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Zhang et al. J Mater Inf 2024;4:34 https://dx.doi.org/10.20517/jmi.2024.64 Page 17 of 28

Figure 13. The weld seam thickness prediction only based on welding parameters. (A) Raw data; (B) data after screening to exclude
obvious offset.

Figure 14. The correlation between voltage and arc length. (A) Welding voltage changes over time; (B) arc length varies with time.

Secondly, the original molten pool image size obtained by the information acquisition and processing
system is 1,280 × 1,024. The exceptionally high local temperature of the molten pool generates intense
thermal radiation, leading to a predominantly black background in the molten pool images. Nevertheless,
the background area contains minimal information relevant to welding quality. To reduce redundancy and
improve image processing efficiency, the image is cropped to extract the ROI corresponding to the molten
pool. As depicted in Figure 16, considering possible camera motion during the process, the cropping
window size is set to 500 × 500, ensuring that the image captures only the molten pool region.

Thirdly, to further improve the visual effect of the arc image and achieve arc feature extraction, image
enhancement technology is introduced. The original welding arc image, as shown in Figure 17A, lacks
sufficient contrast for effective arc contour extraction. As shown in Figure 17B, adaptive histogram
equalization is an improvement on histogram equalization, which not only effectively enhances the local
contrast of the image but also avoids excessive contrast enhancement. In the case of different lighting