Museo Thyssen-Bornemisza Bank of America - Merril Lynch
Infrared reflectography (IR) uses the infrared region of the light spectrum to penetrate the visible layers and obtain information from the under layers. As a type of radiation invisible to the naked eye, it must be captured and translated into a visible image using suitable technical resources.

With the IR reflectogram we can see the underdrawing beneath the layers of paint. These drawings, transferred to the canvas from preliminary sketches or cartoons, show up on the IR image if they are not done in red tones. In many cases they were modified by the artist during the creative process and do not match the final image.

There are different compositional phases: a rough preliminary sketch in whitish tones, and a second underdrawing with firmer, more clearly defined lines applied over the first, which reinforces, highlights or corrects groups and figures. These lines are almost entirely covered by coats of colour. New lines were added to correct the old ones or reinforce the final painting; these appear as firm brown coloured brushstrokes that emphasize certain features.