| 摘要 |
<p>PURPOSE:To prevent the degradation in vision characteristic of a reproduced image by unconditionally setting effective/ineffective information to effectiveness when most approximating block select information indicates a gray level block and threshold comparison information is outputted. CONSTITUTION:When threshold comparing means (threshold comparing part 19) outputs threshold comparison information indicating that the threshold level from a threshold generating means (threshold generating circuit 18) is higher than a prescribed value, an effectiveness setting means (AND gate 20) unconditionally sets effective/ineffective information from an effective/ineffective information generating means (effective/ineffective information generator 13) to effectiveness by said comparison information and information indicating the gray level block. Thus, a good encoding characteristic is obtained even for an input image whose motion is hard and threshold level of encoding control is inclined to rise, and the degradation in vision characteristic of the reproduced image is prevented without reducing the number of transmission frames even in case of an input image whose threshold of encoding control is inclined to fall.</p> |
