| 摘要 |
PURPOSE:To hold picture quality higher than a certain level by adaptively determining the degrees of hierarchical constitution, block by block, on a transmission side and generating plural layers. CONSTITUTION:The square sum integral value of the difference between in-block decoded data when a local decoder 5 is provided on the transmission side and all data of basic and extended layers are used and decoded and in-block decoded data when data are decoded while the extended layer data are considered to be zero is found. Its error corresponds to deterioration in picture quality, so the obtained square sum integral value is compared by a comparator 6 with a previously set threshold value and layers up to a minimum coefficient degree less than the threshold value are regarded as basic layers. In this case, when hierarchical structuring is performed right before quantization after orthogonal conversion in a hierarchical degree determination part 7, input image data before the orthogonal conversion are obtained by local decoding using all the data of the basic layers and extended layers. Internal difference arithmetic is therefore not necessary and only local decoding arithmetic in only the extended layers is needed. |
