Abstract: In order to improve the performance of image enhancement under different illumination conditions, an effective image enhancement method is proposed, which is based on the improved histogram equalization and Retinex algorithm. First, the low frequency components of the image are obtained using the ideal low-pass filter and its dynamic range is optimized by the improved histogram equalization. Second, the high frequency components of the image are estimated by the guided image filtering, which replaces the Gaussian filter in Retinex algorithm. Finally, the estimated results are amplified by the linear processing method. Experimental results show that the performance of the proposed method is better than the traditional Retinex algorithm and improved histogram equalization algorithm by the subjective and objective evaluation. Furthermore, the proposed method effectively improves the image’s visual effects and intelligibility with strong robustness.

Key words: image processing; image enhancement; histogram equalization; retinex algorithm; guided image filtering