| 摘要 |
PURPOSE:To prevent production of mosquito noise by detecting a block in which mosquito noise production is predicted and dividing a quantization step size of the block more minutely than that of other block in a frame. CONSTITUTION:A differentiating processing obtaining a gradient of a signal level is applied to each picture element in a block, and the picture element is classified into groups of 'flat, intermediate, edge' from an obtained differentiating value based on a predetermined criterion. Then a mosquito noise prediction device 2 predicting a mosquito noise production block is placed after the noise filter 1 based on a prescribed criterion from the count of a number of picture elements included in the block belonging to each group and an MN signal is generated as to a block predicting the production of mosquito and sent to a quantizer 6. The quantizer 6 uses the MN signal to use a switch 63 which selects the signal into a QM 62 representing the step size finner. Thus, the production of mosquito noise is prevented. |
