| 摘要 |
PURPOSE:To control production of mosquito noise by selecting a quantization width with respect to a DCT coefficient sensitive to mosquito noise to be a value resulting from multiplying a coefficient less than the unity with a quantization width given externally so as to quantize the DCT coefficient sensitive to mosquito noise in details. CONSTITUTION:A multiplier 4 multiplies a quantization width inputted from an input terminal 1 with a constant set to a switch 3 and the constant set to the switch 3 is a positive value less than the unity depending on a coding bit rate or the like. A contour area discrimination section 6 discriminates whether or not a coded block is a contour area and informs the result of discrimination to a selector control circuit 7. In this case, whether or not the DCT coefficient inputted from an input terminal 2 is resident in an area sensitive to mosquito noise is discriminated and the result of discrimination and that by the discrimination section 6 are ANDed and the result is informed to a selector circuit 5, which selects its output in response to a control signal of the circuit 7. Thus, production of mosquito noise is controlled. |
