Fig. 17

a Comparison of spectra of the transparent area inside the stained glass, taken from all the acquisitions of AG-1177. Each spectrum is an average signal obtained by selecting the entire transparent area (Fig. 8b and e). The red and green lines refer to the spectra obtained when the transmittance reference is taken inside the stained glass, which appear flat due to the division occurring during the image processing phase. The characteristic bands of the transparent glass can be observed when the reference is taken from the windows’ panes. b–d Comparison of spectra of yellow, blue, and green glass on the right side of the panel, taken from all the acquisitions. The red and green lines refer to the spectra obtained when the transmittance reference is taken inside the stained glass and appear slightly different from the others due to effects related to the radiometric correction. Figure 6 shows the points where the spectra of colored glass were taken