SFEDet: edge-guided spatial-frequency fusion network for steel surface defect detection
摘要
Steel surface defect detection remains challenging due to low-contrast textures, fine crack-like patterns, and weakly textured granular defects, particularly under uneven illumination. This paper presents SFEDet, an improved detector built upon YOLO12 with three tailored designs. First, Learnable Gray Preparation (LGP) performs learnable contrast enhancement at the input stage via a gated residual formulation. Second, DefectFreqFusion replaces conventional concatenation with spatial–frequency dual-path fusion for robust multi-scale feature integration. Third, an edge- and morphology-aware neck enhancement scheme is developed, combining C2fDE for multi-scale receptive fields, Edge-Guided Attention Module (EGAM) for Sobel edge-guided attention, and Efficient Head Preparation (EfficientHeadPre) for lightweight pre-detection refinement; together these modules constitute the Bottom-Up Steel Neck (BU-SN). Experiments on NEU-DET (640