How photos became fine art, Yazzy's at www.williamverdult.com

Muybridge - Horse. Vintage Collotype from Animal Locomotion, 1887

According to the BBC, anyone can take a photo - just point and click. How did it become a staple of the art world, where a single image can fetch millions?

"The eye and brain edit things out, so you only see the things you're interested in," says David Byrne, musician, artist and photographer.

"The camera sees what it wants to see, but it's not exactly what the eye wants to see. It's like having another eye that you hold in your hand, but it's an interesting, different kind of eye."

And art is all about looking at things differently. Even the very earliest photographs demonstrated this ability to pick up unexpected details.

In 1843, the pioneering British photographer William Henry Fox Talbot demonstrated the all-seeing power of his invention with a photo of Trafalgar Square, showing Nelson's Column under construction.

The column itself is almost irrelevant. What draws the eye is the sheer amount of detail captured, the thick detail of everyday life precisely rendered. It's even possible to read posters plastered to the hoarding, including a sign that says "Post no bills".

This minutiae of daily life is the stuff of contemporary art, be it in photographs, paintings or installations.

Self-portrait

Another staple of fine art is abstraction, and the Surrealists of the early 20th Century pushed the boundaries of photography as they did painting and sculpture.

Man Ray, for example, encouraged his cameras to trip and stumble, to make accidental discoveries, to day-dream in the half-light of the darkroom.

"Man Ray was such a natural maverick in photographic medium that he almost effortlessly discovered all these ways to be a photographer that no one had thought of before," says photo historian Haworth Booth.

"Like making photographs in the dark room just by scattering interesting objects on photographic paper and then just switching the light on very briefly to allow these objects to imprint themselves on the paper, and then just developing it out - no camera involved."

As a latecomer in the world of fine art, photography has always found a place for rebels and the nonconformists.

William Klein, one of photography's living legends, returned from Paris to New York in the late 1950s with a wide-angle lens and a bad attitude. He cruised sidewalks with his camera, prying and provoking.

"I saw two kids playing cops and robbers and I said to one of them who had a gun 'hey, look tough'," he recalls.

The resulting image is one of Klein's most celebrated, says photo historian Colin Westerbeck. "Klein has managed to provoke him to an exasperation where the kid just takes the gun and sticks it right into the lens of the camera - it's so much inside the camera range that it's out of focus. There's another child in profile. He's caught in the crossfire and he makes the picture."

Klein himself regards it as a self-portrait. "I was this kid and I was this kid. I was timid and afraid of everything, and then I was also a kid who came on pretty strong. So I was both."

No limits

Among the first to advocate colour photos as serious art was Joel Meyerowitz, who in 1962 walked away from a career in advertising to photograph New York City's streets.

"I saw myself as a visual athlete," says Meyerowitz. "Every camera has a clock on it, it says a second and it says a 1,000th of a second and you can choose to work within those time constraints. And if you know what a 1,000th of a second is, you can believe that you see things in that split second. And if you believe it, you'll begin to see it."

Despite attempts to define and control what proper photography should be - that it should be in black and white, use no artificial lighting, and no amateurs - photography is a democratic medium. Anyone who picks up a camera is, for that moment at least, a photographer and many a happy accident turns out to be a striking image.

Someone once called photography "an unruly medium" and it is the unexpected directions it can go that has brought photos out of reportage and family snapshots and into galleries and auction houses.