Patent ID: 8208171

Claim:
An image reading apparatus comprising: a reader operable to read an image formed on a sheet to acquire RGB values of pixels that constitute the image, by using a sheet-through method; an extractor operable to compare an RGB value of each target pixel in the image with an RGB value of a neighboring pixel thereof to judge whether a difference therebetween is no less than a prescribed threshold, and extract the target pixel as a line-shaped noise candidate pixel if the difference is no less than the prescribed threshold and the target pixel constitutes a series of line-shaped noise candidate pixels extending in a feeding direction of the sheet; a determiner operable to calculate, for each of the R, G and B components included in the RGB value of the line-shaped noise candidate pixel, a difference from the corresponding one of R, G and B components included in an RGB value of each of surrounding pixels included in a surrounding area of the line-shaped noise candidate pixel, and determine the line-shaped noise candidate pixel as a line-shaped noise pixel if (i) only one of the components has a difference that is no less than a prescribed value, or (ii) only two of the components have a difference that is no less than a prescribed value, and the two of the components are considered as substantially the same; and a corrector operable to correct the RGB value of the line-shaped noise pixel based on an RGB value of at least one of surrounding pixels included in a surrounding area of the line-shaped noise pixel, wherein the corrector defines a plurality of blocks throughout the surrounding area of the line-shaped noise pixel by averaging R, G and B components among each prescribed number of pixels included in the surrounding area of the line-shaped noise pixel, extracts one of the blocks whose non-noise color component has a smallest difference from a non-noise color component of the line-shaped noise pixel, and corrects the RGB value of the line-shaped noise pixel by replacing with an RGB value of the extracted one of the blocks, where the non-noise color component is any component of the RGB value of the line-shaped noise pixel other than a noise color component, and the noise color component is a component that has the difference that is no less than the prescribed threshold.