Patent ID: 7539352

Claim:
An image filter for filtering a pixel of interest using said pixel of interest and its neighboring pixels, in which a first pixel group containing said pixel of interest, a second pixel group containing said first pixel group and a third pixel group containing said second pixel group are defined relative to said pixel of interest, said image filter comprising: a calculation part for calculating a first reference pixel value based on pixels contained in said first pixel group, and calculating a second reference pixel value based on pixels contained in said third pixel group; a judgment part for dividing said second pixel group into two sub-groups, and selecting one of said two sub-groups containing said pixel of interest as a target set, said two sub-groups including one sub-group containing pixels with pixel values greater than said second reference pixel value and the other sub-group containing pixels with pixel values smaller than said second reference pixel value; a selection part for selecting a pixel with a pixel value closest to said first reference pixel value as a corrective pixel from pixels contained in said target set; and an output part for outputting the pixel value of said corrective pixel as the pixel value of said pixel of interest.