Ophelia under infra-red
Ophelia under infra-red

Many paint pigments are more transparent to infra red radiation than to visible light. The greater transparency of the paint enables us to see any drawings under the paint. We cannot see this with our naked eyes. A photograph needs to be taken and processed for us to see the results of this type of examination. In this picture of Ophelia, we can see a slight shift in the position of the weeping willow.