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Monday, December 19, 2016, 09:05

All the colours of the rainbow

By Li Yinze

A breakthrough by a research team in Hong Kong is set to allow color-blind people to view almost natural colors on screens. Li Yinze reports.

All the colours of the rainbow

The color blind Aussie businessman was completely unprepared for what happened when he walked into the electronics fair and donned a pair of special glasses. For the first time in his life he could distinguish the colors red and green. Peter Marragg has suffered from color blindness all his life.

What made the experience even more important to him was the knowledge that from now on he could see those colors through the glasses, while enjoying a movie or a television program with his family, who are not color blind.

Computer and engineering scientists at the Chinese University of Hong Kong (CUHK) made the breakthrough that opens up a whole new on-screen world of almost natural color for people like Marragg.

The breakthrough comes from manipulating the colors that often bedevil color deficient people onto two separate screens. The colors are reorganized on those screens to make the color distinctions easier to recognize for people with color blindness. The device has no effect on people with normal vision. They see the screen as they normally would.

“Red and green used to appear as the same color to me,” Marragg said, “but now I can easily distinguish the differences.”

The application, developed by computer scientist Samuel Shen Wuyao and his team, can be installed on any regular 3D display device. Color blind football fans now can distinguish between the colors of players’ jerseys.

All the colours of the rainbow
Samuel Shen Wuyao (first right) and his fellow research scientists. (Provided to China Daily)

The problem for color blind and color deficient people begins with the light receptors of the eyes — the rods and cones — which transmit information from the eyes to the brain.

The ability to distinguish color resides in the three different types of cones in the human eye. Generally speaking the cones are sensitive to red, blue and green, respectively.

Color blindness is a condition usually inherited through a faulty gene in the X chromosome from the mother. Because females have two X chromosomes, they usually compensate for deficiency in one, thus the vast majority of people affected by color deficiency are men.

All the colours of the rainbow

Telling red from green

A very large number of people have problems distinguishing colors when they do day-to-day work, using computers, for example, which limits their choices of occupation

Samuel Shen Wuyao, computer scientist and member of a Chinese University of Hong Kong team who created an application that can be installed on regular 3D display devices to help color blind people distinguish colors

The problem with color blindness is that the light-sensitive cones of the retina function at “below normal” sensitivity. Those afflicted with the deficiency are unable to discriminate between colors.

The most common type of color blindness, for example, is red-green color deficiency. Some people suffer from blue-yellow color blindness. People at the extreme end of color blindness can see only black and white.

The different colors we see are distinguished by their wavelengths on the electromagnetic spectrum, of which the visible spectrum is but a small part. The variability of the wavelength determines the colors people see. People with defective vision cannot perceive the “just noticeable” differences by which colors normally are perceived.

Although there is currently no cure for color blindness, the CUHK application provides color enhancement. The CUHK team developed an application that produces a pair of virtually identical images and displays them on the viewing device. The separate images are re-colored to emphasize the differences.

According to the type and severity of the patient’s color blindness, each image can be re-colored into hues and color saturations making the distinction clear.

The singular images we see combine the images picked up by the left and right eye. Seen through a pair of regular 3D glasses, each eye of the color blind patient receives only one of the two re-colored images. When the image is viewed as a single object by the brain, color blind people are able to distinguish the colors.

Shen and his team started research on the visual technology five years ago, when he learnt that color-blindness in Hong Kong was much more prevalent than he believed. Around the globe, it’s estimated 250 million people have color deficiency.

“A very large number of people have problems distinguishing colors when they do day-to-day work, using computers, for example, which limits their choices of occupation,” he said.

To enable color-blind people to distinguish colors, scientists had to understand how color is perceived in the brain and simulate the process. That meant collating information from a variety of color blind people over a long period of time.

All the colours of the rainbow

Shen has expressed his confidence that the application can be used in movie theaters, home television screens, mobile device screens, as well as wearable equipment, and would benefit many in the community.

Many major corporations, including Apple and Samsung, have expressed their interest in cooperating with the team, to make it easier for color blind users to see the screen.

“We, as scientists with rich knowledge and experience on color enhancement, should do something to help make a difference,” Shen said.

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