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煤矿综掘工作面复杂环境退化图像增强方法

Enhancement method of degraded images in complex environment of coal mine comprehensive excavation working face

  • 摘要: 为解决煤矿综掘工作面高尘雾与低照度环境因素导致的视觉成像退化问题,提出煤矿退化图像增强方法。首先,针对去雾过程中的环境光照估计难题,依据退化图像的RGB通道差与亮度−饱和度差异,构建退化图像的尘雾分布函数,结合最大类间方差法实现尘雾区域分割,并以尘雾分割图为引导,利用梯度域引导滤波实现对退化图像环境光照的自适应逐像素估计;其次,考虑退化图像的辉光效应缺陷,引入近光源系数并结合环境光照分布图来求取辉光项,从而通过辉光去除来对传统大气散射模型进行校正;再者,针对去雾过程中的透射率精准估计难题,引入亮通道先验来对原有的暗通道先验进行补充,以实现对退化图像暗亮区域的平滑过渡与自适应处理,并设计亮度感知权重结合高斯权值动态分配函数来对暗亮双通道透射率进行加权融合,最终利用校正后的大气散射模型实现对退化图像的反演去雾;紧接着,针对亮度校正过程中的局部过曝与颜色失真问题,基于反正切变换增强算法与自校准光照学习算法的互补特性,利用自适应伽马校正函数来提取2种算法的优化分量,并通过优化分量的加权融合实现对退化图像亮度的逐像素校正;最后,开展尘雾去除与亮度校正试验。试验结果表明:由尘雾去除试验的定性与定量分析可见,与DehazeNet、MSCNN、CEEF等算法相比,所提方法的去雾效果最佳,并且去雾后图像无结构性失真问题;DCP、CAP、DehazeNet、MSCNN与CEEF算法针对50组尘雾图像的平均尘雾去除率分别为49.9%、63.2%、62.2%、47.8%、74.5%,而所提方法的平均尘雾去除率高达83.5%。由亮度校正试验的定性与定量分析可见,与MSR、URetinex-Net、Retinex-Net等算法相比,所提方法对于亮度校正后图像的颜色保真度最高,并且无局部过曝问题;MSR、URetinex-Net、Retinex-Net、Zero-DCE与IceNet算法针对50组低照度图像的平均色度误差分别为55.9、54.8、53.0、32.3、14.3,而本研究所提方法的平均色度误差仅为7.7。该方法通过分析煤矿综掘工作面的复杂环境特征,实现了煤矿复杂环境退化图像增强,从而为煤矿人−机−环的智能感知提供技术支持。

     

    Abstract: To solve the problem of visual imaging degradation caused by the environmental factors of high dust and fog and low illumination in coal mine comprehensive excavation working face, the enhancement method for coal mine degraded images is proposed. Firstly, aiming at the problem of environmental illumination estimation in the dehazing process, the dust and fog distribution function of the degraded image is constructed according to the RGB channel difference and the lightness-saturation difference of the degraded image, and the dust and fog region is segmented by the maximum class variance method. Guided by the dust and fog segmentation map, the gradient domain guided filtering is used to realize the adaptive pixel-by-pixel estimation of the environmental illumination of the degraded image. Secondly, considering the glow effect defect of the degraded image, the glow term is obtained by introducing the near-light source coefficient and combining with the environmental light distribution map, so as to correct the traditional atmospheric scattering model by glow removal. Furthermore, in order to solve the problem of accurate transmission estimation in the dehazing process, the bright channel prior is introduced to supplement the original dark channel prior, so as to realize the smooth transition and adaptive processing of the dark and bright areas of the degraded image. The brightness perception weight combined with the Gaussian weight dynamic allocation function is designed to perform weighted fusion of dark and bright dual-channel transmission. The corrected atmospheric scattering model is used to realize the inversion dehazing of the degraded image. Then, in order to solve the problem of local over-exposure and color distortion in the process of brightness correction, based on the complementary characteristics of arc-tangent transformation enhancement algorithm and self-calibrated illumination learning algorithm, the optimized components of the two algorithms are extracted by adaptive gamma correction function, and the pixel-by-pixel brightness correction of the degraded image is realized by weighted fusion of the optimized components. Finally, the dust and fog removal and brightness correction experiments are carried out. The experimental results showed that, based on the qualitative and quantitative analysis of the dust and fog removal experiments, the proposed method has the best dehazing effect compared to algorithms such as DehazeNet, MSCNN, and CEEF, and there is no structural distortion in the dehazing images; the average dust and fog removal rates of DCP, CAP, DehazeNet, MSCNN, and CEEF algorithms for 50 sets of dust and fog images are 49.9%, 63.2%, 62.2%, 47.8%, and 74.5%, respectively, while the average dust and fog removal rate of the proposed method is as high as 83.5%. Based on the qualitative and quantitative analysis of brightness correction experiments, it can be seen that compared with algorithms such as MSR, URetinex Net, Retinex Net, etc., the proposed method has the highest color fidelity for brightness corrected images and there is no local overexposure problem; the mean chroma error of MSR, URetinex Net, Retinex Net, Zero DCE, and IceNet algorithms for 50 sets of low light images are 55.9, 54.8, 53.0, 32.3, and 14.3, respectively, while the mean chroma error of the proposed method is only 7.7. By analyzing the complex environmental characteristics of coal mine comprehensive excavation working face, the method realizes the enhancement of coal mine complex environmental degradation images, so as to provide technical support for the intelligent perception of coal mine personnel-equipment-environment.

     

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