| 摘要 |
PROBLEM TO BE SOLVED: To automatically set an input data such as comparison pitch, threshold of comparative inspection or the like by calculating the comparison pitch by discrete Fourier transform, determining a standard deviation of difference in picture element by the comparison pitch, and taking a prescribed-number folded value of it as the threshold of comparative inspection. SOLUTION: The image of a color filter 13 is read by a line sensor 11 by the transmitted lighting from a light source 12. The image output is imparted to an image processing circuit 15 to provide a waveform subjected to discrete Fourier transform. This waveform has two peaks of width of each image of three colors (blue, red, green) and the width of three-color image. The width of three-color image is taken as comparison pitch to provide a highly precise comparison pitch. The luminous quantity is regulated to determine the comparison pitch, picture element number, and central value, this is repeated until a proper luminous quantity can be provided to provide an optimum luminous quantity for the inspection of the color filter. A standard deviation is determined for each picture element of the differential picture element, and a prescribed number-folded value of this standard deviation is taken as threshold of comparative inspection. |
