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    • 1. 发明申请
    • MOVING IMAGE CODING APPARATUS, MOVING IMAGE DECODING APPARATUS, CONTROL METHOD THEREFOR, COMPUTER PROGRAM, AND COMPUTER-READABLE STORAGE MEDIUM
    • 移动图像编码装置,移动图像解码装置,其控制方法,计算机程序和计算机可读存储介质
    • WO2005088977A1
    • 2005-09-22
    • PCT/JP2005/004851
    • 2005-03-11
    • CANON KABUSHIKI KAISHAKAJIWARA, HiroshiMAEDA, MitsuruSUZUKI, MasakiKISHI, Hiroki
    • KAJIWARA, HiroshiMAEDA, MitsuruSUZUKI, MasakiKISHI, Hiroki
    • H04N7/30
    • H04N19/64H04N19/169H04N19/17H04N19/184H04N19/46H04N19/61H04N19/63
    • This invention provides a technique of preventing errors from being gradually accumulated on the decoding side, while maintaining high scalability, even when a technique for transformation to subbands as a plurality of frequency components, like discrete wavelet transformation, is used for moving image coding. The image data of one input frame is decomposed into a plurality of subbands having different frequency components by a discrete wavelet transformation unit (101). A lower bitplane coding unit (109) codes, for each bitplane, predetermined lower bits of each coefficient data of a subband LL and the coefficient data of subbands other than the subband LL. The data of the upper bits of the subband LL is stored in a frame memory (105). A motion vector detection unit (107) detects a predicted value and motion vector on the basis of the decoded data of the subband LL in a preceding frame. A subtracter (103) obtains the difference between the detected predicted value and the current frame. A coefficient coding unit (104) codes the obtained difference. A motion vector coding unit (108) codes the motion vector. A multiplexing unit (111) multiplexes the code data obtained by the coding units (104, 108, 109).
    • 本发明提供了一种防止错误逐渐积累在解码侧的技术,同时保持高的可扩展性,即使将用于变换为多个频率分量的子带(如离散小波变换)的变换技术用于运动图像编码也是如此。 通过离散小波变换单元(101)将一个输入帧的图像数据分解成具有不同频率分量的多个子带。 低位平面编码单元(109)针对每个位平面编码子带LL的每个系数数据的预定低位和子带LL以外的子带的系数数据。 子带LL的高位的数据被存储在帧存储器(105)中。 运动矢量检测单元(107)根据前一帧中的子带LL的解码数据来检测预测值和运动矢量。 减法器(103)获得检测到的预测值与当前帧之间的差。 系数编码单元(104)对获得的差值进行编码。 运动矢量编码单元(108)对运动矢量进行编码。 复用单元(111)对由编码单元(104,108,109)获得的编码数据进行复用。
    • 2. 发明申请
    • MOVING IMAGE CODING APPARATUS, MOVING IMAGE DECODING APPARATUS, CONTROL METHOD THEREFOR, COMPUTER PROGRAM, AND COMPUTER-READABLE STORAGE MEDIUM
    • 移动图像编码装置,移动图像解码装置,其控制方法,计算机程序和计算机可读存储介质
    • WO2005088976A1
    • 2005-09-22
    • PCT/JP2005/004850
    • 2005-03-11
    • CANON KABUSHIKI KAISHASUZUKI, MasakiMAEDA, Mitsuru
    • SUZUKI, MasakiMAEDA, Mitsuru
    • H04N7/30
    • H04N19/63
    • In this invention, even if final code data is to be generated by selectively discarding code data for each bitplane, errors due to bitplane rounding down operation can be suppressed from being gradually accumulated in predicted data such as P- and B-pictures, thereby preventing a deterioration in image quality. For this purpose, a block segmentation unit (31) segments an input frame into a plurality of blocks, and supplies the respective blocks to a difference computing unit (32). The difference computing unit (32) outputs the blocks to a DWT unit (33) without any change when the intra-frame coding mode is set. When the inter-frame coding mode is set, the difference computing unit (32) outputs the result obtained by computing a difference from predicted data from a motion compensation unit (42) to the DWT unit (33). The frequency component data obtained by the DWT unit (33) and a quantization unit (34) is entropy-coded by an entropy coding unit (35), and a bitplane formed by bit information at the bit position of each component value is coded. A bitplane round-down unit (36) rounds down the code data of bitplanes from the least significant position to an upper bit position such that the resultant code amount becomes equal to or less than a target code amount. A code forming unit then generates code data. Only when the intra-frame coding mode is set, a dequantization unit (39) and inverse DWT unit (40) are executed to update a frame memory (41).
    • 在本发明中,即使通过选择性地丢弃每个位平面的代码数据来生成最终代码数据,也可以抑制由于位平面舍入运算引起的错误,从而在诸如P图像和B-图像的预测数据中逐渐累积,从而防止 图像质量下降。 为此,块分割单元(31)将输入帧分割为多个块,并将各个块提供给差分计算单元(32)。 当设置帧内编码模式时,差分计算单元(32)将块输出到DWT单元(33)而没有任何改变。 当帧间编码模式被设置时,差分计算单元(32)将通过计算来自运动补偿单元(42)的预测数据的差异获得的结果输出到DWT单元(33)。 由DWT单元(33)和量化单元(34)获得的频率分量数据由熵编码单元(35)进行熵编码,并且对每个分量值的位位置处的位信息形成的位平面进行编码。 位平面舍入单元(36)将位平面的代码数据从最低有效位置向下舍入,使得所得到的代码量变得等于或小于目标代码量。 代码形成单元然后生成代码数据。 仅当帧内编码模式被设置时,执行去量化单元(39)和反向DWT单元(40)来更新帧存储器(41)。