Under the faint grays, blues and yellows of 'Woman Ironing,' a 1904 piece painted during Picasso's Blue period modeled after a Degas painting of the same name, there has always been a ghostly image of a man waiting to be revealed.

According to the New York Times, conservators at the Guggenheim Museum — where the painting has hung since 1978 — have known about the man for years but only recently did the museum receive a grant that would help them clean up the mess that had been made of the painting over half a century ago.

In 1952, the painting was temporarily at the Musée d’Art Moderne. Because of a wayward thief who hoped to cut the painting from its frame by slashing its sides (and the signature), a conservator had to repair the sides and lined the canvas with linen, leaving glue on the surface.

It took them months to carefully clean the excess glue so that the mystery man could come into focus — but not to the naked eye. So, conservators decided to bring in an imaging specialist who used two types of sophisticated infrared cameras to produce detailed images that revealed the man's hairstyle, mustache and more.

Yet what remains to be determined is the identity of the man. Disagreement between the curators and restorers working on the piece led them to narrow it down to four possible subjects —one of whom his Picasso himself — who you can see here.

Take a look at whom they suspect the man may be in our slideshow at the bottom of the entry.

Though this is an excellent example of how painstaking care and meticulous restoration can produce astounding results, not all paintings have been so lucky. In August, an elderly volunteer went rogue on a fresco of Jesus at a museum in Spain, painting a destructive "restoration."

In happier restoration news, a man who received a painting attributed to 18th-century French master Claude-Joseph Vernet sent it to be cleaned, and when he received it he realized a lighthouse now stood where previously there had been just dark skies. This increased its value 16-fold, raising it from $40,600 to $650,000.

Take a closer look at "Woman Ironing" and the hidden painting here:

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  • Woman Ironing by Pablo Picasso

    The painting titled <em>Woman Ironing</em> by Pablo Picasso is seen in this image supplied by the Guggenheim Museum.

  • Infrared Imaging Reveals Painting Underneath

    An infrared analysis of the painting revealed another image underneath of an unknown man.

  • Painting Underneath Woman Ironing

    Flipped upright, the painting possibly could be a self-portrait of Picasso or a friend of the painter.