IMAGE CODING METHOD, IMAGE CODING / DECODING METHOD, IMAGE CODER, OR IMAGE RECORDING/REPRODUCING APPARATUS

摘要

An image coder comprises, as shown in the figure, a blocking circuit (401) for dividing an input image signal into two-dimensional blocks constituted of pixels, frequency distribution auditors (408) for calculating the averages and dispersions of the feature information on each block from image feature information (402 to 407) and from the frequency distribution of the feature information over a predetermined period, a filter characteristic determiner (409), a filter circuit (410), and a coder (411). In such an image coder, the input image signal is divided into local regions constituted of pixels, image feature information on each local region is extracted, the averages and dispersions of the extracted image feature information are calculated from the frequency distribution of the information over a predetermined period, and the filter characteristics and quantization step width of each local region are determined according to the specificity of each local region. Therefore, the amount of codes generated are controlled more minutely than conventional, and portions of a decoded image where coding noise is conspicuous can be locally prevented from being produced.