Table 4.

Classification results of the PCA-BP model for natural weld defects under alternating magnetic field excitation.

Defect Types	Number of Images	Train Samples	Test Samples	Recognition Result	Classification Accuracy/%
Crack	250	200	50	48	96
Pit	250	200	50	46	92
Lack of penetration	250	200	50	45	90
Gas pore	250	200	50	39	78
No defects	250	200	50	49	98
Total	1250	1000	250	227	90.8