According to the effect of fog from images

a new method for enhancing images taken in fogs is proposed in this paper. It dose not need atmospheric model and just performs on the image

directly enhancing details of the scene in the image. A moving mask is adopted to segment scene at different depth

then each pixel in the mask is processed using block-overlapped histogram equalization. At the same time the influence of mask's size also is discussed in this paper. Though the enhance operation will improve visual result

it also will bring noise amplification in sky region. To restrain the adverse effect

the sky region should firstly be segmented before enhance operate. Using optimal normal distribution to approach the characteristic of image gray distribution

then by the estimated distribution

the range of pixel value in the sky region can be got. By the information

the sky region can be segmented from the image. Experiments show that this algorithm can efficiently improve the degradation of image and enhance the clearness of image.