摘要： 为实现快速精确的聚焦,减少反向回程间隙对自动聚焦的影响,提出一种变步长的分段调焦自动控制策略。通过减少反向运动的次数,实现粗调与精调相结合的快速精确自动聚焦。以评价函数的变化率作为判定函数,以当前评价点前5点的平均变化率为阈值,粗聚焦阶段以大步长进行粗略调焦,达到快速聚焦的目的,精聚焦阶段以小步距精确调焦,减少反向调整运动,从而达到精确聚焦的目的。实验结果表明,该策略能够减少反向回程误差的影响,克服局部极值,实现快速精确的聚焦。

关键词: 自动聚焦, 图像清晰度, 评价函数, 聚焦函数, 函数变化率

Abstract: In order to achieve fast and accurate autofocus and reduce the effect of reverse backlash on autofocus,by using variable step and subsection control,an automatic focusing strategy is proposed in this paper.Through reducing the number of reverse motion,the focusing control method realizes both rough and fine adjustment in automatic focusing.The changing rate of the evaluation function is used as the judging function and the average changing rate of the first 5 points before the current point as the threshold.In rough focusing stages,fast focusing is achieved by adopting the large step.In fine focusing stages,a small step is used and reverse adjustment is reduced,thus achieving fine focusing.Experimental results show that the strategy is able to reduce the reverse backlash error,overcome local maxima and achieve rapid and accurate focusing.

Key words: automatic focusing, image definition, evaluation function, focusing function, function change rate

中图分类号: 

• TP391