Posted on 11/17/2005 11:50:52 AM PST by LibWhacker
BLURRY snaps could be a thing of the past with the development of a digital camera that refocuses photos after they have been taken.
The camera could be useful for action shots taken by sports photographers or for CCTV surveillance cameras, which often produce fuzzy shots due to poor lighting.
In an ordinary digital camera, a sensor behind the lens records the light level that hits each pixel on its surface. If the light rays reaching the sensor are not in focus, the image will appear blurry.
Now, Pat Hanrahan and his team at Stanford University have figured out how to adjust the light rays after they have reached the camera. They inserted a sheet of 90,000 lenses, each just 125 micrometres across, between the camera's main lens and the image sensor. The angle of the light rays that strike each microlens is recorded, as well as the amount of light arriving along each ray.
Software can then be used to adjust these values for each microlens to reconstruct what the image would have looked like if it had been properly focused. That also means any part of the image can be refocused - not just the main subject.
Tracing the rays like this removes the conventional trade-off between the aperture size, which controls the amount of light that the camera takes in, and the depth of field. If light is low, a larger aperture will let enough light into the camera to form a clear image, but the laws of optics mean that a narrower slice of the world in front of the camera will appear in focus.
Hanrahan's system would be particularly useful for surveillance cameras, which must work at night but also need to have objects in focus at different distances from the camera.
amazing concept, although it sounds like it will be extremely processor intensive to make such calculations on data from so many sensors, real time.
Too bad the Hubble Space camera didn't have one of these - could have saved few billion.
I'm in a circle of confusion over this.
That's okay; I am, too! I hope all the physicists and photographers here on FR pipe in soon and clear up some things for us. For instance, I'd like to know what kind of quality we can expect out of this sheet (plastic sheet?) of 90,000 microlenses? You don't want to shove a sheet of cheap plastic in front of a $10,000 lens!
In all seriousness though, haven't insects been doing something like this for a while?
If I'm reading it right, it doesn't *have* to be processed in "real time". Instead, the system just takes a "snapshot" (no pun intended) of the light intensities and angles at the moment the shutter is triggered, and then this records all the information necessary to produce images at any *later* time via processing of that dataset.
"I'd like to know what kind of quality we can expect out of this sheet (plastic sheet?) of 90,000 microlenses? "
Microlenses are not new. Most CCD devices contain them. DLP technology used in some video projectors today contains millions of tiny mirrors on pivots and moves them as needed to gather correct amounts of red, blue, and green light. "They" can do some pretty amazing and tiny things these days! Also, $10K won't even touch a broadcast quality HDTV lens. Heck, it can cost that to fix one!
What? Designing and building digital cameras? (Not at all serious.)
It did, but the in focus pics are still sharper. Hubble was corrected with software prior to the repair. If you know the exact physical characteristics of a lens you can write software to correct its imperfections.
Absolutely. The common housefly has an eye like that. Now if the fly's tiny brain is somehow hardwired to do what these Stanford reseachers have done with their software, then I am very impressed, and it's a hopeful sign for the future of this technology.
Shutter bugs?
You'll probably tell me to get my tinfoil hat on, but I've always thought that the Hubble was intentionally flawed when it was launched. It was just too convenient that NASA was able to so easily come up with a fix that just happened to require a spacewalk to fix, this coming at a time when NASA was beginning to be seen as irrelevant and unnecessary. Suddenly, NASA was able to prove that they could repair a massive telescope in space! Too much coincidence for me.
So the next time you kill a fly, you are quite possibly wiping out a tiny supercomputer optimized to convolve a gabor transform kernel on the cached hits of an orthogonal range search traversal of a photon map. Something to think about.
Worse, news of this put my sister into a coma.
True, but you can never recover signal lost in noise.
They'll have a dedicated image processing IC to handle these in no time. It will probably be nearly instantaneous.
Not quite true. You can recover a signal that is below the noise level if you know the characteristics of the signal. GPS receivers do this.
Hopefully the software can decide not to focus, if, say, Hillary were to be in the background.
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