Refocusable Plenoptic Light-Field Photography

virgil_disgr4ce writes "Wired is reporting that a Stanford student using about 90,000 microlenses has developed a plenoptic camera whose images can be refocused, via software, after they are exposed." From the article: "'We just think it'll lead to better cameras that make it easier to take pictures that are in focus and look good,' said Ng's adviser, Stanford computer science professor Pat Hanrahan."

Comments

oh so 1996

[griffster]

http://graphics.stanford.edu/projects/lightfield/ If you've attended siggraph for the last 8 or 9 years you yawn with me.

"Say Sayonara to Blurry Pics"???

[5, Troll]

This is great technology but the author of the article used an incorrect title. Blurry photos are almost always caused by camera shake, not focusing on the wrong subject in a depth of field situation.

This technology doesn't do anything to prevent camera shake. Most modern cameras are extremely good at autofocusing on the correct subject in a short depth of field situation. The camera designed by the Stanford guys is an amazing invention and will revolutionize action, sport, and scientific photography (especially at the macro level) but it will do nothing special for the consumer who simply doesn't understand that the longer the exposure the more likely the blur from camera shake.

Re:"Say Sayonara to Blurry Pics"???

[fireman sam]

It article states "This property allows us to extend the depth of field of the camera without reducing the aperture, enabling shorter exposures and lower image noise". This in itself will reduce the effects of shaking.

Re:"Say Sayonara to Blurry Pics"???

[Digital11]

Which would normally cause undesirable camera-shake in such a situation due to the decreased shutter speed

Re:"Say Sayonara to Blurry Pics"???

[HuguesT]

Read The Fine Article. The proposed solution is almost the exact opposite to the one you are talking about.

The microlens approach doesn't require any moving part, it allows not only to refocus but also to extend focus as if one were using a very high F-stop for large depth of field, without the associated noise due to low light.

The downside is that it requires many pixels to produce a good image, but as the pixel count grows exponentially with time as per Moore law, it will soon be a winning proposition, even with cameras in mobile phones.

On the other hand optical stabilization is as expensive as ever, requires many moving parts and does not allow focus extention.

Re:3d Images

[griffster]

There was a demo by Sony at GDC 2005 where they had a next generation "eye-toy" that could (essentially) extract a Z buffer with the captured image. they had some very cool demos... the most memorable was a virtual butterfly that flew around the head of the demonstrator and then landed on his arm :)

Can't get something for nothing

[Deep Fried Geekboy]

The more potential focal points you want, the less resolution you can have for any particular one of them. You have to record information for all possible focal points on the CCD. Conceptually it's no different from, say, dividing the CCD into four parts and recording an image with a different focal point on each of the quarters, then post processing to combine them as required. I think. So photographically speaking the image is degraded compared to just getting the focal point right in the first place. Which isn't to say there aren't cool things you can do with it.

Re:innovation

[RedWizzard]

As soon as I heard of this, I immediately realized how to do it. But I would not have thought to do it on my own. This kind of smart thinking is why we have a patent system. The patent system was not designed to protect business methods, such as completing a sale using n clicks instead of n+1.

The patent system is not meant to protect an idea either. It's meant to protect a non-obvious implementation of an idea.

Re:innovation

[Directrix1]

If you look at this site: Stanford Lightfield Project. You will see that the basic premise behind defining a light field and mathematically manipulating it has been around sine the 30's. Whats cool here is the camera. In fact being in the photography business myself, I was just telling my father a couple months ago about how it would be easy to refocus an image if there was a lense that just captured a grid of images with slightly different perspectives from each cell. Refocusing the light field is a pretty obvious benefit to this system, I would deem not worthy of a patent, as it is just a way to mathematically manipulate a light field.

You don't really lose resolution

[mrmojo]

I'm one of the guys who works on this stuff at Stanford. I should point out that it's not fair to say you lose resolution, because good cameras have large pixels to reduce noise over a finite exposure time. Lightfield cameras, because they add up a whole lot of individual pixel samples to produce an image pixel, can get away with much much smaller pixels, because the noise goes down as you sum up the pixel values.

The best way to think of it is take a standard good quality camera with big pixels, subdivide each pixel into a grid of 12x12 or so tiny pixels - more like the size of pixels in cell phone cameras - and put a microlens over it. You get the same spatial resolution as the good camera, roughly the same noise characteristics, and the ability to refocus and pull other light field tricks like hitchcock zooms.

You just have to be aware that treating the data as a light field it's very noisy, like a crappy cell phone camera, but when you add up pixels to make a focused image, the noise drops back to regular good camera levels.

It's just harder to deal with the amount of data you get off a large sensor with tiny pixels, and they're also harder to build, but neither point is a showstopper and these are mere engineering issues...

Re:X-Ray enhancement?

[HuguesT]

Not with this camera, as X-Rays are hardly ever focussed (they don't bend easily!). Here is an image of a rare and expensive X-ray focussing mirror. You have to use grazing incidence for it to work.

Medical X-ray photographies are simply taken by placing film (or these days a digital detector) behind the body and lighting with X-rays. No focussing is involved.