不同对比度下自适应的自动调焦新算法

针对大多数自动调焦函数不能克服对比度变化引起的调焦曲线失去理想特性、陷入局部极小值甚至失去单峰性等问题,介绍了Zernike正交矩,分析了各阶Zernike矩的调焦函数曲线并且提出了一种新的基于Zernike正交矩的自动调焦算法,定义了此算法的公式.与几种常用自动调焦函数在不同对比度条件下进行了调焦效果的比较分析,验证了通过调整各阶Zernike矩的权重系数、可以灵活变换调焦公式,能够适应不同对比度下的调焦过程.实验比较了基于Zernike正交矩的自动调焦算法应用于完全对称型物体和非对称型物体时焦效果的差别,证明了该算法应用于圆形或球状等完全对称型的物体时调焦效果较好.

Adaptive Autofocus Technique Under Different Contrast

For most of the auto-focus function's problems of focus curve losing desirable characteristics ,falling into local minum value and even losing single peaks,which are caused by changes in contrast,Zernike orthogonal moments was introduced and the focus curves were analyzed.A new auto-focusing algorithm was presented which based on Zernike orthogonal moments and the algorithm's formula was defined.Compared with the focusing effect of several commen auto-focus funtions under different contrast,the algorithm can adapt to different contrast under the focusing process by adjusting the weighting coefficients to change the formula.The experiment compared the algorithm focus curves' difference between completely symmetric objects and non-symmetric objects,proved that the algorithm is more effective for the completely symmetric objects such as the round or spherical objects.