4. Depth Map Denoising via CDT-Based Joint Bilateral Filter

Bi-modal image processing can be defined as a series of steps taken to enhance a target image with a guidance image. This is done by using exploitable information derived from acquiring two images of the same scene with different image modalities. However, while the potential benefit of bi-modal image processing may be significant, there is an inherent risk; if noise or defects in the guidance image are allowed to transfer to the target image, the target image could become corrupted rather than improved. In this chapter, we present a new method to enhance a noisy depth map from its color information via the joint bilateral filter (JBF) based on common distance transform (CDT). This method is composed of two main steps: CDT map generation and CDT-based JBF. In the first step, a CDT map is generated that represents the degree of pixel-modal similarity between a depth pixel and its corresponding color pixel. Then, based on the CDT map, JBF is carried out in order to enhance depth information with the aid of color information. Experimental results show that CDT-based JBF outperforms other conventional methods objectively and subjectively in terms of noise reduction, as well as inherent visual artifacts suppression.