Fig. 4
From: Improved spectral imaging microscopy for cultural heritage through oblique illumination
Cross-section of the multi-layered mockup sample including the reconstructed RGB image and the corresponding pigment maps created by sparse modeling of the diffuse spectral dataset. The maps were created using an orthogonal matching pursuit (OMP) algorithm with a dictionary comprised of pure pigment spectra (ultramarine, cadmium yellow, vermillion, madder lake, zinc white, and Prussian blue). Distribution weights are normalized between 0 and 1 on a per pixel basis