Perception of works Palaeolithic rock art, and sculptures in particular, varies greatly depending on lighting, scale and the angles from which they are photographed. This is why it is critical to vary these factors when photographing the walls.
Photographs of sculptures and engravings are taken by placing the camera parallel to the mean plane of the wall to limit the effects of convergence of horizontal and vertical lines. The images are then corrected using a computer application to adjust for geometric distortions caused by the lens.
Modern sources of light (cold light spotlights, flash) cannot factor in the Palaeolithic lighting of the sculptures: sunlight is excluded, as three of the four sites studied have been darkened for conservation reasons, as well as hearths, which have been found and reported at the base of the wall in every one of these shelters. 3D modelling, however, allows researchers to simulate light sources and thus fill in some of these gaps.
At Roc-aux-Sorciers and Cap Blanc, traces of painting found on wall elements can be seen in photographs taken under white light and then given colorimetric treatment by computer.