The last recovered quarter of La pose enchantée, a 1927 René Magritte oil painting which disappeared in 1932, has been used to create a virtual colorization of the original. Researchers at the Royal Museums of Fine Arts of Belgium and the University of Liège used techniques including high-resolution photography under visible and ultra-violet light to analyse the paint used in the discovered quarter and suggest how the painting may have looked as a whole. Their findings are published in the open access journal Heritage Science.

The researchers found the final piece of the lost painting under another Magritte picture, Dieu n'est pas un saint, during a radiographic examination of paintings from the Magritte Museum collection.

Dr. Catherine Defeyt, the corresponding author said: 'Imaging and analysis of the painting provided lots of information about the hidden picture, especially in regards to the palette used. For example, the deepest blue layer, visible under the microscope and appearing lighter and greener than the upper ones, is presumed to be a tiny part of the sky from La pose enchantée. Analysis and observations such as this allowed us to propose a virtual colourisation of the painting.'

The in-depth study conducted on the double picture included a variety of techniques. The authors first photographed full size images of Dieu n'est pas un saint under visible and UV light to carefully study its appearance and look for evidence of La pose enchantée. Next, they used X-ray radiography imaging, which reveals the different layers of a painting, to view the picture underneath. In order to get a better understanding of the paint used by Magritte, the researchers utilised X-Ray Fluorescence spectroscopy to look at each area of the painting in turn and analyse the pigments in that area to get a better idea of the colors used.

Dr. Defeyt said: 'The precarious financial situation that Magritte was in between 1920 and 1935 led him to regularly reuse canvases from former paintings, so it is not surprising to find La pose enchantée beneath another painting -- especially as the other three quarters were found in similar situations. The double painting provides a challenge for those examining the picture and various scientific imaging and analytical techniques were required to assess the materials and techniques used.'