An edge-directed demosaicing algorithm based on integrated gradient

In this paper, an efficient edge-directed demosaicing algorithm for Bayer images is presented. A new edge-sensing measure called integrated gradient (IG) is exploited to extract gradient information in both color intensity and color difference domains simultaneously for the interpolations. This measure supports full resolution and allows one to interpolate the missing samples along an appropriate direction. By sharing it in different stages, it guarantees consistency of the interpolation direction in different channels and saves the effort required to repeatedly extracting gradient information from intermediate interpolation results. An IG-based green plane enhancement is also proposed to further improve the method's efficiency. Simulation results confirmed that the proposed demosaicing algorithm outperforms most up-to-date demosaicing algorithms in terms of both quality and complexity.

I. INTRODUCTION

To reduce cost, most digital cameras acquire color scenes with a single image sensor. Over the sensor, the Bayer color filter array (CFA) [1] as shown in Fig. 1 is coated to record one of the three primary colors at each pixel. A process called color demosaicing is then carried out to convert the mosaic Bayer images to full color images. This process is critical as it determines the camera output image quality. Fig. 1 Four Bayer regions with their center pixels having (a)-(b) green, (c) red and (d) blue Bayer samples respectively