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## An example

We use a two scale wavelet image as a simple to show the algorithm. The original image is shown in (a) of Figure .

The procedure of encoding together decoding for the image is listed as follows.

Dominant pass 1. The threshold T=16, and the quantization value is 1.5T=24. The output symbols are POS(18), ZTR(3), ZTR(6) and ZTR(5). The reconstruction values is 24, corresponding to the only positive significant coefficient 18. The subordinate list contains just one number 18. The coefficient maintained in the subordinate list is replaced by zero in the image, and the image is shown in (b) Figure .
Subordinate pass 1. One symbol is generated corresponding to the only coefficient (18) in the subordinate list, the symbol is 1, because 18 is larger than the threshold 16.
Dominant pass 2. The threshold is halved, i.e., T=8, and the quantization value is 1.5T=12. The output symbols are ZTR(3), IZ(6),ZTR(5), POS(8), POS(13), ZTR(-7) and ZTR(1). The reconstruction values is 24, 12, 12, corresponding to the numbers 18, 8, 13 in the subordinate list, and then the coefficients maintained in the subordinate list are replaced by zero in the image, and the image is shown in (c) Figure .
Subordinate pass 2. Three symbols are generated corresponding to the coefficients 18, 8, 13 in the subordinate list. The output symbols are 0,1 and 1.
Dominant pass 3. The threshold is halved again, i.e., T=4, and the quantization value is 1.5T=6. The output symbols are ZTR(3), POS(6),NEG(-5), NEG(-7), ZTR(1), NEG(-6), POS(4),ZTR(3) and and ZTR(-2). The reconstruction values is 24, 12, 12,6, 6, -6, -6, 6, corresponding to the numbers 18, 8, 13, 6, -5,-7,-6, 4 in the subordinate list, and then the coefficients maintained in the subordinate list are replaced by zero in the image, and the image is shown in (c) Figure .
Subordinate pass 3. Eight symbols are generated corresponding to the coefficient 18, 8, 13, 6, -5,-7,-6, 4 in the subordinate list. The output symbols are -1, 1, 1, 1, 1, 1, 1 and 1.

Next: Experimental Results Up: Embedded zerotree wavelet (EZW) Previous: Decoding
Andrew Doran
Cherry Wang
Huipin Zhang
1999-04-14