are analyzed by contrasting the distortion and the complexity of these algorithms. The DWT is combined with these algorithms and the performance of these DWT- VQ algorithms are contrasted by experiment.3. The algorithm which combines the improved AWT algorithm and the VQ algorithm is given, and the validity of this algorithm is tested by experiment. The result shows that this algorithm can combine the advantage of the two algorithms and has excellent performance.