科技带领我们更深层次的认识艺术品

Just off Trafalgar Square at the National Gallery, some detective work is in progress: analyzing masterpieces, their pigment and varnish, to get into the mind of the painter. With infrared cameras and X-rays, it's possible to see right through the cracks. The evidence is all here: if a painter preferred his Muse is a blond, not a brunette, or that a portrait of a man was painted over, and reused as a canvas for another painting.

What the painter has done was to paint this portrait, then turned the canvas through 90 degrees, and painted the genre scene on top. But you can see from the X-ray very clearly the image of this colour underneath. And the reason that registers on the X-ray is it contains an X-ray dent or X-ray opaque pigment called lead white. And lead white blocks the passage of X-rays to the film. And so that then registers as white on the photograph.

What if one of these Lennon brothers didn't want anybody to see this? Why is it important to discover this is behind that painting?

Well, I think it tells you something about the life of that artist, the way their attitudes to painting. And indeed it tells you something about, for instance, 17th century portraiture which we didn't know. So I think discovering more about pictures doesn't harm the reputation of painters at all.

The findings so far are in the National Gallery's new exhibition 'Fakes, Mistakes, and Discoveries.' The touch-ups, the copies, and the forgeries are all on show, even the ones the Gallery itself bought and discovered decades ago they were fake, like this faux Botticelli.

There was a great scandal about the acquisition of this picture. It was bought by a man called Charles Lock Eastlake, who was the keeper of the Gallery at the time. And it really pretty well ended his career at the time. But it was bought by the National Gallery as a painting by Botticelli in 1874, at the same time as this picture of 'Venus and Mars' was bought.

Did the Gallery pay the same amount for each painting or…?

Unfortunately, in the 19th century we paid more for that one, which is interestingly, though, 600 pounds more.

You have the power to change the perception of a painting.

Yes, that's true. And there's a great deal of pleasure in that to be able to say what is correct, one hopes, what is correct about a picture, and to inform people about paintings that they love.

Science can help us understand the evolution of art. So if a picture paints a thousand words, perhaps by unpicking the process, we can learn the whole story.

Ayesha Durgahee, cnn, at the National Gallery in London.