The stability of arc bubble is a crucial indicator of underwater wet welding process. However
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limited research exists on detecting arc bubble edges in such environments
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and traditional algorithms often produce blurry and discontinuous results. To address these challenges
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we propose a novel arc bubble edge detection method based on deep transfer learning for processing underwater wet welding images. The proposed method integrates two training stages: pre-training and fine-tuning. In the pre-training stage
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a large source domain dataset is used to train VGG16 as a feature extractor. In the fine-tuning stage
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we introduce the Attention-Scale-Semantics (ASS) model
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which consists of a Convolutional Block Attention Module (CBAM)
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a Scale Fusion Module (SCM) and a Semantic Fusion Module (SEM). The ASS model is further trained on a small target domain dataset specific to underwater wet welding to fine-tune the model parameters. The CBAM can adaptively weight the feature maps
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focusing on more crucial features to better capture edge information. The SCM training method maximizes feature utilization and simplifies training by combining multi-scale features. Additionally
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the skip structure of SEM effectively mitigates semantic loss in the high-level network
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enhancing the accuracy of edge detection. On the BSDS500 dataset and a self-constructed underwater wet welding dataset
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the ASS model was evaluated against conventional edge detection models—Richer Convolutional Features (RCF)
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Fully Convolutional Network (FCN)
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and UNet—as well as state-of-the-art models LDC and TEED. In terms of Mean Absolute Error (MAE)
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accuracy
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and other evaluation metrics
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the ASS model consistently outperforms these models
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demonstrating edge detection capabilities that are both effective and stable in detecting arc bubble edges in underwater wet welding images.