Efficient Photometric Alignment for Around View Monitor System Around view monitor system has become a typical advanced driverassistance system. Nevertheless, due to the differences between the lenses and sensors, the output image of around view monitor system inevitably has the visible brightness difference at the overlapping area of the images, and there are still obvious seams in the image mosaic. Photometric alignment aims to match the brightness of images under different illumination conditions and can be used to eliminate seams in the stitching image. The existing photometric alignment methods are mainly based on the gain compensation of three RGB channels, which not only increase the computational complexity but also affect the quality of output image. This paper proposes a new photometric alignment algorithm based on brightness channel and image fusion technology. Experimental results demonstrate that the seams in the final birdu0027seye view are smoothly compensated.

An Modified Realtime Photometric Calibration Algorithm Based on ORB Features * In order to improve the accuracy of direct visual odometry and SLAM algorithm under illumination changes, we propose an modified realtime photometric calibration algorithm based on ORB features. Firstly, we use more robust ORB features as input to a optimization framework to obtain scene points correspondences. Then, we establish the reprojection pixels intensity residual equation based on photometric image formation and feature matching results of the camera. Finally, the incoming frames are corrected by the camera response function, exposure time and vignetting estimation. The proposed approach is tested with the EuRoC dataset and TUM dataset respectively, and experimental results indicate that the exposure compensation and time cost performances of the proposed method are promising.