Scene Analysis using Camera Arrays
We have developed new methods for scene analysis using camera arrays. Scene analysis involves segmenting, detecting, and tracking objects from a stream of images. Scene segmentation is an important task in many applications such as surveillance, human-computer interaction, and the entertainment industry. We explore the advantages of using a camera array instead of a single camera for that purpose and find that for segmentation, a camera array is superior to a single camera.
Background & Objective: Automatic, real-time, passive, and robust image segmentation is a long-standing problem in computer vision. To date no algorithm achieving these goals has been presented. We propose the first automatic, real-time, passive, and robust image segmentation system using a camera array.
Technical Discussion: We present an algorithm and a system for high-quality natural video matting using a camera array. The system uses high frequencies present in natural scenes to compute mattes by creating a synthetic aperture image that is focused on the foreground object, which reduces the variance of pixels reprojected from the foreground while increasing the variance of pixels reprojected from the background. We modify the standard matting equation to work directly with variance measurements and show how these statistics can be used to construct a trimap that is later upgraded to an alpha matte. The entire process is completely automatic, including an automatic method for focusing the synthetic aperture image on the foreground object and an automatic method to compute the trimap and the alpha matte. The proposed algorithm is very efficient and has a per-pixel running time that is linear in the number of cameras. Our current system runs at several frames per second, and we believe that it is the first system capable of computing high-quality alpha mattes at near real-time rates without the use of active illumination or special backgrounds
Technology Area: Computer Vision
Modification Date: September 14, 2007