P4NSU: Projection-Based Pretraining for Nonlinear Sparse Unmixing in Spectral Imaging

Area of Science:

• Spectral imaging analysis
• Deep learning applications
• Quantitative chemical analysis

Background:

• Nonlinear mixing effects in spectral imaging challenge accurate component quantification.
• Traditional model-specific algorithms have limitations in addressing these nonlinearities.
• Need for advanced methods to improve unmixing accuracy in hyperspectral and Raman imaging.

Purpose of the Study:

• To introduce P4NSU, a deep learning framework for projection-based pretraining of nonlinear sparse unmixing.
• To overcome limitations of traditional algorithms in spectral component quantification.
• To enhance accuracy and utility of spectral imaging analysis.

Main Methods:

• Developed P4NSU, a deep learning framework utilizing hierarchical pretraining and learnable projection.
• Hierarchical pretraining distills large spectral libraries into compact, task-specific subsets.
• Learnable projection maps spectra into a feature space simplifying unmixing to a linear problem.

Main Results:

• P4NSU consistently outperforms state-of-the-art linear and nonlinear methods on synthetic data, reducing RMSE by 14-51%.
• Achieved highest unmixing accuracy on real-world hyperspectral pigment imaging, reducing chalk RMSE by over 40%.
• Generated biochemically meaningful abundance maps for Raman imaging of leukemia cells, enhancing classification performance.

Conclusions:

• P4NSU provides a robust and practical solution for accurate quantitative analysis in spectral imaging.
• The framework demonstrates dual strengths in precise component quantification and effective information distillation.
• Open-source implementation facilitates advancement of spectral imaging analysis across diverse scientific fields.