Rainbow Flash Camera: Depth Edge Extraction Using Complementary Colors

Abstract

We present a novel color multiplexing method for extracting depth edges in a scene. It has been shown that casting shadows from different light positions provides a simple yet robust cue for extracting depth edges. Instead of flashing a single light source at a time as in conventional methods, our method flashes all light sources simultaneously to reduce the number of captured images. We use a ring light source around a camera and arrange colors on the ring such that the colors form a hue circle. Because complementary colors are arranged at any position and its antipole on the ring, shadow regions where a half of the hue circle is occluded are colorized according to the orientations of depth edges, while non-shadow regions where all the hues are mixed have a neutral color in the captured image. In an ideal situation, the colored shadows in a single image directly provide depth edges and their orientations. In practice, we present a robust depth edge extraction algorithm using an additional image captured by rotating the hue circle with 180°. We demonstrate the advantages of our approach using a camera prototype consisting of a standard camera and 8 color LEDs.