图像信息量的变化对自动对焦评价函数的影响

阐述了基于小波变换、拉普拉斯算子以及SPSMD（差分平方和函数）的三种自动对焦评价函数，采用数字仿真技术对不同特性的几组序列图进行了实验，分析了在图像信息量变化的情况下三种评价函数的特性。通过函数曲线图形能够清楚地发现，基于小波变换的自动对焦评价函数在图像信息量很少的情况下仍有很好的判断能力，有着最好的适应性和稳定性。

Performance of autofocus judgements in different quantity of information series images

This paper describes three different autofocus judgements based on wavelet transform, Laplacian operator and SPSMD.Then analyse the characteristic of these three judgements using the digital simulation technique. We used three group images which are changed fiom simple to complicated graphics, and compared the effection of these different autofocus judgements on the different group images. At last, the conclusion is given that the judgement based on wavelet transform has the best robust performance in different series images which contain different quantity of information.