An enhancement method for low light images in coal mines
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摘要: 煤矿井下照明有限,并且具有大量粉尘、雾气,使得采集到的图像对比度低、光照不均、细节信息弱,并含有大量噪声。基于传统模型的图像增强方法鲁棒性较差,常会引起图像过度增强和色彩失真;基于深度学习的图像增强方法大多没有考虑增强引起的噪声放大。针对上述问题,提出了一种面向煤矿井下低光照图像的增强方法。采用卷积神经网络构建图像增强网络,该网络包括特征提取模块、增强模块和融合模块。特征提取模块对输入图像进行不同程度的卷积,提取多层次的图像特征,得到多个特征层;增强模块对提取到的特征层通过子网络进行增强,强化不同程度的细节特征;融合模块将增强后的特征层进行融合,输出增强图像。之后通过结构损失函数、内容损失函数和区域损失函数的约束,提高图像质量并有效抑制图像颜色失真与噪声放大,得到最终的增强图像。实验结果表明,该方法能够有效提升煤矿井下低光照图像的亮度和对比度,并且具有较强的噪声抑制能力,使图像能更好地恢复原有的细节信息,同时避免出现过曝光或颜色失真。Abstract: Underground lighting in coal mines is limited. There is a large amount of dust and mist, resulting in low contrast, uneven lighting, weak detail information, and a large amount of noise in the collected images. The image enhancement methods based on traditional models have poor robustness, often causing excessive image enhancement and color distortion. Most image enhancement methods based on deep learning do not consider the noise amplification caused by enhancement. In order to solve the above problems, an enhancement method for low light images in coal mines is proposed. The image enhancement network is constructed by using convolutional neural networks. The network includes feature extraction modules, enhancement modules, and fusion modules. The feature extraction module convolves the input image to varying degrees, extracts multi-level image features, and obtains multiple feature layers. The enhancement module enhances the extracted feature layers through sub-networks to enhance different levels of detail features. The fusion module fuses the enhanced feature layers and outputs enhanced images. Then, through the constraints of the structure loss function, content loss function and area loss function, the image quality is improved. The image color distortion and noise amplification are effectively suppressed to obtain the final enhanced image. The experimental results show that this method can effectively improve the brightness and contrast of low light images in coal mines. The method has strong noise suppression capability, enabling the image to better restore the original details while avoiding overexposure or color distortion.
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Key words:
- low light images of coal mines /
- image enhancement /
- image denoising /
- deep learning /
- loss function
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表 1 本文方法下图像增强客观评价结果
Table 1. Objective evaluation results of image enhancement of the proposed method
图像编号 PSNR SSIM 原始图像 增强图像 原始图像 增强图像 T112 13.54 21.89 0.43 0.78 T118 14.55 18.65 0.13 0.74 T120 12.19 21.21 0.30 0.73 表 2 EM添加Concat层前后NIQE值对比
Table 2. Comparison of NIQE value before and after enhancement module adding Concat layer
图像编号 NIQE 无Concat层 添加Concat层 T801 2.41 2.35 T822 3.78 3.59 T828 4.49 4.24 T841 2.83 2.58 平均值 3.38 3.19 -
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