Patent ID: 7738718

Claim:
A block decoding method for decoding and outputting data in a longitudinal direction, which decodes an input compressed datastream to obtain a decompressed image with a plurality of blocks in rows and columns, each said block consisting of pixels in a two-dimensional arrangement, and every K said blocks forming a minimum code unit row (MCUR), where K is an integer greater than one, the block decoding method comprising: a scanning step, which scans the compressed datastream to thus obtain a start address in the compressed datastream for each said MCUR, and direct current values corresponding to the K blocks of the MCUR; a decoding step, which longitudinally performs a Huffman decoding on the blocks in accordance with the start address of MCUR, thereby obtaining frequency values corresponding to the K blocks of the MCUR; a de-zigzag arranging step, which re-arranges the frequency values into a de-zigzag sequence; an inverse quantizing step, which performs an inverse quantization operation on the frequency values in accordance with an inverse quantization table; an inverse discrete cosine transform step, which converts the frequency values of the K blocks from frequency domain to spatial domain after the inverse quantization operation to thus obtain spatial domain coefficients corresponding to the K blocks of the MCUR; and a rotating step, which performs a rotation operation on the spatial domain coefficients.