| 摘要 |
<p>PURPOSE:To reduce the capacity of a delay means by providing a 2nd conversion means converting an output of a delay means into a correction value under a prescribed rule and a 1st conversion means indexing the quantization error in an encoder in a digital transmission system for a picture signal such as a television signal. CONSTITUTION:A compressor 52 outputs an index Ii(n) corresponding to a level of an output -epsiloni(n) of a subtractor 50. A frame memory 54 acts like a delay element by one frame and retards an output Ii(n) of the compressor 52. An expander 56 expands an output of the frame memory 54 to output a correction corresponding to the index Ii(n). Let the correction values be three as +a, 0 and -a, then two bits is enough per one picture element as the index and the capacity of the frame memory 54 is decreased by the share. Since the probability of appearance of the quantization error is biased in the vicinity of 0, a variable length code such as a Huffman code is used for the index to save the capacity of the frame memory 54.</p> |
