FPGA-based real-time Bayer demosaicking algorithm and its implementation

The Bayer array is widely applied in the front-end sensors such as complementary metal oxide semiconductor/charge-coupled device (CMOS/CCD), in order to compress and encode the color images. The Bayer array is restored to red, green and blue color arrays by demosaicking algorithm, and the performance of the algorithm affects the imaging effective resolution and texture details. With the development of semiconductor technology and proposal of demand of new applications such as target recognition, the image devices move toward high resolution and low latency, and the original demosaicking algorithm encounters performance bottlenecks. A real-time demosaicking algorithm based on the field programmable gate array (FPGA) was proposed, which could accurately extract the local gradient direction of the image and guide the interpolation restoration of the color. The overall algorithm only needed 7 lines of data delay, and fully considered the hardware characteristics of FPGA, and designed the modules such as line buffer, gradient operator and gradient direction interpolation to reduce the hardware cost. The experimental results show that the algorithm can achieve the micron-level latency, and maintain the restoration effect of texture detail area of the image. The average peak signal to noise ratio (PSNR) on Kodak data set can reach to 38.26 dB.