Development and Implementation of Automatic White Balance Based on Luminance Compensation

Automatic white balance plays a key role in image signal processing circuit of image sensors, and determines image quality to a large extent. An automatic white balance algorithm based on luminance compensation is proposed. The algorithm establish the equations of RGB channels between the captured image and the natural one firstly based on the assumption that the luminance average of the whole image holds the line when the light source has changed. Then, to compensate the loss of luminance that might be made by the primary plus and make the corrected image equal to the natural one, the algorithm further combines the max white method to amend the gains. So the image will be proofread accurately. To evaluate the proposed algorithm, the subjective observation method and the objective comparison method are both used, and the results of the test prove that the corrected results of image emendated by it are excelled to that by some traditional algorithms. Finally, this algorithm is implemented with VLSI design, and the test of integration indicates that the algorithm is easy to be realized in the integrated circuit and can satisfy the requirement of real-time processing.