| 摘要 |
PURPOSE:To correctly decide the still area of a picture to be an invalid block and to attain a highly efficient coding by deciding an effective/invalid block by the use of a differential signal in which a frequency band is limited. CONSTITUTION:A digital picture signal is inputted from an input terminal 1 and a predictive signal supplied from a predictive circuit is subtracted in a frame difference circuit 2. Then, a frame differential signal is quantized in a quantization circuit 3 and a quantizing central value is supplied to a frame addition circuit 4 and an entropy coding circuit 8. The differential signal between frames is inputted to a filter 6, a high frequency component is removed, thereafter, it is fed to an effective/invalid block decision circuit 7. The decision circuit 7 divides the differential signal into the blocks of a prescribed sized based on the band limited differential signal between frames to decide the effective or the invalid block. According to this decision result, the quantization circuit 3 and the coding circuit 8 are controlled. |
