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Single-pixel camera captures high-quality, encryptable images

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December 29, 2010

The sequence shows the difference between the original image (obtained with a wrong key) a...

The sequence shows the difference between the original image (obtained with a wrong key) and the unencrypted one (Image: UJI)

In the crowded digital camera market, camera makers are continually pushing pixel counts higher and higher to attract consumers who have been led to believe that, the more pixels, the better the image. Proving that this is not necessarily the case, a team of researchers from Spain’s UJI (Universitat Jaume I) Optics Research Group (GROC) has developed a sensor of just one pixel with the ability to record high quality images.

CCDs

The CCD (charge-coupled device) sensors at the heart of today’s digital cameras record the electrical signals generated via the photoelectric effect in a large number of image points, known as pixels. This allows the light falling on a specific point on the sensor to be converted to a digital value. The CCD was invented in 1969 at AT&T Bell Labs by Willard Boyle and George E. Smith, with the two eventually recognized for their achievements by the Royal Swedish Academy of Sciences, which awarded them the Nobel Prize for Physics in 2009.

Nowadays, digital cameras with CCD sensors boasting millions of pixels are commonplace and, with the dimension of the sensors always the same (typically, 24.7 mm2), it is commonly believed that the higher the pixel count, the better the image quality. This is, however, not necessarily the case, with other factors – most notably, the quality of the lens – also playing a major role.

Single-pixel camera

The new single-pixel sensor developed by the UJI team goes against this common belief using a technique dubbed ‘ghost imaging’, which is based on the sequential recording of the light intensity transmitted or reflected by an object illuminated by a series of noisy light beams. This noisy light is what we observe, for example, when a piece of paper is illuminated using a laser pointer. To generate the necessary noisy light beams, the device uses a small one-inch LCD screen whose properties and features can be modified using a computer. The LCD screen is similar to home video projectors, but in miniature.

Using the single-pixel camera, the GROC team has successfully captured 2D object images such as the UJI logo and the face of one of the maids of honor from Picasso’s 1957 reinterpretation of the famous Las Meninas painting.

Encryption

The researchers have also demonstrated a secure way to distribute the high-quality images captured by the single-pixel camera over the internet using a method they say had not previously been used for image encryption. By transmitting the image as a simple numerical sequence, the image can be retrieved, but only by those who know the hidden codes used to generate the noise patterns that were used to create the image.

The team also hopes to use the same technology to capture images of internal biological tissues, which can be more difficult to view using pixelated devices, such as those commonly used in today’s digital cameras. Using this technique for image encryption, the researchers say, will improve secure image transmission, product authentication, whilst keeping information hidden from undesired viewers.

The first results of the UJI team’s study were published earlier this year in the journals Optic Letters and Nature Photonics.

About the Author
Bridget Borgobello Bridget is an experienced freelance writer, presenter and performer with a keen eye for innovative design and a passion for green technology. Australian born, Bridget currently resides in Rome and when not scribbling for Gizmag, she spends her time developing new web series content and independent cinema.   All articles by Bridget Borgobello
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10 Comments

The achievement is espetially interesting because of the encryption possibilities it offers. However, what is going to be most interesting to watch is the reaction of the marketing teams responsible for the 'megapixel count' wars.

Facebook User
30th December, 2010 @ 05:47 am PST

I don't get it? :(

Paul Anthony
30th December, 2010 @ 08:27 am PST

Is it just me or did this article really fail to explain how the heck a 1 pixel camera can produce a recognizable image with more than 1 pixel in it? Something about noisey light?...

Daniel G
30th December, 2010 @ 01:24 pm PST

Oh the simple things!

flibb
30th December, 2010 @ 02:17 pm PST

Bloody obvious. Noisy light. Of course! (uhm did the author of this article understand it? I don't)

Paul van Dinther
30th December, 2010 @ 08:30 pm PST

I think it works like this (gut instinct I have not looked into it)

Imagine the thing blinking say 100 times ... and each time it opens its eyes its assuming its looking at a predetermined angle.

So first blink it sees grey white black etc and associates "that color or tone must be somewhere in the top right of whatever view i have. then repeats the process with different areas ... so over time it's software re-creates what it was looking at.

Any area that isn't highlighted but its own light is effectively void to it.

So it can only see" one pixel at a time .. for each blink.

The problem is if several of these things exist they could mistake one camera's "first blink noisy light" as "theirs" and record "black" in the top left of their view when they shouldn't ... to prevent that happening each camera has its own unique key-set which is the light pulse signature it pays attention to... while ignoring others.

"Noisy light" - this is an active scanner... it doesn't use passive light, it has to make something then listen to its echo like sonar.

If i am right ... megapixel things can capture fast motion ... but something like this can only really make heads or tails of slower things - depending on your blink rate obviously. (- but assuming all components of a megapixel and it move at the same clock rate or blink rate ... megapixel wins).

How useful this tech is relates to it needing less physical things at high numbers or quality as one lazor, one pixel sensor ... and a bunch of software does the job you would otherwise need alot of hardware for.

So these things can get really small... suitable for nanotechnology big brother stuff on insects or a "more palatable reason" for grants and investment...

eyes which searching caves or dangerous areas... or you can make flocks of them and send them into space for very interesting views of nebula... make a hive mind coordination point and make them small ... many options. again, gut instinct I have not looked into it.

Facebook User
30th December, 2010 @ 10:24 pm PST

Rice Univ. did the same thing in 2006 (article at http://physicsbuzz.physicscentral.com/2006/10/single-pixel-camera.html) and Los Alamos did something that seems to be even closer to the UJI work all the way back in 1999 (http://www.osti.gov/energycitations/servlets/purl/758929-2rktOp/webviewable/758929.pdf). Remember that analog video was essentially a one-pixel (at a time) technology and the concept makes more sense.

Gary Fisher
31st December, 2010 @ 05:10 am PST

Yes, this sounds suspiciously similar to a how a scanner works, except without the moving scanning head (or drum for drum scanners). It sounds like it's high quality, but also probably very slow and can only photograph printed matter or something else that doesn't move at all.

Gadgeteer
1st January, 2011 @ 08:44 am PST

Yes it is very similar to the way a scanner works, but the key of the technology is not that idea.

Suppose the camera blinks 1000 times, it can easily capture a 1000 pixels image, each blink for 1 pixel. If it is this simple, the whole thing can be viewed as a trade-off between the size of the sensor and the number of captures.

Now what if the number of blinks can be reduced to a very small number, say only 10 times, then the system will be more useful right? The problem is the amount of data available is very small, and you will need complicated algorithm based on complicated mathematics to figure out the whole 1000 pixels data from only 10 pixels data captured from 10 blinks.

You may not believe it, but it is actually possible. Think about like the viewing an jpeg image or unzip a file. And this is the technology we are talking about. It is not as simple as how a scanner works.

Hoang Minh Chau
25th October, 2011 @ 06:18 am PDT

Amazing, positively amazing! I'm going to try to build one someday.

Sean Lijek
21st August, 2013 @ 08:45 pm PDT
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