Artists sometimes change or improve paintings by painting over old versions. Through careful examination or special imaging, we can sometimes see these ghosts of lost art again.
Historically, artists very commonly altered the composition of paintings as they were painting them, or changed them well after they were first “finished.” Some artists prepared a simple drawing on the canvas before they began applying paint (so-called underdrawing) and the finished painting differed from the underdrawing. In any of these cases, the earlier version of the painting is mostly invisible. But not always, and especially not now.
Look at the picture above. It’s a close-up detail from Picasso’s famous Blue Period painting The Old Guitarist, but there’s a spectral ghost of an old woman peering at us. It’s actually one of three hidden figures in the painting, perhaps two previous paintings on the same canvas that preceded the guitarist figure. X-ray and infra-red analysis has revealed more details from these lost paintings, and researchers have used machine learning to reconstruct what they may have looked like. See the link “Raiders of the Lost Art” below for details.
The term used for these shadows of old art is pentimento – “repentance.”