Fig. 9

Comparison of spectra obtained on the left and right side from the pair of datacubes processed using the same glass pane as reference for the three selected colors (yellow, green, and blue). The width of the band in the NIR region associated to Fe²⁺ is indicated. The peak at 750 nm is an artifact probably due to the sunlight spectrum or interference from atmosphere. Notice how the band of Fe²⁺ tends to disappear when the radiometric correction is performed using a transparent area inside the stained-glass panel as reference. Figure 6 shows the points where the spectra were taken