| 摘要 |
PURPOSE:To improve the data compression efficiency and to reduce picture quality deterioration by controlling other block division based on discrimination of one block activity of signals in a correlation state when image data are subject to hierarchical coding. CONSTITUTION:In the image coder coding image data while dividing the data into plural hierarchical data having plural resolutions, a division threshold level for a chrominance signal is changed based on a block activity of a luminance signal as shown in figure. As an example, suppose that a 4th hierarchical video data D 44 are received. An output of a threshold level discrimination section 54G receiving an output of a luminance activity detection section 54F receiving an output of a luminance signal detection section 54E and an external input SL are given to a threshold level setting section 54H to decide the threshold level 54H and it is given to a threshold level discrimination section 54D receiving an output of a chrominance activity detection section 54C receiving an output of a chrominance signal detection section 54F to decide the chrominance signal threshold level 54D and an output of the 54D is given to a coding control section 54A, which applies block division to the image data and encodes the divided data. Thus, the block division suitable for a characteristic of an image signal is attained and picture quality deterioration such as color blotting is reduced. |
