Study On The Restoration Of Foggy Image Based On Dark Channel Prior

Under foggy weather conditions, the image contrast decrease and the image details can not recognize due to the outdoor scenes which are affected by the fog. Consequently the information of image scene become blurred which make great difficulties for the subsequent image processing and analysis. Therefore, studying the image restoration technology under the foggy weather conditions to increase the contrast and sharpness of the image, and to improve the quality of the image, has important theoretical and practical values to ensure that the computer vision system can also work in a reliable, stable state in inclement weather.On the research of foggy image restoration technology, there are two methods. One is processing from the perspective of the image enhancement. The other one is processing the fog image based on physical imaging model. Although the image enhancement method can improve the visual effect to a certain extent, but usually can not remove the influence of fog effectively. In contrast, the method based on imaging model has better results and universality due to the clear physical interpretation. There are a lot of methods based on physical imaging model at present. Among them, the image defogging method based on the atmospheric scattering model and Dark Channel Prior colors work effectively. However, the method still has some disadvantages. This paper presents an image defogging improved algorithm based on Dark Channel Prior to improve the defogging algorithm based on Dark Channel Prior for these deficiencies.Therefore, this paper formulates with the restoration of foggy image program, designs and implement corresponding algorithm through the research on the foggy image degradation mechanism and the analysis of the foggy image degradation model which is atmospheric scattering model. For the problem to the defogging algorithm of dark channel prior, the paper convert the image from the RGB color space to the YUV color space to process, to maintain the authenticity of the color. In order to reduce the computation time, the guided filter is used to correct the transmission rate. The time is greatly shortened. For the problem of image brightness favoring dark after defogging, this paper proposes a new adaptive method of image brightness adjustment to get the best visual effects. Experiments show that the improved algorithm can effectively remove the impact of the fog, enhance the contrast of image and increase the visibility of image, The method is a fast and effective algorithm of digital image defogging.