| 摘要 |
PROBLEM TO BE SOLVED: To accurately judge the quality of a quartz plate 2. SOLUTION: The quartz plate 2 as a specimen is photographed by a CCD camera 4, its image is fetcted by a processor 6, and the histogram of a relationship between a luminance and the number of pixels is created on the basis of the image. The processor 6 shifts the luminance one by one regarding fine adjacent different portions of the luminance in the histogram so as to find the mean value a1 to the mean value a17 of the number of pixels. A threshold- value setting part 6C in the processor 6 sets an accurate luminance in the histogram as a threshold value for each quartz plate 2 on the basis of the rate of change of the mean values in the number of pixels.
|
