Bare paint is matte: its rough surface scatters white light back at you. A clear varnish fills that surface, so the darks deepen and the colour saturates. That is why painters varnish. This piece computes the effect per pixel, from a published model of the film, and performs it: the varnish taken off, put back on, aged until it yellows, cleaned away again.

The yellow film is real, measured on another painting. This one has already been cleaned; the varnish on it now measures clear.

What is left over is the point. At the end the accent lights every pixel that no mixture of the eleven pigments documented for this painting can reach. The varnish had to be dealt with first: until it is, you cannot say what the paint itself is doing.