Patent attributes
One-dimensional line data is produced based upon an evaluation area in image data obtained by imaging the area the slit light beam is irradiated. Each point data value included in the line data is obtained based upon each pixel value in a pixel array arranged in a Y-axis direction having the same X coordinates in the evaluation area. The point data value in the line data depends upon the result of the difference between the pixel values of the adjacent pixels in the pixel array. The affect by the reflected light of the slit light beam from the surface of the moving object is offset between the adjacent pixels, so that it is not reflected on the point data value. The point data value corresponding to the blocked state and the point data value corresponding to the non-blocked state can be made clearly different from each other.
