METHOD AND SYSTEM FOR DETECTING INCLINATION ANGLE OF DOCUMENT IMAGE

摘要

PROBLEM TO BE SOLVED: To detect an inclination (rotation) angle of a binary or multi-valued document image fetched in an inclined (rotated) state. SOLUTION: Parameter conversion is performed to (angle, distance) coordinates from (x, y) coordinates and pixel values of respective pixels of a binary or multi-valued image provided on an x-y image plane and an angle/ distance parameter chart in such a form that linearity can be easily extracted is prepared. From the angle/distance parameter chart, an angle to which straight lines are concentrated is detected as the inclination (rotation) angle of the binary or multi-valued image. At the time, a processing for which both of the case that whether the pixel value means a density or a luminance is known and the case that it is unknown are taken into consideration is performed.