Research On Single Image Defogging Algorithm Based On Dark Channel Prior Principle

The image acquired under fog conditions is seriously degraded. It suffers from poor contrast, low visibility and faint colors.This reduces the applications value of the image seriously. In almost every practical scenario the light reflected from a surface is scattered in the atmosphere before it reaches the camera. This is due to the presence of aerosols such as dust, mist, and fumes which will cause surface colors become faint and contrasts become reduced. It makes many troubles to People's industrial production and daily life. Many fields need defog algorithm, such as martial defense, target recognition, traffic navigation, remote sensing, satellite imaging. So the study on recovering a haze scene has a great significance.The dark channel prior is a statistics of the haze-free natural outdoor images.Using dark channel prior to estimate the thickness of the haze, recent research work has made significant progresses in single image defogging. However, it is difficult to apply existing method for processing high resolution input images because of the heavy computation costs of it. For some kinds of input images, existing method still can not reach enough accuracy which is required by visually-pleasing results.Motivated by this and based on thorough analysis of input image data, a kind of novel image prior, so-called gradient prior of transmission maps, has been proposed in this paper. Combining it with multiple-resolution image processing routine, we develop a powerful and practical single image defogging method. The experimental results show our gradient prior of transmission maps greatly reduces the computation costs of previous method. Furthermore, the optimization methods and parameter adjustment for our novel image prior enhance the accuracy of the computation related with transmission map, which results in better image quality under previous method's ill-situation. Overall, compared with the state of the art, our new single image defogging method achieves the same even better image quality with only around 1/8 computation time and memory cost.