| 摘要 |
PURPOSE: To reduce mosquito noise by changing a control value giving the characteristics of distortion reducing processing at a distortion reducing processing means for each picture element based on the gradient value of a picture element value at an attentional picture element. CONSTITUTION: The transmitted signal is decoded in variable length code by a variable length code decoder 220, inversely quantized by an inverse quantizer 205 and transformed by an inverse discrete cosine transformer(IDCT) 206. By the encoding system of the decoded image, a selector 210 is switched and added by an adder 207 to obtain the decoded image. The local gradient of an object picture element on the decoded image is calculated by a gradient measuring means 101, and a control means 102 controls a distortion reducing processing means 104 based on that calculated gradient value. Namely, since the mosquito noise stands out at a flat part near a sharp edge, especially, near a stepwise edge consisting of a flat part and an edge part, distortion remaining at the flat part around the edge is reduced while keeping the edge to be changed. |
