Abstract: The basic principle of the homomorphic filter is introduced. A homomorphic filter model and parameter expression was established by using Matlab. On this basis, the homomorphic filtering method was applied to the brightness of color image and image contrast enhancement. It is shown that the method performs well in enhancing the local contrast of an image while maintaining its global appearance, and the expected filter effect is achieved. Experiments prove that the method is suitable for human visual observation to conduct image analysis and judge.