为了提高自动调焦算法的实时性,提出一种基于多尺度窗口的分段式自动调焦算法,首先使用小尺寸调焦窗口降低单幅图像清晰度值计算量,快速找到局部聚焦位置,然后以该位置作为二次调焦起点,适当增大调焦窗口范围,再以少量调焦步数完成全局聚焦位置的精确搜索。实验结果表明,该方法在保证成像系统准确聚焦的前提下,可有效降低量化图像清晰度所需的计算量,提升自动调焦的实时性。

To promote efficiency and real-time performance of auto-focus algorithm based on image processing, a multi-scale focusing window strategy is proposed. The focusing process is divided into two stages. At the first stage, a small focusing window is used to rapidly locate a local focusing position which is near the peak of sharpness evaluation function of original images. From that point, a bigger focusing window is adapted to accurately locate the global focusing position in fewer steps at the second stage. The experimental results indicate that the method can reduce the amount of calculation of the sharpness evaluation function and enhance the real-time performance of focusing process effectively.