Patent ID: 7415163

Claim:
A method of reducing block noise and mosquito noise in an image, said block noise and mosquito noise being caused at the time of decoding encoded, compressed image data on a block-by-block basis, the method comprising: dividing each of luminance component image data and color-difference component image data of said image data into blocks corresponding to the blocks created in the encoding and decoding of the image data; applying a first filtering step to the luminance component image data with each of pixels on the boundaries of the blocks being designated as a target pixel, thereby creating a first luminance component image data with the boundaries of the blocks smoothened; performing a second filtering step with each pixel of the first luminance component image data being designated as a target value, thereby creating a second luminance component image data with its entirety smoothened; creating edge image data by subtracting each pixel value of the second luminance component image data from a corresponding pixel value of the first luminance component image data; creating corrected edge image data with each difference value of the edge image data corrected under given conditions; creating a third luminance component image data by adding each offset value of the corrected edge image data to its corresponding pixel value of the second luminance component image data; and applying a third filtering step to the color-difference component image data with each pixel of the color-difference component image data being designated as a target pixel, thereby creating a first color-difference component image data with its entirety smoothened.