One of my latest projects is a reproduction of "Head of a young girl"
by a Flemish painter Jacob van Oost I (1603-1671). As I was preparing the drafts, I noticed that the hair details in the back of the painting were almost invisible, while the hair on the face was much lighter in color.
That shows the dark oil paint he used for backgrounds affects the pigment of the upper layers, making pictures seem darker then when they were painted. To solve this predicament I used Krita to adjust the light and contrast ratio and uncover some of the details that were hidden in the background. The green pigment was completely absorbed / dissolved as you can clearly see on the flower petals and the leaves. The hair looks reddish in color as well because it`s green pigment faded away. Minute amount of white oil paint that was mixed in the hair strands kept its pigment and I was able to illuminate them and draw out the details.
Reproducing the painting as it is today would certainly make it recognizable, but I believe its intricate beauty should be restored as it was on the day it was painted. I started drawing out the outlines today, carefully filling in the hair and flower details so that after hundreds of years she can find her way back into the light.