IMAGE PROCESSING METHOD, IMAGE PROCESSOR, PROGRAM, AND RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To provide an image processing method that performs density correction of an image having illumination unevenness irrespective of kinds of tires and tire surface states, and to provide an image processor, a program, and a recording medium therefor.

SOLUTION: A control unit 12 calculates a quadratic function of an approximate parabola with simultaneous equations for calculating a density function by using a least square method. If a secondary coefficient (a) of the quadratic function is larger than a threshold, the control unit 12 newly calculates a density function by replacing density of pixels in an excluded region with average density of pixels in a non-excluded region. Then, the control unit 12 adds a level raising constant obtained based on minimum density shown by the calculated density function to a captured image and the density function. Finally the control unit 12 replaces density of pixels in a region where a density ratio of density of the captured image to which the level raising constant is added and density shown by the density function to which the level raising constant is added is in an exclusion density ratio region with average density of pixels in a non-exclusion density ratio region, and recalculates the density function. Thus the captured image is corrected with a density shown by the recalculated density function.

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