An impressionist work from 1891 has been authenticated through modern technology as the work of Claude Monet. Scientists used a hyperspectral camera to reveal the artist's signature under layers of paint.

Monet apparently painted over his own signature, say the researchers from the University of Jyväskylä in Finland. Layers of paint hid the signature on 'A Haystack in the Evening Sun,' from the artist's prized haystack series.

"The hyperspectral camera took an image of 256 different wavelengths simultaneously in the near-infrared region," said researcher Ilkka Pölönen in a statement. "This wavelength region is not visible to the human eye. Many of the painting's pigments which have been used and are still used today are there in the wavelength range which is partially and even completely transparent. In this case, the light reflection can be measured from the surface layer and deeper."

The painting has been owned by Finland's Gösta Serlachius Fine Arts Foundation for more than 50 years.

Other Monet haystack paintings reside at the Art Institute of Chicago, the National Gallery of Scotland and the J. Paul Getty Museum in California.