关键词: 自动对焦, 图像清晰度, 评价函数, 灵敏度, 稳定性

Abstract:

Three common evaluation functions for automatic focusing were introduced. They were deviations function, gradient function and frequency-spectra function, the later two were optimized. Their merits and deficits in delicacy, stability and velocity were analyzed. And a multiple automatic focusing algorithm based on three-stages was proposed herein. It performs well in the video measuring system and can focus exactly and rapidly.

Key words: automatic focusing;image definition, evaluation function, delicacy, stability