Fig. 6
From: Visualising varnish removal for conservation of paintings by fluorescence lifetime imaging (FLIM)
Natural resin varnish samples. A dammar and B mastic resin-based varnish samples following ambient ageing (Amb., top row) and accelerated ageing (Acc., bottom row) are displayed. Each row contains images of (i) intensity-weighted fluorescence lifetime fractional contributions, (ii) UV-excited broadband fluorescence intensity, and (iii) visible-light illumination photographs. The ranges of the fractional contributions and the false-colour scales are below each fractional contribution image. The characteristic global fluorescence lifetimes are in the top-right corners. A The visible rectangles are the consequence of historical varnish removal treatment. (i) Elliptical rings visible in the top-right quadrant result from the inhomogeneous illumination, which influences only the grey-scale intensity weighting and not the colour-scale fluorescence lifetime fractional contributions. (i, ii) Visible streaks are caused by variable varnish layer thickness due to its application by brush. Scale bar 5 mm