Recognizing Multiple Billboard Advertisements in Videos

The sponsors for events such as motor sports can install billboard advertisements at event sites in return for investments. Checking how ads appear in a broadcast is important to confirm the effectiveness of investments and recognizing ads in videos is required to make the check automatic. This paper presents a method for recognizing multiple ads. After obtaining point correspondences between a model image and a scene image using local invariants features, we separate the point correspondences of an instance of an ad by calculating a homography using RANSAC. To make the use of RANSAC feasible, we develop two techniques. First, we use the ratio of distances of descriptors to reject outliers and introduce a novel scheme to set a threshold for the ratio of distances. Second, we incorporate an evaluation on appearances of ads into RANSAC to reject the homographies corresponding to appearances of ads which are never observed in actual scenes. The detail of a recognition algorithm based on these techniques is shown. We conclude with experiments that demonstrate recognition of multiple ads in videos.