To realize noise reduction with less image quality deterioration without mis-detection of S/N, based on a local characteristic of an image.
A local S/N detection section 200 obtains 2-dimension S/N and 3-dimension S/N for each block of an input image subject to block processing by a block processing circuit 100 and uses the S/N with less noise in both the S/N ratios for a local S/N of a concerned block. A global S/N detection section 400 collects the local S/N as to an entire input image and uses a most frequent value as the global S/N. A threshold setting section 500 sets a threshold in response to an image of each block according to the S/N with less noise in the local S/N and the global S/N. A noise reduction section 600 replaces a pixel value of a processing object pixel with a mean pixel value of a pixel whose difference from a pixel value of the processing object pixel is a threshold or below set to a block to which the processing object pixel belongs among pixels in the vicinity of the processing object pixel in an input image.
NAEMURA MASAHIDE
FUKUDA ATSUSHI
MIZUTANI TADANOBU
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