Fig. 7
![Fig. 7](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs40494-019-0258-x/MediaObjects/40494_2019_258_Fig7_HTML.png)
a Detail of sample G3 investigated with PL microscopy. b Reconstructed spectra in selected ROIs of the Layer 3 and Layer 5 (the two white), identified as zinc white pigment with traces of titanium white in Layer 3. c False colour images: nanosecond timescale gated image (370–390 nm) and microsecond timescale gated image (BP450/40 on the left, BP750/40 on the right)