Lens-Free Flat Cameras Make Use of Pinhole Technology (npr.org) 65
RhubarbPye writes: As reported on NPR, "Engineers in Texas are building a camera that can make a sharp image with no lens at all." By incorporating millions of individual pinholes with photoreceptors and postprocessing software, this camera system has been reduced to minimal thickness. Cameras in the wallpaper? A new phase of wearable cameras? What other applications for this technology could be developed?
I want to put my money into a hole (Score:2)
Looks like someone decided to put their money into a hole.
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I was looking for the "Nothing to see here" joke.
Who is responsible for this hideous omission?
On a more serious note, the headline was rather sensationalistic. My first thought was "pinhole", but perhaps I know too much about the history of optics and photography?
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Yes [tvtropes.org]
Re:I must be missing something... (Score:4, Informative)
So, let's see if I get this right. They rediscovered something, that everyone from the 1990's and 80 years prior learned to make as part of science class...and simply applied modern technology to it.
No, you didn't get it right. But that's not surprising, clearly you didn't read the article.
Re:I must be missing something... (Score:4, Interesting)
I suspect that if you put a lens on it, you would end up with a light field camera.
aaaaanyways... this is wikipedia on light field camera: "A light field camera, also known as plenoptic camera, captures information about the intensity of light in a scene, and also captures information about the direction that the light rays are traveling in space. One type of light field camera uses an array of micro-lenses placed in front of an otherwise conventional image sensor to sense intensity, color, and directional information. Multi-camera arrays are another type of light field camera. Holograms are a type of film-based light field image."
which sounds almost exactly like a variation of this. it's the same exact concept.
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http://www.kshitijmarwah.com/index.php?/research/compressive-light-field-photography/ [kshitijmarwah.com] (From MIT Media Lab)
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I think the "micro mask" is the lens array. It already is a light-field camera.
I can't wait to see what these things start to be capable of as technology progresses to assemble the micro structure and we get over the computational overhead
Massively parallel pinhole camera (Score:3)
So, let's see if I get this right. They rediscovered something, that everyone from the 1990's and 80 years prior learned to make as part of science class...and simply applied modern technology to it.
No, you didn't get it right. But that's not surprising, clearly you didn't read the article.
What? Even TFA itself mentions that the researcher decided to go back to the classical pinholes as inspiration:
To design their camera, Baraniuk and his colleagues looked to the past for inspiration.
"Back to really the very first cameras, pinhole cameras," Baraniuk says.
Pinhole cameras have been here for quite a while. According to some scholars, they were first described by the Chinese philosopher Mo Ti around 400 B.C
Basically they've taken the pinhole camera, and decided "We have computing power !"
Instead of putting just one camera (which would definitely NOT gather enough light at this size), they're massively parallelized it. They've put millions of pinholes camera on the chip and are using post processing to reconstruct the final image out of the tons of tiny pinhole views.
In away their doing exactly what l
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Instead of putting just one camera (which would definitely NOT gather enough light at this size), they're massively parallelized it. They've put millions of pinholes camera on the chip and are using post processing to reconstruct the final image out of the tons of tiny pinhole views.
I think there are more pinholes of a variety of different shapes, and fewer sensor pixels than your description might suggest.
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TFA:
To design their camera, Baraniuk and his colleagues looked to the past for inspiration.
"Back to really the very first cameras, pinhole cameras," Baraniuk says.
Pinhole cameras have been here for quite a while. According to some scholars, they were first described by the Chinese philosopher Mo Ti around 400 B.C
No, you didn't get it right. But that's not surprising, clearly you didn't read the article.
Apparently I did. How the hell your comment got to informative I have no clue.
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They didn't rediscover it. They knew about it all along, but figured out a way to actually make it useful in this application. So your claim was incorrect.
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To design their camera, Baraniuk and his colleagues looked to the past for inspiration.
That's effectively rediscovering it.
Re: I must be missing something... (Score:1)
This technology has many holes. It looks like there is no limit of how many holes you can have. I would imagine that with enough holes you get super accurate photos from space. And most likely it will be much cheaper.
Re:I must be missing something... (Score:4, Insightful)
Actually it's more like the compound eye of insects, but 'wired' differently.
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A pinhole camera is educationally interesting but not much use for practical purposes. You simply don't get enough light coming though. It's easily solved by optics. Most cameras use a lens to squeeze more light through the aperture. But this requires a certain thickness. Not a problem if you can afford a few CM of thickness, but unsuitable for flat cameras.
You can also solve the problem by using lots of pinholes. But if you use a si
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Single pinhole cameras have severe quality limits. Make the hole too big and sharpness is inversely proportional to the diameter of the hole. Make the hole too small and sharpness is proportional to the size of the hole, and the amount of light is reduced also. For best sharpness there's an optimum pinhole diameter { 1.9 * sqrt ( f * l ), where f is focal length and l is wavelength }, and the results even at the optimum aren't very good.
