Gradient-based Camera Exposure Control for Outdoor Mobile Platforms

We introduce a novel method to automatically adjust camera exposure for image processing and computer vision applications of mobile robot platforms. Since most image processing algorithms heavily rely on low-level image features, which are largely based on local gradient information, we consider a gradient quantity to determine a proper exposure level, so that a camera is able to capture important image features robust to illumination conditions. We extend it to multi-camera system and present a new control algorithm to achieve both brightness consistency between adjacent cameras and a proper exposure level for each camera. We implement our prototype system with off-the-shelf machine vision cameras and demonstrate the effectiveness of the proposed algorithms on practical applications: pedestrian detection, visual odometry, surround-view imaging, panoramic imaging, and stereo matching.