EXTERNAL-APPEARANCE INSPECTING METHOD

PROBLEM TO BE SOLVED: To provide an external-appearance inspecting method whereby it is prevented to identify erroneously as a defective pixel the pixel which is not corresponding to a true defective pixel existent in an inspected object, and it is made possible to identify also correctly as a defective pixel the pixel which is corresponding to a true defective pixel and has not been identified as the defective pixel in a first identifying process. SOLUTION: A central processor 7 so calculates the difference between the gradation value of each pixel of an inspected picture stored in an inspected-picture storage 6 and the gradation value of each pixel of the corresponding picture to the inspected picture which is stored in a reference-picture storage 6, as to judge whether the absolute value of the difference is larger than a first threshold α or not. The central processor 7 identifies the pixel having the absolute value of the difference larger than the first threshold α as a defective pixel. Next, with respect to each pixel falling in the scope separated from each defective pixel by a predetermined number of pixels, the central processor 7 so calculates the difference between the gradation value of the reference picture and the gradation value of the inspected picture as to judge whether the absolute value of the difference is larger than a second threshold β or not. The central processor 7 identifies further each pixel having the absolute value of the difference larger than the second threshold β as a defective pixel. COPYRIGHT: (C)2007,JPO&INPIT