Image coding method, image coding and decoding method, image coding apparatus, and image recording and reproduction apparatus

摘要

An image coding apparatus according to the present invention is provided with, as shown in figure 4, a blocking circuit 401 for dividing an input image signal into two-dimensional blocks each comprising plural pixels; a frequency distribution verifier 408 for calculating the average and variance from a plurality of image feature data 402 to 407 and the frequency distribution of each feature data for each block in a predetermined period; a filter characteristic decider 409, a filter circuit 410, and an encoder 411. <??>In the image coding apparatus so constructed, the input image signal is divided into local regions each comprising plural pixels, the image feature data of each local region is extracted, the average and the variance of the extracted image feature data are calculated from the frequency distribution of the image feature data for a predetermined period, and a filter characteristic and a quantization step are decided for each local region according to the degree of singularity of each local region. Thereby, the quantity of generated codes can be controlled more precisely as compared with the conventional apparatus, and a portion of the decoded image where coding noise is conspicuous can be locally suppressed. <IMAGE>