Block decoding method and system capable of decoding and outputting data in a longitudinal direction
AssigneeSunplus Technology Co., Ltd.
InventorsKuo-Kuang Keng, Wen-Cheng Ho, Jyh-Kai Chang
Life of this patent
Estimating the term…
Abstract
A block decoding method and system capable of decoding and outputting data in a longitudinal direction, which obtains a start address in an input compressed datastream for each block of a decompressed image by a pre-scanned compressed datastream such that the system can obtain 90°-rotated blocks by performing a Huffman decoding in a longitudinal direction, a 90°-rotated zigzag arrangement, an inverse quantization and an IDCT. Since the decoding direction is identical to the output direction of a printer, only a desired column of blocks of the decompressed image is temporarily stored for output and accordingly required memory size is relatively reduce.
Claims28
A block decoding method capable of 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 block consisting of pixels in a 2-D arrangement, the method comprising the steps:
- a pre-scanning step, which pre-scans the compressed datastream to thus obtain a start address of each block in the compressed datastream;
- a decoding step, which longitudinally performs a Huffman decoding on each block in accordance with its start address, thereby obtaining 1-D arrangement frequencies of each block;
- a reverse zigzag arranging step, which arranges the frequencies of each block in a reverse zigzag sequence of lower, right upper, right and left lower, and repeats the sequence until the frequencies are arranged completely;
- an inverse quantizing step, which performs an inverse quantization on the frequencies of each block arranged in accordance with a rotated inverse quantization table obtained by rotating an inverse quantization table of the compressed datastream by 90 degrees;
- and
- an inverse discrete cosine transform (IDCT) step, which converts all blocks from frequency to spatial domain after the inverse quantization, thereby obtaining spatial blocks.
A block decoder capable of decoding and outputting data in a longitudinal direction, which decodes an input compressed datastream to obtain a decompressed data with a plurality of blocks in rows and columns, each block consisting of pixels in a 2-D arrangement, the decoder comprising:
- a pre-scanning device, which receives the compressed datastream for pre-scan to thus obtain a start address of each block in the compressed datastream;
- a decoding device, which longitudinally performs a Huffman decoding on each block in accordance with its start address, thereby obtaining 1-D arrangement frequencies of each block;
- a reverse zigzag arranging device, which is connected to the decoding device for arranging the frequencies of each block in a reverse zigzag sequence of lower, right upper, right and left lower, and repeats the sequence until the frequencies are arranged completely;
- an inverse quantizer is connected to the reverse zigzag arranging device for performing an inverse quantization on the frequencies of each block arranged in accordance with a rotated inverse quantization table obtained by rotating an inverse quantization table of the compressed datastream by 90 degrees;
- and
- an IDCT device, which is connected to the inverse quantizing device for converting all blocks from frequency to spatial domain after the inverse quantization, thereby obtaining spatial blocks.
A block decoding method capable of decoding and outputting data in a longitudinal direction, which decodes an input compressed datastream to obtain a decompressed data with a plurality of blocks in rows and columns, each block consisting of pixels in a 2-D arrangement, the method comprising the steps:
- a pre-scanning step, which pre-scans the compressed datastream to thus obtain a start address of each block in the compressed datastream;
- a decoding step, which longitudinally performs a decoding on each block in accordance with its start address, thereby obtaining 1-D arrangement frequencies of each block;
- a reverse zigzag arranging step, which arranges the frequencies of each block in a reverse zigzag sequence;
- an inverse quantizing step, which performs an inverse quantization on the frequencies of each block arranged in accordance with a rotated inverse quantization table obtained by rotating an inverse quantization table of the compressed datastream by 90 degrees;
- and
- an IDCT step converts all blocks from frequency to spatial domain after the inverse quantization.
A block decoder capable of decoding and outputting data in a longitudinal direction, which decodes an input compressed datastream to obtain a decompressed data with a plurality of blocks in rows and columns, each block consisting of pixels in a 2-D arrangement, the decoder comprising:
- a pre-scanning device, which receives the compressed datastream for pre-scan to thus obtain a start address of each block in the compressed datastream;
- a decoding device, which longitudinally performs a decoding on each block in accordance with its start address, thereby obtaining 1-D arrangement frequencies of each block;
- a reverse zigzag arranging device, which is connected to the decoding device for arranging the frequencies of each block in a reverse zigzag sequence;
- an inverse quantizer, which is connected to the reverse zigzag arranging device for performing an inverse quantization on the frequencies of each block arranged in accordance with a rotated inverse quantization table obtained by rotating an inverse quantization table of the compressed datastream by 90 degrees;
- and
- an IDCT device, which is connected to the inverse quantizing device for converting all blocks from frequency to spatial domain after the inverse quantization, thereby obtaining 2-D spatial blocks.
Dependencies are inferred from the claim text.