A real-time auto white balance algorithm for mobile phone cameras

Auto white balance (AWB), a critical component of the image pipeline in digital cameras, is responsible for producing accurate color by automatically removing the undersired color cast introduced by the illumination. AWB estimates the scene illumination by processing the digital values of the pixels in the captured image; therefore, objects colors in the scene are often confused with the color of the light source, leading to wrong color cast in white balanced images. In this paper, we propose a color histogram based AWB algorithm that is capable of producing accurate color in the presence of dominant object colors. Our approach is based on a statistical estimation of the probabilities of colors in natural scenes under different illuminations. These statistics can be easily collected during the AWB calibration phase using standard equipment. The proposed AWB algorithm is computationally efficient and runs real-time in a mobile phone camera.