| 摘要 |
A video camera output signal is digitized by an analog-to-digital converter (ADC) and the digitized video frame stored in memory. The stored frame is high-pass spatially filtered and the filtering result is subjected to a non-linear point transform to suppress to zero less bright pixel samples. The grey scale values of the remaining pixels are summed to produce a summation value. Different focussed states have different summation values. The maximum summation value represents the point of optimum focus, and the system reaches the maximum value by changing the focus state of the optics, recomputing the grey scale sum and repeating the process until a global maximum grey scale summation value is reached, regardless of the initial focus state.
|
