On-line dirt counter

摘要

PCT No. PCT/CA90/00168 Sec. 371 Date Oct. 28, 1992 Sec. 102(e) Date Oct. 28, 1992 PCT Filed May 23, 1990 PCT Pub. No. WO91/18281 PCT Pub. Date Nov. 28, 1991.The two-dimensional medium-pass filter principle is used to acquire a sharpened image initially In practice the sharpened image is obtained from the difference of a linear array signal of a partially out-of-focus image from another linear array signal of the same image but in focus. Integrated intensity of dirt specks higher than a user selected threshold are measured and accumulated. Each integrated intensity value is converted into its corresponding speck size with the use of a predefined fined look-up table. The counter generates a dirt speck histogram and statistical data within a preselected time interval or area coverage.