In order to solve the problems that fog haze weather vehicle auxiliary safety system image sensor has low contrast and color distortion, an image enhancement method is proposed based on the improved dark channel prior theory. The image atmosphere intensity value estimation method is improved using interval sampling, removing brightness mutations area. And the transmittance calculating is optimized through region separating. Experimental results show that the proposed algorithm has better performance than other algorithms in real-time, color fidelity and picture contrast ratio.