Fig. 3: Raman spectra of red pigments acquired from different areas.

a Raman spectrum acquired from points of A4, B6, E7, E8; b Raman spectrum acquired from points of A5, A7, B9, C8, D2, D9, E4; c Raman spectrum acquired from point of C3 and (d) Raman spectrum acquired from points of D6, D8 (All the point labels A-H are shown in Fig. 2, the legends below is the same).