Noise reduction method, noise reducing apparatus, medium, medium and program
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsTsuyoshi Maeda, Yoshio Seki
Life of this patent
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Abstract
A noise reduction apparatus in accordance with the present invention is configured to reduce mosquito noise while retaining edges by calculating the maximum value Y of the difference values of adjacent pixels in an area of M×N around a notice pixel by using a difference value calculator and a maximum value calculator, by controlling a pixel replacement device depending on Y and the difference value X from the notice pixel in the area of J×K narrower than the area of M×N, and by carrying out more intense smoothing depending on the magnitude of X with respect to Y, that is, when X is smaller than Y.
Claims22
A noise reduction method for the decoded signal of a digitally compressed image signal, comprising:
- a gradient calculation step of obtaining a predetermined gradient in an area of vertical M×horizontal N pixels (M and N are positive integers) around a notice pixel,
- a difference value calculation step of calculating, in an area of vertical J×horizontal K pixels (J and K are positive integers satisfying the relationships of J≦M and K≦N, respectively) around said notice pixel, (J×K−1) difference values between said notice pixel and pixels other than said notice pixel,
- a correction value calculation step of calculating correction values from said gradient obtained by said gradient calculation step and said (J×K−1) difference values obtained by said difference value calculation step, and
- an addition step of calculating a new notice pixel by adding said correction values to said notice pixel.
A noise reduction apparatus for the decoded signal of a digitally compressed image signal, comprising:
- gradient calculation means of obtaining a predetermined gradient in an area of vertical M×horizontal N pixels (M and N are positive integers) around a notice pixel,
- difference value calculation means of calculating, in an area of vertical J×horizontal K pixels (J and K are positive integers satisfying the relationships of J≦M and K≦N, respectively) around said notice pixel, (J×K−1) difference values between said notice pixel and pixels other than said notice pixel,
- correction value calculation means of calculating correction values from said gradient obtained by said gradient calculation means and said (J×K−1) difference values obtained by said difference value calculation means, and
- addition means of calculating a new notice pixel by adding said correction values to said notice pixel.
A noise reduction apparatus for the decoded signal of a digitally compressed image signal, comprising:
- gradient calculation means of obtaining a predetermined gradient in an area of vertical M×horizontal N pixels (M and N are positive integers) around a notice pixel,
- difference value calculation means of calculating, in an area of vertical J×horizontal K pixels (J and K are positive integers satisfying the relationships of J ≦M and K≦N, respectively) around said notice pixel, (J×K−1) difference values between said notice pixel and pixels other than said notice pixel,
- filter coefficient calculation means of calculating filter coefficient from said gradient obtained by said gradient calculation means and said (J×K−1) difference values obtained by said difference value calculation means, and
- filtering means of carrying out filtering on the basis of said calculated filter coefficients.
Dependencies are inferred from the claim text.