| 摘要 |
A method of encoding two-dimensional original image data through fast cosine transformation FCT, the method including steps of inputting each block of N*N picture elements from the image data and transforming the block into N*N values of the first FCT coefficients by a first N*1 FCT circuit. The first N*1 FCT circuit uses multiplication factors of prescribed butterfly operations, the factors being multiplied by (square root)2. The method further includes storing the first FCT coefficients in a memory and transforming the first FCT coefficients into N*N values of second FCT coefficients by a second N*1 FCT circuit, the second N*1 FCT circuit using multiplication factors of prescribed butterfly operations, the factors being multiplied by (square root)2. The method further includes quantizing each of the second FCT coefficients using one of N*N corresponding values from a quantization table, the corresponding values being multiplied by 2. Finally, an entropy encoding of the quantized second FCT coefficients is performed, so as to produce compressed image data.
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