Patent ID: 8659684

Claim:
An image processing apparatus comprising: a first gradation-conversion-characteristics calculating unit that calculates first gradation conversion characteristics for each of a plurality of areas of input image signals, each of the plurality of areas of the input image signals including at least one pixel, and the first gradation conversion characteristics being obtained by dividing pixel values of the input image signals after gradation conversion processing by pixel values of the input image signals before the gradation conversion processing, wherein the first gradation conversion characteristics represent amplification factors of the pixel values; a gradation conversion unit that performs gradation conversion on each of the areas of the image signals by using the first gradation conversion characteristics; a band-signal generating unit that generates a plurality of band signals having mutually different frequency bands by multi-resolution conversion processing from the image signals subjected to the gradation conversion by the gradation conversion unit, sizes of the plurality of band signals being smaller than sizes of the input image signals; a second gradation-conversion-characteristics calculating unit that calculates second gradation conversion characteristics for each of the areas of the image signals based on the first gradation conversion characteristics, the second gradation conversion characteristics being calculated by making sizes of the first gradation conversion characteristics the same as the sizes of the plurality of band signals, and the second gradation conversion characteristics being a function of each of the plurality of band signals and the amplification factors of the pixel values; a noise reducing unit that performs processing for noise reduction on each of the plurality of band signals by using the second gradation conversion characteristics calculated by the second gradation-conversion-characteristics calculating unit; and an image combining unit, that combines the band signals subjected to the processing for noise reduction by the noise reducing unit.