ON-LINE DIRT COUNTER

摘要

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 look-up table. The counter generates a dirt speck histogram and statistical data within a preselected time interval or area coverage.