Image inspection apparatus, image inspection method, image inspection program, computer-readable recording medium and recording device

An inspection method for capturing an image of a moving workpiece to perform visual inspection, the method comprising the steps of:

• simultaneously turning on three or more illumination sections at first reference timing, and capturing an image of the workpiece by a common imaging section whose imaging direction and relative position with the illumination section are adjusted in advance, to acquire a first reference image;
• turning on the three or more illumination sections one by one in a predetermined turning-on order, illuminating, from mutually different illumination directions at different turning-on timing, the workpiece moved from the time point of the first reference timing, and capturing one partial illumination image with respect to each illumination direction by the imaging section, to acquire a plurality of partial illumination images with different illumination directions;
• simultaneously turning on the three or more illumination sections at second reference timing, and capturing, by the imaging section, an image of the workpiece further moved from the time point of each of the turning-on timing, to acquire a second reference image;
• designating by a tracking target image specifying section a tracking target image which is included in the first reference image and is used for tracking a position of the workpiece;
• searching the tracking target image designated by the tracking target image designating section from the second reference image, and specifying a position including the tracking target image in the second reference image, to estimate a corresponding relation of pixels that correspond among each of the partial illumination images based on the specified position;
• generating an inspection image for photometric stereo by an inspection image generating section based on the estimated corresponding relation of each of the pixels of the partial illumination images;
• and
• performing visual inspection of the workpiece by use of the inspection image.

An image inspection program embedded in a non-transitory computer readable medium for capturing an image of a moving workpiece to perform visual inspection,

• wherein the program allows a computer to realize functions of:
• simultaneously turning on three or more illumination sections at first reference timing, and capturing an image of the workpiece by a common imaging section whose imaging direction and relative position with the illumination section are adjusted in advance, to acquire a first reference image;
• turning on the three or more illumination sections one by one in a predetermined turning-on order, illuminating, from mutually different illumination directions at different turning-on timing, the workpiece moved from the time point of the first reference timing, and capturing one partial illumination image with respect to each illumination direction by the imaging section, to acquire a plurality of partial illumination images with different illumination directions;
• simultaneously turning on the three or more illumination sections at second reference timing, and capturing, by the imaging section, an image of the workpiece further moved from the time point of each of the turning-on timing, to acquire a second reference image;
• designating a tracking target image which is included in the first reference image and is used for tracking a position of the workpiece;
• searching the designated tracking target image from the second reference image, and specifying a position including the tracking target image in the second reference image, to estimate a corresponding relation of pixels that correspond among each of the partial illumination images based on the specified position;
• generating an inspection image for photometric stereo by an inspection image generating section based on the estimated corresponding relation of each of the pixels of the partial illumination images;
• and
• performing visual inspection of the workpiece by use of the inspection image.