| Monday, January 28, 2008
Using a new algorithm, researchers are trying
to enhance picture quality so that those with macular degeneration can
enjoy television.
By Brittany Sauser
Enjoying a favorite TV show can be difficult
for someone with macular degeneration. Like many kinds of visual impairment,
macular degeneration makes the images on the screen seem blurred and distorted.
The finer details are often lost. Now researchers at the Schepens
Eye Research Institute have developed software that lets users manipulate
the contrast to create specially enhanced images for those with macular
degeneration.
"Our approach was to implement an image-processing
algorithm to the receiving television's decoder," says Eli
Peli, a professor of ophthalmology at Harvard Medical School and the
project leader. "The algorithm makes it possible to increase the contrast
of specific size details."
The researchers focused their work on patients
with age-related macular degeneration, a disease in which the macula--the
part of the eye that's responsible for sharp, central vision--is damaged.
According to the American Macular Degeneration
Foundation, more than 10 million Americans suffer from the disease,
which often leaves those afflicted with a central blind spot. A patient's
remaining vision is often blurred, making it extremely difficult for people
to watch television or even read the paper, says Mark O'Donoghue, clinic
director of the New England College of Optometry's
Commonwealth Avenue Clinic. "This is really new and fascinating to read
about," says O'Donoghue. "I recognize the basic facts in the technology
and the path of physiology in which [Peli] is doing this, and it is innovative."
Peli and his group currently have the new
software running on a computer in their lab, but they're expecting to receive
a prototype system built by Analog Devices
in April 2008.
Peli's group discovered that patients suffering
from macular degeneration could not perceive high-frequency waves in the
visible spectrum, which left them unable to see fine details.
In order to give the patient a much better
chance of discerning the image, the researchers designed an algorithm that
specifically increases the contrast over the range of spatial frequencies
that the visually impaired could see: the middle and low frequency waves.
Ultimately, Peli says, the system enhances the contrast of the picture,
and the result is that the finer details are more evident. |
The contrast can be adjusted by a user in
much the same way that one would change the volume on a TV using a remote
control. O'Donoghue likens the system to a stereo equalizer for the eyes
that allows TV watchers to fine-tune the picture.
To measure the amount of image enhancement
that individuals prefer, the researchers recently conducted a study using
24 patients with visual impairments and 6 normal-sighted people. The subjects
sat in front of a television and watched four-minute videos, adjusting
the level of contrast with a remote control. The researchers found that
all the subjects--even the normal-sighted people--wanted some level of
enhancement, and the majority of the time a subject chose the same level
of enhancement whether they were watching a dark scene or fast action,
says Peli. (The amount of enhancement selected correlated to the severity
of the subject's vision loss.) The study was published last month in the
Journal
of the Optical Society of America.
One day, this system could transform watching
TV alone or with the family into a more "rewarding experience" by making
it easier for people to pick out the objects of interest from their surroundings,
says Tom O'Donnell, an assistant professor at the University of Tennessee's
Hamilton Eye Institute.
Peli hopes that the system will eventually
be incorporated into the menu options for all televisions. Ideally, people
will have the option to see an enhanced view just as the hearing impaired
have the option to call up captions, he says.
Enhanced vision: Researchers at the Schepens Eye Research Institute have
developed software that lets users enhance the contrast of images on a
television screen. In the image above, the screen is split: on the left
is an unenhanced television picture, and on the right is a picture with
the contrast enhanced.
Credit: Schepens Eye Research Institute
Multimedia
• Watch
enhanced video.
• Compare
normal and enhanced images. |
