In December, MIT Media Lab researchers caused a stir by releasing a slow-motion video of a burst of light traveling the length of a plastic bottle. But the experimental setup that enabled that video was designed for a much different application: a camera that can see around corners.
By using optical equipment in a totally unexpected way, MIT researchers have created an imaging system that makes light look slow.
MIT researchers have created a new imaging system that can acquire visual data at a rate of one trillion exposures per second. That’s fast enough to produce a slow-motion video of a burst of light traveling the length of a one-liter bottle, bouncing off the cap and reflecting back to the bottle’s bottom.
Media Lab postdoc Andreas Velten, one of the system’s developers, calls it the “ultimate” in slow motion: “There’s nothing in the universe that looks fast to this camera,” he says. Continue reading »
Reported by Gretchen Cuda Kroen, in ScienceNow, on 7 October 2011.
It’s something we all take for granted: our ability to look at an object, near or far, and bring it instantly into focus. The eyes of humans and many animals do this almost instantaneously and with stunning accuracy. Now researchers say they are one step closer to understanding how the brain accomplishes this feat.
Wilson Geisler and Johannes Burge, psychologists at the Center for Perceptual Systems at the University of Texas, Austin, have developed a simple algorithm for quickly and accurately estimating the focus error from a single blurry image-something they say is key to understanding how biological visual systems avoid the repetitive guess-and-check method employed by digital cameras. The discovery may advance our understanding of how nearsightedness develops in humans or help engineers improve digital cameras, the researchers say.
Reported by Hamish Pritchard Science Reporter, BBC News, 13 Sep. 2011.
A sophisticated new camera system can detect lies just by watching our faces as we talk, experts say. The computerised system uses a simple video camera, a high-resolution thermal imaging sensor and a suite of algorithms.
Researchers say the system could be a powerful aid to security services. It successfully discriminates between truth and lies in about two-thirds of cases, said lead researcher Professor Hassan Ugail from Bradford University.
Reported by Savvas Chatzichristofis, 25 Aug. 2011.
This book covers the state of the art in image indexing and retrieval techniques paying particular attention in recent trends and applications. It presents the basic notions and tools of content-based image description and retrieval, covering all significant aspects of image preprocessing, features extraction, similarity matching and evaluation methods. Particular emphasis is given in recent computational intelligence techniques for producing compact content based descriptors comprising color, texture and spatial distribution information. Early and late fusion techniques are also used for improving retrieval results from large probably distributed inhomogenous databases. The book reports on the basic international standards and provides an updated presentation of the current retrieval systems. Numerous utilities and techniques are implemented in software, which is provided as a supplementary material under an open-source license agreement. The book is particularly useful for postgraduate students and researchers in the field of image retrieval, who want to easily elaborate and test state of the art techniques and possibly incorporate it in their development.
Doctors could one day instantly detect cancers by photographing patients with a digital camera.
Jeppe Seidelin Dam and colleagues at the Technical University of Denmark in Roskilde are developing a device that can convert infrared radiation into visible light. Attached to a digital camera fitted with an infrared flash, it could detect tumours by recording the telltale pattern of infrared light they reflect.
“This would allow a surgeon to quickly determine if the entire tumour has been removed before finishing an operation,” he says.
At the heart of the system is a multilayered crystal of potassium titanium oxide phosphate in which the infrared photons from the object to be imaged interfere with photons from an infrared laser, also fired into the crystal. The interaction shifts the wavelength into the visible spectrum while preserving the image information, allowing it to be captured by a normal camera.
The idea was first explored in the 1970s, but improvements to methods for growing crystals since then have improved the resolution of the device 300-fold. By placing a pair of mirrors on either side of the crystal so that the laser light reflects back and forth, the team increased the odds of its photons interfering with infrared photons from the object.
“We pass the same photons through the crystal up to 100 times,” says Dam. The crystal was able to capture an infrared panorama with a resolution of 200 by 1000 pixels, the team says.
The device could be placed in front of a digital camera lens like a filter, and be used to take thermal photographs or video. Shrinking it down to a size suitable for everyday use should not be difficult, says Dam. “These are basically the same components that are in green laser pointers.”
While current infrared colour imagers need to run at -200°C and cost around $100,000, Dam says that an upconversion imager would run at room temperature and cost about $10,000.
Stefano Bonora of the University of Padua, Italy, calls the upconversion technique “really interesting” for its potential to generate infrared images at room temperature. Such detectors are lacking at the moment, he says.
Journal reference: Optics Letters, DOI: 10.1364/OL.35.003796
Call it CSI: Abracadabra. A camera that can make invisible substances reappear as if by magic could allow forensics teams to quickly scan a crime scene for blood stains without tampering with valuable evidence.
The prototype camera, developed by Stephen Morgan, Michael Myrick and colleagues at the University of South Carolina in Columbia, can detect blood stains even when the sample has been diluted to one part per 100.
At present, blood stains are detected using the chemical luminol, which is sprayed around the crime scene and reacts with the iron in any blood present to emit a blue glow that can be seen in the dark. However, luminol is toxic, can dilute blood samples to a level at which DNA is difficult to recover, and can smear blood spatter patterns that forensic experts use to help determine how the victim died. Luminol can also react with substances like bleach, rust, fizzy drink and coffee, causing it to produce false positives.
The camera, in contrast, can distinguish between blood and all four of these substances, and could be used to spot stains that require further chemical analysis without interfering with the sample.
To take an image of a scene, the camera beams pulses of infrared light onto a surface and detects the infrared that is reflected back off it. A transparent, 8-micrometre-thick layer of the protein albumin placed in front of the detector acts as a filter, making a dilute blood stain show up against its surroundings by filtering out wavelengths that aren’t characteristic of blood proteins.
By modifying the chemical used for the filter, it should be possible to detect contrasts between a surface and any type of stain, says Morgan. “With the appropriate filter, it should be possible to detect [sweat and lipids] in fingerprints that are not visible to the naked eye,” he says. “In the same way you could also detect drugs on a surface, or trace explosives.”
Read more in Analytical Chemistry, DOI: 10.1021/ac101107v