Multiple pinholes offers a theoretical way around the diffraction limi
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and the results even at the optimum aren't very good.
You might be surprised if you do an image search for "photos taken with a pinhole camera."
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Dynamic range? (Score:5, Insightful)
Re:Dynamic range? (Score:5, Insightful)
No. First, on these you are mostly limited by the thermal noise of the sensor which is miles above the photon noise for this application. Then you are still thinking that a pixel receives the same flux (power per surface area) as a traditional camera. This is not correct as each of the pixels collect flux from a much larger angular portion of the scene (due to the lack of optical focusing).
Re:Dynamic range? (Score:5, Informative)
If you have to solve a big giant matrix inversion to do the job of a collimating lens, you're composing each pixel as a sum of many others instead of just itself, some of them being way brighter than the reconstructed image, meaning your reconstructed pixel is always noisier.
Not really.
When you average a large number of samples the noise tends to partially cancel out while the signal keeps adding up. Though the noise goes up with more samples, the signal goes up more, improving the signal to noise ratio. Even if you end up adding in some bright signals, with extra noise, that's still stomped by signal when you have enough samples.
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No, the original poster was more correct. They're not averaging together a bunch of pixels, but applying an inverse matrix , which will weigh pixels differently, and quite frequently can involve very high weights assigned to noisier signals. This can result in an emphasis that amplifies noise. There is a lot of work done on different ways of clipping or modifying such matrix equations to make it slightly less accurate in an ideal world, but much less noisy in the real world.
Also, no averaging of noise w
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Also, no averaging of noise will happen if you try to produce images with similar pixel count to the number of detectors.
I agree completely there. (I'd say there is averaging but you're averaging in as much extra noise from other pixels as you're averaging out from multiple samples of the target pixel - and even if the noise were merely proportional the pixel brightness, rather than disproportionate as they get brighter, the bright ones would noise up the dim ones.)
They're not averaging together a bunch of
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No. As someone with patents on multiplex imaging, I can tell you that inverse problems lead to greater noise or equivalently reduced dynamic range. You can see this in their photos.
Millions of pinholes * near zero size = ?? (Score:3)
Nothing in the article talks about what the resulting aperture is. To get a reasonable exposure time, you need to capture adequate light. Cameras in cell phones already suffer because their lenses are too small to capture enough light. Is this scheme worse because it lets less light through or better because a larger "lens" is practical?
Scalable (Score:3)
Is this scheme worse because it lets less light through or better because a larger "lens" is practical?
Currently, it's worse (TFA mentions quality similar to first gen webcams).
But indeed, that technology is really scalable. TFA muses with large surface flatcams.
(They mention walls of it. Or boxes/cylinder in the middle of which you put an object, etc.)
So the whole back cover of a smart-phone could be a giant pinhole array.
Such a large surface even if covered with only pinholes (and even if some of the hole might get obscured by fingers holding the phone) would gather much more light and information and coul
What would be interesting... (Score:1)
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Seems like a good idea. (Score:2)
The Irony (Score:2, Funny)
VR is the hot new thing (Score:3)
Your next webcam (Score:1)
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Nothing is new under the sun? (Score:5, Interesting)
Coded aperture imaging (CAI) (Mertz and Young, 1961; Dicke, 1968) has matured as a standard imaging technique in X–ray and Gamma-ray astronomy. It is capable of combining high angular resolution with good photon collection efficiency by using a mask consisting of transparent and opaque elements placed in front of a position sensitive detector (Figure 1).
So is the only innovation here using more pinholes, more pixels, and more processing than were around in the 1990s?
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Yeah, reminds me of sparse imaging / compressive sensing too. Nothing new here except perhaps they aim for a consumer product. I would still welcome any device capable of imaging at high resolution and wide dynamic range without a lens. Lenses are so medieval, we should do better.
As their paper points out, these pinhole systems really suffer from the fact the the imaging aperture is TINY. This produces a low resolution, high depth of field image like a camera with a very "high / slow" F/# .
High degrees of multiplexing also require high bit depth measurements and low noise, driving sensor cost up.
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FlatCam is an instance of a coded aperture imaging system; however, unlike the vast majority of related work, we place the coded mask extremely close to the image sensor that can enable a thin system.
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It's the flatness and the lateral extensibility (wall paper sized) that are new for coded aperatures
It will still be a bit bulky I guess (Score:2)
I assume that you still have to make the surface with all the pinholes in, a little convex. If only to not just capture the same square cm in front of the lens a thousand times.
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I don't think so. Each pinhole can produce an image corresponding to a wide angle which only depends of the size of sensor of its distance from the pinhole. If the sensor is very close to the pinhole(s) then the image will have a wide angle (up to 180 degrees).
Integral MicroOptics from the 1980's (Score:2)