IR reflectography is used by conservators and art-historians before the restoration work, and during any documentation phase .

IR reflectography is an a unobtrusive technique, which makes it specially suitable for the investigation of artworks.

It generally makes underdrawing and underpainting visible. (An Underdrawing is the preparatory sketch that precedes the application of color paint).

This is due to the fact that infrared light generally penetrates the upper layers and is then reflected by the ground and absorbed by the underdrawing. This differential absorption can be imaged by an infrared-sensitive camera.

Nowadays the traditional IR film has been mostly replaced by digital systems, which allow more reliable database creation, better image processing and enhancing, easy reproducibility of the reflectograms, and, most important, a higher image quality, in particular as far as paint penetration is concerned.