In this undated photo provided by Germany's Electron-Synchrotron, DESY, Wednesday, July 30, 2008, a special x-ray device used to detect a hidden portrait under the Vincent van Gogh painting ''Patch of Grass'' from 1887, center, is seen at a DESY laboratory in Hamburg, Germany. European scientists say they have developed a new method for extracting images hidden under old masters' paintings without harming them, and have unveiled a color portrait of a woman's face unseen since Vincent van Gogh painted over it in 1887. Joris Dik is a materials scientist from Delft University in the Netherlands. He says he used a particle accelerator and knowledge of metals in 19th century paint pigments to examine 'Patch of Grass,' a small oil study of a field that Van Gogh painted in Paris. [Agencies]