A novel algorithm for single image dehazing was proposed. Firstly，the color space is converted from RGB to HIS after the image normalization. The quadtree-segmentation is applied in hue component divided the image into elementary square units which had the same scene depth. The local airlight could be estimated from each square unit. To employ the characteristics of fog, the effects of fog on images are erased by using the optical model of foggy weather. Then the image of the restoration is obtained after the saturation component correction. The main advantage of this algorithm is reat time performance that is can be used in defogging both for color images and gray images. Compared with other algorithms, it is shown that this algorithm is able to restore foggy images effectively.