Patent ID: 7893973

Claim:
An image processor that carries out image processing of document image data that includes a plurality of pixel data that are generated due to shooting of a document image by a two-dimensional image sensor, the image processor comprising: a pixel data converter that converts the document image data into luminance image data that includes a luminance component; a block image data-generator that splits each pixel data of the luminance image data into a plurality of blocks that include the same number of pixel data, and generates block image data that includes block pixel data wherein a maximum luminance value, among a luminance value of each pixel data of each block, is treated as the luminance value of the respective block pixel data; a change rate-calculating unit that sequentially calculates towards a single direction, with respect to the luminance value of the block pixel data in the single direction that is adjacent to a linear block pixel data cluster that includes the adjacent block pixel data in the single direction, a change rate of the luminance value of the block pixel data in other direction; a start point end point-setting unit that compares, with a predetermined change rate towards the single direction, an absolute value of each calculated change rate, sets as start point block pixel data of luminance change, upon the absolute value of the change rate exceeding the predetermined change rate, the block pixel data in the single direction among the adjacent block pixel data, and sets as end point block pixel data of luminance change, upon the absolute value of the change rate exceeding the predetermined change rate once again, the block pixel data in the other direction among the adjacent block pixel data; a block pixel luminance value-correcting unit that corrects, based on a start point luminance value of the set start point block pixel data and an end point luminance value of the set end point block pixel data, each luminance value of the block pixel data between the start point block pixel data and the end point block pixel data; a luminance value-substituting unit that calculates, among each block pixel data, an average value of each luminance value of an adjacent block pixel data cluster that includes a single block pixel data and block pixel data that are adjacent to the single block pixel data, and substitutes by the average value, the luminance value of the block pixel data, among the adjacent block pixel data cluster, wherein the luminance value is less than the calculated average value; a pixel luminance value-setting unit that sets, based on the luminance value of the block pixel data, the luminance value of each pixel data corresponding to the block pixel data, and generates post process luminance image data; and a reconverter that reconverts the generated post process luminance image data into the document image data.