Structural Preservation Governs Data Augmentation in Deep Learning-Based Laser Speckle Material Classification
Standard data augmentation techniques exhibit limited efficacy in laser speckle-based material classification because they overlook the structural statistical properties inherent to speckle patterns, which arise from coherent interference. This work proposes a parameterized augmentation framework to systematically evaluate the impact of various perturbations—including rotation, Gaussian blur, independent noise, spatially correlated speckle-aware noise, intensity jitter, and spatial masking—on classification performance. Leveraging ResNet18 and EfficientNet-B0 models alongside ordinary least squares analysis, the study demonstrates that augmentation effectiveness hinges on preserving the spatial and frequency-domain structure of speckle rather than the magnitude of perturbation. Structure-preserving augmentations, such as spatially correlated noise, substantially enhance robustness, whereas Gaussian blur and independent noise degrade performance. The proposed framework accounts for up to 87.9% of performance variance, establishing a design principle centered on physically informed, structure-preserving augmentation.