Abstract: Aiming at solving the difficulties in night-time edge detection of guideline during the autopilot navigation of rubber tyred gantry (RTG), a color weighted guided image filtering-Retinex (CWGIF-Retinex) algorithm is proposed. Firstly, the weight estimation of weighted guided image filtering is improved by using vector gradient method. And the edges of color images processed by Retinex are extracted as weights. Secondly, the illuminance components of guideline image are estimated by using CWGIF algorithm. And then, the reflection components are calculated by using the single-scale Retinex algorithm. Finally, an image with enhanced colors and edges is obtained. The results of experiments indicate that CWGIF-Retinex algorithm compared with traditional algorithms can enhance the colors of low illumination area while achieving the goals of removing halo effect, color fidelity, and enhancing the contrast of guideline edges.

Key words: color weighted guided image filtering(CWGIF) algorithm; Retinex algorithm; night image; color enhancement; autopilot navigation; rubber tyred gantry (RTG) navigation