Smooth Side-Match Classified Vector Quantizer with Variable Block Size IEEE Transaction on image processing, VOL. 10, NO. 5, MAY 2001 Department of Applied Mathematics National Chung Hsing University Shiueng Bien Yang and Lin Yu Tseng
Outline Introduction Basic Algorithm Smooth Side-Match Method with Variable Block Size Genetic Clustering algorithm Experimental Results Conclusion
Introduction The evolution of SMVQ SMVQ SMVQ with CVQ SSM-CVQ Feature of SSM-CVQ Variable block size Smooth side-match method Genetic clustering algorithm is applied on codebooks generation
Basic algorithm SMVQ
Basic algorithm SMVQ with CVQ (encoder)
Basic algorithm SMVQ with CVQ (decoder)
Smooth Side-Match Method with Variable Block Size Variable Block Size Image Compression with Variable Block Size Segmentation Quadtree is used to address blocks of different sizes Smooth side-match method Diagonal basic blocks Smooth side-match distortion
Image Compression with Variable Block Size Segmentation
Quadtree is used to address blocks of different sizes
Block size and codebooks Blocks of sizes of 16x16 and 8x8 and 4x4 with low variance are low-detail blocks Use three master codebooks 4x4 8x8 16x16 Blocks of size of 4x4 with high variance are high-detail blocks Use CLUSTERING algorithm, we have q classes and q master codebooks for each class Total : 3 + q master codebooks
Diagonal basic blocks Diagonal blocks are encoded first. In the experiments, the number of the basic blocks required is approximately 25% to 28% of that of the conventional SMVQ.
Smooth side-match distortion (1) The encoded is divided into two parts Upper triangular region Lower triangular region Problem of SMVQ Different, dif(e, f) is defined as dif(e, f) = (gray level of e) – (gray level of f)
Smooth side-match distortion (2) Upper triangular region
Smooth side-match distortion (3) Lower triangular region
Genetic Clustering Algorithm (1) First Stage Use nearest neighbor (NN) algorithm to reduce the computation time and space in the second stage. (1) (2) (3) (4) Let the connected components be denoted by
Genetic Clustering Algorithm (2) Second Stage Use genetic algorithm to find an appropriate number of clusters. Initialization Step chromosome (string): numbers of 1 ’ s in the strings almost uniformly distributes within [1,m]
Genetic Clustering Algorithm Data Representation Chromosome Gene Individual
N individuals Population Size=N N strings is randomly generated.
Genetic Clustering Algorithm Evolution Processes 1. Self Reproduction 2. Crossover 3. Mutation
Genetic Clustering Algorithm Fitness Function
Genetic Clustering Algorithm Self Reproduction if k=
Genetic Clustering Algorithm Crossover Set Probability of crossover Position q Randomly generate If Position= q
Genetic Clustering Algorithm Mutation Set Probability of mutation Randomly generate If
Experimental results High-detailed Blocks : why 28 edge-classifiers Outside image: Lena & F-16 The PSNRs of the coding for Lena SSM-CVQ outperforms the others in both the PSNR & the bit rate
High-detailed Blocks : why 28 edge-classifiers
Outside image: Lena & F-16 JPEG Lena SMVQ with CVQ
The PSNRs of the coding for Lena CLUSTERING is best !
SSM-CVQ outperforms the others in both the PSNR & the bit rate
Conclusion The CLUSTERING clusters the appropriate number of clusters. Low-detail blocks could reduce bit rates High-detail blocks and smooth side- match distortion could increase quality