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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."
http://graphics.stanford.edu/projects/lightfield/ If you've attended siggraph for the last 8 or 9 years you yawn with me.
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.
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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 :)
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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.
I'm not wrong. You haven't thought about it hard enough.
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.
Occam's razor is the blind faith in the natural selection of least resistance and in universal oversimplification. -- EF
When you sharpen an image in Photoshop (or Gimp) you are only increasing the contrast. While this has the effect of making the image "pop out" more which looks sharp it can't extract more detailed information from the image.
Sounds like this is a popularized writeup about the work that was just published at SIGGRAPH in July. So it's more recent than 1996.
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...
No, sharpening in Photoshop also enhances high frequencies in the image, which gives the impression it's more in focus because it does have sharp artifacts in it.
It is possible to truely sharpen an image (a little bit) using deconvolution. But it won't get you CSI style sharpening.
I wonder about the effect on resolution and sensitivity of this technique. Modern autofocus on little point and shoot cameras is pretty good at what it does... a lot of blurry pictures are due to camera shake because poor lighting requires long exposure times. The article even mentions "poor lighting" although it somehow assumes that this technique will fix that too.
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.
No, you can't, and you're completely right about that. But in the out-of-focus picture all the information is (mostly) there, and the question is how to transform that desired subject in focus. If you have the convolution model, you can write an inverse function using Fourier transform. For a quick mathematic formula, see here and scroll a little down until you find section "Wrong lens focus". There's also software that does the trick. The downside here is that it increases the noise as you can see on the focusmagic examples, but nevertheless it's possible and already done. The original work that represents the degradation model is from the 60's.
?SYNTAX ERROR