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1. 发明授权

US5699457A Image compression coder having improved bit rate control and block allocation 失效
标题翻译：具有改进的比特率控制和块分配的图像压缩编码器
公开(公告)号：US5699457A
公开(公告)日：1997-12-16
申请号：US88096
申请日：1993-07-02
申请人： Rutie Adar , Michael Gransky , Rafael Retter , Aharon Gill , Isaac Shenberg
发明人： Rutie Adar , Michael Gransky , Rafael Retter , Aharon Gill , Isaac Shenberg
IPC分类号： G06T9/00 , H04N1/41 , H04N7/26 , H04N7/30
CPC分类号： H04N19/42 , H04N19/115 , H04N19/126 , H04N19/14 , H04N19/149 , H04N19/172 , H04N19/176 , H04N19/60 , H04N19/124 , H04N19/13 , H04N19/146 , H04N19/91
摘要： A method of bit rate control and block allocation for discrete cosine transform (DCT) image signal compression includes the steps of (a) partitioning the image signals in blocks representing portions of the total image, (b) calculating DCT coefficients for image data in all blocks, (c) obtaining a measure of block activity (BACT) for each block based on DCT coefficients and for the total image activity (ACT) as a sum of the measures of all block activity, and (d) determining a code allocation factor (AF) for each block based on the ratio of block activity (BACT) to target code volume (TCV data) for the coded image data. Thereafter, step (e) includes allocating bits for each block using the allocation factor (AF) for each block and the target code volume (DCV data). Steps (a-d) are carried out with a first statistical pass through the image data, and step (e) is carried out in a second compression pass through the image data using the code allocation factor (AF) from step (d) and an estimation of unpredictable features for each block. Step (e) further includes comparing the estimation of unpredictable features to the accumulated actual code volume and adding extra bits to the allocation for at least the next block allocation and subtracting borrowed bits from at least the next block allocation.
摘要翻译：用于离散余弦变换（DCT）图像信号压缩的比特率控制和块分配的方法包括以下步骤：（a）在表示总图像的部分的块中划分图像信号，（b）全部计算图像数据的DCT系数块，（c）基于DCT系数和总图像活动（ACT）获得每个块的块活动度量（BACT）作为所有块活动的度量的总和，以及（d）确定代码分配因子（BACT）与编码图像数据的目标代码量（TCV数据）的比率对应于每个块的（AF）。此后，步骤（e）包括使用每个块的分配因子（AF）和目标代码量（DCV数据）为每个块分配比特。步骤（ad）通过图像数据进行第一次统计通过，并且使用来自步骤（d）的代码分配因子（AF）通过图像数据进行第二压缩传递中的步骤（e），并且估计每个块的不可预知的特征。步骤（e）还包括将不可预测特征的估计与累积的实际代码量进行比较，并将至少下一个块分配的额外比特添加到分配中，并从至少下一个块分配中减去借用的比特。

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