An illuminance improvement and details enhancement method on coal mine low-light images based on Transformer and adaptive feature fusion

High quality mine images can provide guarantee for mine safety production, and improve the performance of subsequent image analysis technologies. Affected by low illuminance environment, mine images suffer low brightness, uneven brightness, color distortion, and serious loss of details. Aiming at the above problems, an illuminance improvement and details enhancement method on coal mine low-light images based on Transformer and adaptive feature fusion was proposed to enhance the brightness and detail of mine low illuminance images. Based on the idea of generative confrontation, a framework of generative adversary agent model was built, and the target image domain was used instead of a single reference image to drive discriminator to supervise the training of generator, so as to achieve adaptive enhancement of low illuminance images; The feature encoder was built based on the feature representation learning theory to decouple the image into illuminance component and reflection component, the method can avoid the interaction between illuminance and color features during image enhancement to solve the color distortion; the CEM-Transformer Encoder was designed to enhance the brightness component, the method can improve the overall image brightness and eliminate the local area brightness unevenness, by capturing the global context and extracting the local area features; In the process of reflection component enhancement, the skip connection combined with CEM-Cross-Transformer Encoder was used to adaptively fuse low-level features with features at the deep CNN layers, which can effectively avoid the loss of detailed features, and ECA-Net was added to the encode network to improve the feature extraction efficiency of the shallow CNN layers. The low illuminance mine image dataset was produced to provide data resources for the low illuminance mine image enhancement task. The experiments show that, compared with five advanced low illuminance image enhancement algorithms, the quality indicators PSNR, SSIM and VIF of the images enhanced by the algorithm are improved by 16.564%, 10.998%, 16.226% and 14.438%, 10.888% and 14.948% on average on the low illuminance mine image dataset and the public dataset. And the algorithm also perform well in subjective visual evaluation. The above results prove that the algorithm can effectively improve the overall image brightness and eliminate the uneven brightness, thus to achieve mine low illuminace image enhancement.