A unified approach to bad pixel removal and adaptive CFA demosaicking

The fabrication process for today´s digital cameras will inevitably produce some defective pixels in those mega-pixel image sensors. In the manufacturing process, these defective pixels, known as bad pixels, will normally be mapped out. However, more bad pixels could appear over time with camera usage, and some would only appear on a long exposure and/or at high ISO settings. It is therefore not desirable to permanently map out those bad pixels as they can still function at normal settings. As those bad pixels will interfere with the demosaicking process, in this paper, we propose an adaptive method to avoid inclusion of those bad pixels in the interpolation process. This is achieved by adaptively varying the order of interpolation so that the length of interpolation is shorter if a bad pixel is located closer to the pixel being interpolated. The bad pixels are located by using a median-based multi-shell filter structure. It has been shown that our proposed method outperforms other existing bad pixel correction techniques.