Range-enhanced active foreground extraction

We describe a new technique that uses active scene illumination to perform foreground-background segmentation and recover partial HDR information. We explore the fact that relative tones can be recovered by varying illumination intensity, without knowing the camera response function. In our approach, the scene is illuminated with an uncalibrated projector and two images of the scene are captured under different illumination conditions. By taking advantage of the fact that the projector can be set up to illuminate only the foreground, we are able to distinguish the foreground from the background. The output of our system is a segmentation mask, together with a image with additional tonal information for the foreground pixels. As an application, we show how to produce spatially variant tone mapped images, where background and foreground receive different treatments. The segmentation and the visualization algorithms are implemented in real-time, and can be used to produce range-enhanced video sequences.