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【正文】 1 12 13814 1 12 1 12 1 16 43 1 12 1 13 1 13 1 13 1 12 12 12 1 18 1 18 38 1 18 13815 1 13 1 16 1 13 42 56 1 12 1 12 1 1 1 35 42 42 1 12 1 12 138 9 1616 1 16 1 16 1 13 37 55 55 1 12 1 1 1 35 42 78 78 106 106 11 11VQ index table for a 64?64 image Search Order Coding algorithm 5 4 6 5 4 4 6 7 6 5 7 ： initial position ： search path ： original direction HuChang algorithm ? Order by the mean of elements of codeword in codebook – the accept offset is ?2 (2 bits) ? 00 ? +1 ? 01 ? +2 ? 10 ? 1 ? 11 ? 2 The index value of the last coded block is 124. The index value of coding block is 126. 126124=2 ? 01 Motivation Localitybit rate better Improved HuChang algorithm Original codebook Reorder codebook codeword Experimental results Bite Rate (Codebook size =128, BR= bit per pixel) Hu Chang Our Enhance Lena F16 Toys Tiffany Average bite rate Bite Rate (Codebook size =256, BR= bit per pixel) Hu Chang Our Enhance Lena F16 Toys Tiffany 0. 3157 Average bite rate 0. 3254 Bite Rate (Codebook size =512, BR= bit per pixel) Hu Chang Our Enhance Lena 0. 4563 0. 3862 F16 0. 4555 0. 3986 Toys 0. 2955 0. 2588 Tiffany 0. 3899 0. 3592 Average bite rate 0. 3993 0. 3507 % better than HuChang’s method % better than HuChang’s method % better than HuChang’s method Index Searching Algorithm with Index Associated List (ISAIAL) ? Similarity between neighbor block ? Index associated list ? Use some different associated index table generation scheme to get better bit rate. Index Searching Algorithm with Index Associated List (ISAIAL) (coding) Find the index value of representative codeword by determining the closest Euclidean distance between input vector and all codewords in codebook Input the image block in order Is the index value equal to the index value of left or upward block? Type 1 Compare with the associated index list which corresponds to codeword index value of the previous block Is there exist the same index value? Type 2 Type 3 True True False False 00 denotes the encoding block and left block have the same index value. 01 denotes the encoding block and upward block have the same index value. 10 + index value of the encoding block 11 + index value of the encoding block BR=[Con(1)x(2)+Con(2)x(2+r)+Con(3)x(2+p)] / (MxN) Con(i) = the number of the index value in type i, 1= i =3 r : the number of bits determined by index associated list p : the number of bits determined by Huffman coding。 % better than conventional VQ ISAIAL experimental results(一 ) Bite Rate (Codebook size =512, BR= bit per pixel) . Hu Chang Method A Method A (fixed) Lena F16 Toys Tiffany Barb Gold Average bite rate % better than 、 % better than Hu – Chang’ method 。 % better than conventional VQ How to generate the index associated list(IAL)? 0 1 2 . . . n1 n2 . . . 0 1 2 … n2 n1 P0~Pn1 denote the occurrence probability when the index value is different
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