NOISE REDUCTION APPARATUS, METHOD AND COMPUTER- READABLE RECORDING MEDIUM

A noise-reduction apparatus includes an image-noise-reduction means having an operation means and a judgment means. The operation means shifts the level of the signal-value of a target-pixel so that an average of the signal-values of the target-pixel and pixels in a predetermined area in the vicinity of the target-pixel becomes a value at the origin of a color-space of each of a plurality of color-components, performs an operation for noise-reduction processing on the target-pixel and restores the level of the signal-value thereof based on the shifted level. The judgment means estimates a noise-amount of the target-pixel, calculates a statistic representing the noise of the target-pixel based on the signal-values of the target-pixel and the pixels in the predetermined area, compares the estimated noise-amount and the statistic, and determines, based on the result of comparison, which of the estimated noise-amount and the statistic to use for the operation of noise-reduction processing.