Virtual light: digitally-generated lighting for video conferencing applications

In this paper we discuss a simple method to improve the lighting conditions of a scene or video sequence. We focus on modifying the intensities of existing light sources and on inserting additional virtual lights into a scene. We target video conferencing applications where typical lighting conditions (i e the average office or home environment) are poor. Our model is much simpler and is a departure from approaches such as re-lighting, developed in computer-augmented reality (CAR) where the scene is first reconstructed geometrically by means of computer vision techniques We rely on a well-known illumination equation that takes into account light attenuation, plus lambertian and specular reflection Our first scenario models a 3D space in which the image or video frame lies on a 2D plane. Virtual lights are placed in the 3D space and illuminate the 2D image We then propose a refined model for talking head video sequences where the talking head is detected, tracked and its surface is modeled with a 3D ellipsoid. Results show that convincing lighting improvements can be achieved in both scenarios