Conservators at The Courtauld Institute in London have discovered an image of a mystery woman hidden beneath one of Picasso's most famous Blue Period paintings. The unknown image was discovered when The Courtauld took x-ray and infrared images of Portrait of Mateu Fernández de Soto (1901), revealing the outline of an unidentified woman with a distinctive chignon hairstyle, which was fashionable in Paris at the turn of the century.But the research also revealed evidence of another head at an even lower level in the painting, suggesting the canvas was much reused and painted over -- something Picasso, like other impoverished...