针对水下距离选通激光成像图像模糊导致自动聚焦难的问题, 提出了多分辨率爬山自动聚焦法, 解决了系统实时聚焦问题, 获得了高清晰度高质量图片。该方法利用图像的多分辨率原理, 通过空间采样处理形成不同分辨率采样层, 减少数据量, 降低图像处理时间, 系统完成聚焦处理时间降低到约为传统方法的一半。进而利用帧间相关性对当前帧和相邻前两帧分别以0.5, 0.3和0.2的加权系数进行加权计算, 获得当前帧的边缘检测清晰度值, 近乎以100%正确率解决爬山法由于局部峰值干扰错误判断可能收敛到局部最大值而导致聚焦失败的问题, 最后利用爬山法实现自动聚焦。针对此方法进行多次选通系统实验验证, 结果证明: 该方法能够保证自动聚焦的速度和精度, 提高系统聚焦判定的实时性、准确性和鲁棒性。

A real-time, accuracy and robustness multi-resolution mountain climb servo (MCS) auto focus method was proposed in order to solve real-time auto focus problem, and was obtained high clear high quality image because low clear low light images was difficult to realize auto focus in range-gated imaging system for underwater. The merits of this method were outstanding as follows. It reduced the amount of processing data and time by taking advantage of the image multi-resolution theory by spatial sampling of the current image and then formed different resolution sampling layers, which made the system possible to deal with auto focus more quickly as 1/2 time as traditional method. Thereby, the method calculated current frame weighted average edge detection image definition, which was determined by the correlation between current frame and two adjacent frames with 0.5, 0.3 and 0.2 coefficients before solving the error judge of interference maximum local peak. At last, the method realized the last operation auto focus by MCS. The repeated experimental verification of range-gated imaging system for underwater shows that the algorithms is capable of guaranteeing the auto focus speed and accuracy and improving the real-time, accuracy and robustness in focus determination.