基于无参考结构清晰度的自适应自动对焦方法

摘要

An adaptive mountain-climb searching strategy based on No-Reference Structural Sharpness (NRSS) of single image is proposed for autofocus system. This new method utilizes the prior knowledge on defocusing amount provided by NRSS. If the imaging system is greatly defocused, a large step-size is used to approach the focusing position quickly;otherwise, a small step-size is used to locate the focusing position accurately. This method has the same focusing accuracy to mountain-climb strategy, and it greatly decreases the number of images and the number of decision makings that are required. The experimental results indicate that the proposed method improves the speed of autofocus about 50％.%针对自动对焦系统,提出了一种基于单帧图像无参考结构清晰度的自适应变步长爬山搜索策略.该方法利用了无参考结构清晰度可提供的离焦量先验信息:当离焦量大时,大步距粗调快速逼近准焦位置;当离焦量小时,小步距微调准确定位准焦位置.该方法在不降低调焦精度的情况下,大大减少了自动对焦所需的图像数量和决策次数.实际系统实验结果表明,新方法使自动对焦速度提高了50%以上.