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At MIT, they can put words in our mouths
By Gareth Cook, Globe Staff, 5/15/2002
CAMBRIDGE - Scientists at the Massachusetts Institute of
Technology have created the first realistic videos of people
saying things they never said - a scientific leap that raises
unsettling questions about falsifying the moving image.
In one demonstration, the researchers taped a woman speaking
into a camera, and then reprocessed the footage into a new video
that showed her speaking entirely new sentences, and even
mouthing words to a song in Japanese, a language she does not
speak. The results were enough to fool viewers consistently, the
The technique's inventors say it could be used in video games
and movie special effects, perhaps reanimating Marilyn Monroe or
other dead film stars with new lines. It could also improve
dubbed movies, a lucrative global industry.
But scientists warn the technology will also provide a powerful
new tool for fraud and propaganda - and will eventually cast
doubt on everything from video surveillance to presidential
''This is really groundbreaking work,'' said Demetri
Terzopoulos, a leading specialist in facial animation who is a
professor of computer science and mathematics at New York
University. But ''we are on a collision course with ethics. If
you can make people say things they didn't say, then potentially
all hell breaks loose.''
The researchers have already begun testing the technology on
video of Ted Koppel, anchor of ABC's ''Nightline,'' with the aim
of dubbing a show in Spanish, according to Tony F. Ezzat, the
graduate student who heads the MIT team. Yet as this and similar
technology makes its way out of academic laboratories, even the
scientists involved see ways it could be misused: to discredit
political dissidents on television, to embarrass people with
fabricated video posted on the Web, or to illegally use trusted
figures to endorse products.
''There is a certain point at which you raise the level of
distrust to where it is hard to communicate through the
medium,'' said Kathleen Hall Jamieson, dean of the Annenberg
School for Communication at the University of Pennsylvania.
''There are people who still believe the moon landing was
Currently, the MIT method is limited: It works only on video of
a person facing a camera and not moving much, like a newscaster.
The technique only generates new video, not new audio.
But it should not be difficult to extend the discovery to work
on a moving head at any angle, according to Tomaso Poggio, a
neuroscientist at the McGovern Institute for Brain Research, who
is on the MIT team and runs the lab where the work is being
done. And while state-of-the-art audio simulations are not as
convincing as the MIT software, that barrier is likely to fall
soon, researchers say.
''It is only a matter of time before somebody can get enough
good video of your face to have it do what they like,'' said
Matthew Brand, a research scientist at MERL, a Cambridge-based
laboratory for Mitsubishi Electric.
For years, animators have used computer technology to put words
in people's mouths, as they do with the talking baby in CBS's
''Baby Bob'' - creating effects believable enough for
entertainment, but still noticeably computer-generated. The MIT
technology is the first that is ''video-realistic,'' the
researchers say, meaning volunteers in a laboratory test could
not distinguish between real and synthesized clips. And while
current computer-animation techniques require an artist to
smooth out trouble spots by hand, the MIT method is almost
Previous work has focused on creating a virtual model of a
person's mouth, then using a computer to render digital images
of it as it moves. But the new software relies on an ingenious
application of artificial intelligence to teach a machine what a
person looks like when talking.
Starting with between two and four minutes of video - the
minimum needed for the effect to work - the computer captures
images which represent the full range of motion of the mouth and
surrounding areas, Ezzat said.
The computer is able to express any face as a combination of
these faces (46 in one example), the same way that any color can
be represented by a combination of red, green, and blue. The
computer then goes through the video, learning how a person
expresses every sound, and how it moves from one to the next.
Given a new sound, the computer can then generate an accurate
picture of the mouth area and virtually superimpose it on the
person's face, according to a paper describing the work. The
researchers are scheduled to present the paper in July at
Siggraph, the world's top computer graphics conference.
The effect is significantly more convincing than a previous
effort, called Video Rewrite, which recorded a huge number of
small snippets of video and then recombined them. Still, the new
method only seems lifelike for a sentence or two at a time,
because over longer stretches, the speaker seems to lack emotion.
MIT's Ezzat said that he would like to develop a more complex
model that would teach the computer to simulate basic emotions.
A specialist can still detect the video forgeries, but as the
technology improves, scientists predict that video
authentication will become a growing field - in the courts and
elsewhere - just like the authentication of photographs. As
video, too, becomes malleable, a society increasingly reliant on
live satellite feeds and fiber optics will have to find even
more direct ways to communicate.
''We will probably have to revert to a method common in the
Middle Ages, which is eyewitness testimony,'' said the
University of Pennsylvania's Jamieson. ''And there is probably
something healthy in that.''
Compare original and synthetic videos from MIT on www.boston.com/globe.
Gareth Cook can be reached at email@example.com.
This story ran on page A1 of the Boston Globe on 5/15/2002. ©
Copyright 2002 Globe Newspaper Company.
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