The Study Of Automatic White Balance Complementary Algorithm And Fpga Verification

Human visual system has the characteristic of color constancy, so the image that the human eye recepts will not be affected by the light source. CMOS image sensor’s work mimics human visual system, but it doesn’t have the color constancy characteristic, so the automatic white balance function is necessary for the image sensor to eliminate the impact of the light source.This thesis presents the design and implementation of a novel automatic white balance module (AWB) in the CMOS image sensors for digital pre-processing circuit. Because it is the design of single chip system, it is required that the circuit is small in scale, low resource consuming, low power consuming and easy to transplant. Taking into account the complexity of implement and the effect of disposition, it developed a kind of method combined gray world with perfect reflector to modify the color. Combining the two algorithms to expand the scope in point, it makes up the shortage of them to a certain extent. In addition, we use color temperature curve to exclude monochrome scenes, avoiding the white balance failure caused by a large monochrome area. In order to measure the adjustment effect of the algorithm better, we use the tone average of image as a evaluation criterion. The algorithm of the thesis is based on the matlab simulation, and we take some comparison experiments with the other two algorithms by testing in different color temperature environments and monochromatic scenes to verify the proposed algorithm has better correction effect of the color cast. In this thesis, modules are designed by Verilog hardware description language, and then we accomplish the implementation and verification on FPGA.