| 摘要 |
PURPOSE:To suppress the increase in the number of pixels to be subjected to image processing, by subjecting a plurality of the pixel rows of pixel row groups, which are positioned so as to be separated from each other among a large number of pixel rows arranged in the longitudinal direction of a boundary, to the processing. CONSTITUTION:In such a case that a picture is limited, only the pixel rows positioned within a set range toward the y-axis direction becoming the up-and- down direction on the picture are removed from differentiation processing calculating the differential values of the brightness changes of said pixel rows to thin the pixel rows being a processing object in the longitudinal direction of the boundary L1 on a process side and a plurality of pixel row groups positioned so as to be separated from each other are subjected to processing. Only the pixels wherein the absolute values of the differential values are a threshold value or more are extracted. A large number of the straight lines passing said pixels are projected on a polar coordinates system by Hough transform processing and the frequency taking the same coordinates value is taken on a histogram and one straight line becoming the max. frequency is calculated.
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