New research has found out how animal and human eyes use defocus to get focus right. In the near future this research may lead to digital cameras that focus instantaneously. y and fast.

January 16, 2012 @ 10:59AM

Accurate Auto-Focus in the Blink of an Eye

New research may lead to cameras that can focus as fast as a human or animal eye.

By Steve Meltzer

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News > New Products & Announcements

Our eyes focus far faster than the autofocus systems on our digital cameras. A new study by two University of Texas researchers, and their development of a simple focusing system using well known algorithms, may hold the answer to creating digital cameras that will focus as fast as our own eyes.

Modern digital camera cameras use one of two autofocusing systems. The simplest is the contrast detection system found in most compact cameras, Superzooms and lower end DSLRs. Focus is determined in this system by trial and error as the camera computes the contrast of a part of the scene, then changes the distance the lens is focused on and computes the contrast again. If it is higher, the camera senses it is going right direction and continues to change the focus and test contrast until the point of highest contrast is found. This take time and a lot of battery power.

Phase detection is the other system and it's found on high-end DSLRs. It is more expensive as it requires a beam splitter on the camera mirror to divide incoming light in two. Much like the split-image system of a rangefinder camera, the two beams reach an AF sensor that compares them and makes adjustments to the lens until the beams are identical and the lens is at the correct focus.

These systems are fast but the human eye is far faster. As we look at a scene, our eye focuses on each element in the scene so fast that we think that everything is in focus, when actually we are building a composite image in our minds. Camera makers have yet to duplicate this speed and accuracy with either of the existing technologies. Now there may be a focusing revolution at hand.

Johannes Burge, a postdoctoral researcher at the U of Texas and his adviser Wilson Geisler, wanted to understand how our eyes are able to focus so fast and efficiently. What they found may totally change the way digital cameras and other devices focus.

Their findings were published in an article in the Proceedings of the Journal of Science. In it they describe how human and animal eyes identify key features in a blurry image and use that information to find the distance to an object. With the distance found, the eye instantaneously focuses correctly.

"Many small predatory animals use 'defocus' as their primary depth cue," says Burge. "When a chameleon tracks a fly with its eye, there are muscles in the back of the eye that determine what the focus distance is."

From their finding, they developed a focus system based on it. Like animal eyes, their system takes in a whole scene and instantly finds the correct focus. Using some algorithms, they made a computer simulation of the human visual system which when presented with real world scenes, correctly focused. Burge points out that his system is simple enough to be incorporated in even the most inexpensive point and shoot camera.

Burge and Geisler are applying for a patent for their new technology and say they’ve already had interest from some "major imaging system" companies. They will present their work at a meeting of the International Society for Optics and Photonics at a conference in San Francisco.

If their research can be applied in thereal world, it is possible, that in the next year or two, we may be carrying digital cameras that will focus in the blink of an eye.