An Effective Directional Demosaicing Algorithm Based On Multiscale Gradients

In a typical digital camera, the colors of the scene are captured by a single CCD or CMOS sensor array, where for each pixel the sensor detects a particular color channel. This kind of sensor is called Color Filter Array. The remaining two color channel values need to be estimated to obtain a complete color image. This technique is called demosaicing or Color Filter Array interpolation. This project proposes a directional approach to the CFA interpolation problem that makes use of multi scale color gradients. The relationship between color gradients on different scales is used to generate signals in vertical and horizontal directions. It proposes a demosaicing method that uses multi scale color gradients to adaptively combine color difference estimates from various directions. Then determine how much each direction should contribute to the green channel interpolation based on these signals. Finally Structural approximation algorithm is used to refine red and blue channel.so the quality of the image is to be improved. This type of approach requires a limited computational cost and gives good performance even when compared to more demanding techniques. The proposed method is easy to implement since it is noniterative and threshold free. Experiments on test images show that it offers superior objective and subjective interpolation quality.