An enhancement method of fog-degraded images

Images are often significantly degraded by fog and their values are greatly reduced. According to retinex theory and the properties of fogged images, fog degradation can be eliminated by modifying illumination variation. The multi-scale retinex (MSR) algorithm was analyzed and an enhancement method directing to fogged images was proposed. Firstly, a preliminary global luminance was adjusted by linear stretching and screen algorithm to increase the luminance of darker pixels and compress the dynamic range as well. Then the local contrast was increased by an improved algorithm based on MSR. Finally, the output of local contrast enhancement was processed by the normal clipping stretching to realize color correction. Experiments show that the algorithm can effectively remove fog degradation from color images.