| 摘要 |
PURPOSE:To narrow transmission band by making the rate of thinning of subsampling large in a stationary part in which the width of variation of luminance level is small and making the rate of thinning of subsampling small in a part in which the width of variation of luminance level is large. CONSTITUTION:A dynamic range detecting circuit 3 and a variable sampling circuit 4 are provided, and when the dynamic range DR of a block is large, variation of the image of the block is large, and accordingly, subsampling is not made. As the smaller the dynamic range DR, the smaller variation of the image of the block, the rate of subsampling is made lower. For instance, either of two kinds, 1/2, 1/4 of sampling is used. By this adaptive subsampling, sampling frequency can be lowered evenly without causing turning back distortion. |
