Topic Name: Barcodes for the rest of us:Tiny labels could pack lots of information, enable new uses
Category: Optical imaging
Research persons: Ramesh Raskar,Ankit Mohan
Location: Cambridge, United States
The ubiquitous barcodes found on product packaging provide information to the
scanner at the checkout counter, but that's about all they do. Now, researchers
at the Media Lab have come up with a new kind of very tiny barcode that could
provide a variety of useful information to shoppers as they scan the shelves --
and could even lead to new devices for classroom presentations, business
meetings, videogames or motion-capture systems.
The new system, called Bokode, is based on a new way of encoding visual
information, explains Media Lab Associate Professor Ramesh Raskar, who leads the
lab's Camera Culture group. Until now, there have been three approaches to
communicating data optically: through ordinary imaging (using two-dimensional
space), through temporal variations such as a flashing light or moving image
(using the time dimension), or through variations in the wavelength of light
(used in fiber-optic systems to provide multiple channels of information
simultaneously through a single fiber).
But the new system uses a whole new approach, encoding data in the angular
dimension: Rays of light coming from the new tags vary in brightness depending
on the angle at which they emerge. "Almost no one seems to have used" this
method of encoding information, Raskar says. "There have been three ways to
encode information optically, and now we have a new one."
The new concept will be presented this August in New Orleans at SIGGRAPH, the
leading international conference and exhibition on computer graphics and
interactive techniques. It is one of six papers, out of 439 technical papers
submitted, that was selected as a highlight of the conference. The lead author
of the paper is Media Lab postdoc Ankit Mohan. The co-authors, besides Raskar,
are graduate student Grace Woo, Shinsaku Hiura (a visiting professor from Osaka
University), and postdoc Quinn Smithwick.
The tiny labels are just 3 millimeters across -- about the size of the @
symbol on a typical computer keyboard. Yet they can contain far more information
than an ordinary barcode: thousands of bits. Currently they require a lens and a
built-in LED light source, but future versions could be made reflective, similar
to the holographic images now frequently found on credit cards, which would be
much cheaper and more unobtrusive.
"We're trying to make it nearly invisible, but at the same time easy to read
with a standard camera, even a mobile phone camera," Mohan says.
One of the advantages of the new labels is that unlike today's barcodes, they
can be "read" from a distance -- up to a few meters away. In addition, unlike
the laser scanners required to read today's labels, these can be read using any
standard digital camera, such as those now built in to about a billion
cellphones around the world.
The name Bokode comes from the Japanese photography term bokeh, which refers
to the round blob produced in an out-of-focus image of a light source. The
Bokode system uses an out-of-focus camera -- which allows the angle-encoded
information to emerge from the resulting blurred spot -- to record the encoded
information from the tiny tag. But in addition to being readable by any ordinary
camera (with the focus set to infinity), it can also be read directly by eye,
simply by getting very close -- less than an inch away -- to the tag.
As a replacement for conventional barcodes, the Bokode system could have
several advantages, Mohan says. It could provide far more information (such as
the complete nutrition label from a food product), be readable from a distance
by a shopper scanning the supermarket shelves, and allow easy product
comparisons because several items near each other on the shelves could all be
scanned at once.
In addition to conventional barcode applications, the team envisions some new
kinds of uses for the new tags. For example, the tag could be in a tiny
keychain-like device held by the user, scanned by a camera in the front of a
room, to allow multiple people to interact with a displayed image, for example
in a classroom or a business presentation. The camera could tell the identity of
each person pointing their device at the screen, as well as exactly where they
each were pointing. This could allow everyone in the room to respond
simultaneously to a quiz, and the teacher to know instantly how many people, and
which ones, got it right -- and thus know whether the group was getting the
point of the lesson.
The devices could also be used for the motion-capture systems used to create
videogames or computer-generated movie scenes. Typically, video cameras record a
person or object's motions using colored dots or balls attached to various parts
of the person's body. The Bokode system would allow the camera to record very
precisely not just the position but the angle of each tag -- with an accuracy of
a tenth of a degree. This is far more accurate than any present motion capture
Bokode "could enable a whole new range of applications," Raskar says. In the
future, they could be used in situations such as museum exhibit labels, where
the tiny codes would be unobtrusive and not detract from the art or other
exhibit, but could send a whole host of background information to viewers
through the use of their cellphone cameras. Or a restaurant could make its menu
available to a passerby on the sidewalk.
It could also replace RFID systems in some near-field communication
applications, Mohan suggested. For example, while RFIDs, now used in some ID
cards, can provide a great deal of information, that information can be read
from a distance, even when the card is inside a wallet. That makes them
inappropriate for credit cards, for example, because the information could be
retrieved by an unauthorized observer. But the Bokode could encode just as much
information, but require an open line-of-sight to the card to be read,
The prototype devices produced at the Media Lab currently cost about $5 each,
most of that cost due to use of an off-the-shelf convex glass lens, but Raskar
says that price could easily drop to 5 cents once they are produced even in
volumes of a few hundred units.
The work was supported by grants from Nokia, Samsung, and the Alfred P. Sloan
Foundation. The SIGGRAPH paper, "Bokode: Imperceptible Visual Tags for
Camera-based Interaction from a Distance," will be available online at the
conference website starting on Monday, July 27.