Training dataset for spectral compressive imaging in DL4sSR

Training dataset should be placed as \DL4sSR\3SCI\26train_256_enhanced.h5

Benchmark: https://github.com/JiangHe96/DL4sSR

Reference: J. He, Q. Yuan, J. Li, Y. Xiao, D. Liu, H. Shen, and L. Zhang, "Spectral super-resolution meets deep learning: achievements and challenges," Information Fusion, 2023.