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AssigneesKokusai Denshin Denwa Kabushiki Kaisha, NEC Corporation, Fujitsu Limited, Nippon Telegraph and Telephone Corporation
InventorsMasahide Kaneko, Atsushi Koike, Mutsumi Ohta, Kiichi Matsuda, Naoki Mukawa, Yoichi Kato
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In an encoding system responsive to a sequence of coefficient signals which results from a predetermined linear transform and which is divided into a sequence of blocks, anterior processing is carried out prior to quantization about the coefficient signals in each block to determine a significant area of the coefficient signals by comparing each level of the coefficient signals with a threshold level. Only the coefficient signals within the significant area are judged to be valid and produced as a sequence of significant coefficient signals from a classifying circuit (20) to be quantized by a quantizer (15) into a sequence of quantized signals. The quantized signal sequence is subjected to posterior processing to produce a sequence of encoded signals. The significant area may be decided by the use of a selected one of zone detection, zigzag scanning, and adaptive scanning. In the posterior processing, the quantized signals may be encoded into the encoded signals by the use of a plurality of code sets or tables.
In an encoding system for use in encoding a sequence of digital signals into a sequence of encoded signals, said digital signal sequence being subjected to a predetermined linear transform into a sequence of coefficients which is divided into a sequence of blocks and which is produced as a sequence of coefficient signals, said encoding system comprising anterior processing means responsive to said coefficient signal sequence for processing said coefficients in the respective blocks into a sequence of preliminary processed signals, quantizing means coupled to said anterior processing means for quantizing said preliminary processed signals into a sequence of quantized signals, and posterior processing means for processing said quantized signal sequence into said encoded signal sequence, the improvement wherein said anterior processing means comprises:
In an encoding system for use in encoding a sequence of digital signals into a sequence of encoded signals, said digital signal sequence being subjected to a predetermined linear transform into a sequence of coefficients which is divided into a sequence of blocks and which is produced as a sequence of coefficient signals, said encoding system comprising anterior processing means responsive to said coefficient signal sequence for processing said coefficients in the respective blocks into a sequence of preliminary processing signals, quantizing means coupled to said anterior processing means for quantizing said preliminary processed signals into a sequence of quantized signals, and posterior processing means for processing said quantized signal sequence into said encoded signal sequence, the improvement wherein said posterior processing means carries out variable length encoding of said quantized signal sequence to produce variable length codes as said encoded signals and comprises:
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