Fig. 3
From: A multi-analytical study of the palette of impressionist and post-impressionist Puerto Rican artists
Registered RGB, RIS distribution maps and associated reflectance curves for each identified endmember (EM) in CAM-1329. RIS distribution maps suggest the use of an ochre-based retouching (EM1); ultramarine blue (EM2); green pigment mixtures containing ultramarine blue (EM3, EM4 and EM5); vermilion and ochre mixture (EM6); a possibly Emerald/Scheele’s green pigment (EM7); and unknown yellow pigments (EM8 and EM9). Sharp bands at 437, 543, and 610 nm (marked with an asterisk) are associated with light pollution from nearby ambient lightning. Threshold and minimum distance values of respectively 0.1 and 15 were used for the RIS endmembers extraction procedure