基于HDMI数码显微相机的自动曝光优化方法

Automatic Exposure Optimization Method for HDMI Digital Microscopy Cameras

针对HDMI数码显微相机在观测时由于不同目标反光水平不一致而出现过曝、曝光收敛速度慢、不稳定的问题,提出一种自动曝光优化方法。相较于传统的HDMI显微相机中的自动曝光控制方法,所提方法实现了基于感兴趣区域的曝光控制,可对RAW图像中的任意区域进行测光和亮度统计,拓展亮度统计的动态范围并实现基于不同目标的曝光控制,提升亮度统计的准确性,解决因目标过亮或者过暗而出现的过曝现象。同时设计了可变的曝光调节步长,该功能能够根据当前亮度水平动态调整曝光步长,实现曝光的粗调和细调,以平衡曝光收敛速度和曝光精确度。最终结合实际的相机进行实验,所提曝光控制优化方法相较于原有的自动曝光法曝光偏离度降低了一半,曝光收敛时间缩短了一半以上,最快能在4帧图像内完成曝光收敛。

An automatic exposure optimization method for mitigating overexposure,slow convergence speed,and instability in HDMI digital microscopy cameras due to the inconsistent reflection levels of different targets during observation is proposed.Compared with a traditional automatic exposure control method,the proposed method facilitates exposure control based on the region of interest,metering,and brightness statistics on any area in RAW images,thus expanding the dynamic range of brightness statistics and facilitating exposure control for different targets.In addition,the method improves the accuracy of brightness statistics and mitigates overexposure caused by extremely bright or dark targets.A variable exposure adjustment step size is set for the dynamic adjustment of exposure step size according to the current brightness level,achieving coarse and fine adjustment of exposure to balance exposure convergence speed and exposure accuracy.Finally,experiments were performed using actual cameras.The proposed method reduced the exposure deviation by half compared with the traditional automatic exposure method.The exposure convergence time was shortened by more than half,and the fastest exposure convergence was achieved within four frames of an image.