Enhanced real-time stereo using bilateral filtering

In recent years, there have been significant strides in increasing quality of range from stereo using global techniques such as energy minimization. These methods cannot yet achieve real-time performance. However, the need to improve range quality for real-time applications persists. All real-time stereo implementations rely on a simple correlation step which employs some local similarity metric between the left and right image. Typically, the correlation takes place on an image pair modified in some way to compensate for photometric variations between the left and right cameras. Improvements and modifications to such algorithms tend to fall into one of two broad categories: those which address the correlation step itself (e.g., shiftable windows, adaptive windows) and those which address the preprocessing of input imagery (e.g. band-pass filtering, Rank, Census). Our efforts lie in the latter area. We present in this paper a modification of the standard band-pass filtering technique used by many SSD- and SAD-based correlation algorithms. By using the bilateral filter of Tomasi and Manduchi (1998), we minimize blurring at the filtering stage. We show that in conjunction with SAD correlation, our new method improves stereo quality at range discontinuities while maintaining real-time performance.