A method and terminal for image defogging

Abstract

The invention discloses a method and a terminal for defogging an image, which acquires the top layer image of a Gaussian pyramid of an image to be processed; judges whether defogging is needed according to the fog concentration of the top layer image of the Gaussian pyramid, and can avoid further defogging processing on the fog-free image; Calculate the atmospheric light value and transmittance for the top image of the Gaussian pyramid that needs to be defogged, and if there is a sky area, correct the transmittance of the sky area, and perform guided filtering on the transmittance, then remove the haze for the top image of the Gaussian pyramid, and set The image after dehazing is restored to the original resolution; among them, by dehazing the top image of the Gaussian pyramid and then restoring the dehazed image to the original resolution through upsampling, the image detail loss can be reduced while improving the dehazing efficiency , and correct the perspective ratio of the sky area of ​​the image, which can avoid the overexposure of the sky area after defogging, and greatly reduce the color distortion of the sky area.

Description

technical field [0001] The invention relates to the field of image processing, in particular to an image defogging method and terminal. Background technique [0002] One method of image defogging in the prior art is the dark channel prior theory proposed by observing and counting a large number of outdoor natural fog-free images. Combining the dark channel prior theory with the atmospheric light scattering model, the image can be realized to fog. However, this algorithm has the following defects: first, the calculation efficiency is very low, and it cannot be applied to the industrial world; second, the dark channel prior knowledge is not valid for the sky area, and the sky area has serious color distortion after fog removal; third, the atmospheric light estimation method It is too simple, and the defogged image is often overexposed or too dark due to incorrect calculation of atmospheric light values. [0003] Another method is to replace the soft matting method with low c...

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Problems solved by technology

However, this algorithm has the following defects: first, the calculation efficiency is very low, and it cannot be applied in the industry; second, the dark channel prior knowledge is not valid for the sky area, and the sky area has serious color distortion after dehazing; third, the atmospheric light estimation method It is too simple, and the defogged image is often overexposed or too dark due to incorrect calculation of atmospheric light values

[0003] Another method is to replace the soft matting method with low computational efficiency with guided filtering, which greatly improves the computational efficiency, but for large-resolution images, the computational speed of this method is still relatively slow

[0004] Another method is to use quadtree search to calculate the atmospheric light value, which improves the accuracy of atmospheric light value calculation, but the problem of low calculation efficiency has not been solved

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