Accurate depth map estimation is widely used in many computer vision applications including object detection, human pose analysis, and semantic scene recognition. Many depth acquisition systems have been developed. A common issue among those system is the limited resolution of the acquired depth map. In this project, we propose a simple and effective technique to enhance the resolution using the idea of  "residual interpolation".

Residual interpolation performs upsampling in the residual domain, where the residual is defined as the difference between the tentatively estimated high-resolution image and the input low-resolution image intensity. Residual interpolation adds the interpolated residual to the tentative estimate to enhance the upsampling result.

Motivation

In general, the interpolation accuracy depends heavily on the input image smoothness. This is a common property for any kind of interpolation algorithms. In other words, the low gradient energy of the input image makes interpolation easy. That observation implies that one can improve the interpolation performance further if the input image could be transformed into the domain with the lower gradient energy. Residual interpolation has been proposed based on this idea.