Emerging tech Toolkit

Colour vision for the colour-blind

Tags:
ColorPath,
EyePilot

Candace Lombardi CNET News

Published: 19 Apr 2007 16:45 BST

The world may be in living colour, but not everyone sees it that way.

Peter Jones and long-time business partner Dennis Purcell, who met at Polaroid, have over the years developed technology for colour meters for commercial photography and film, and invented an architectural model camera that Polaroid, once a leading player in the photography business, licensed and produced.

Now at Boston-based Tenebraex — where Jones is president and Purcell is senior scientist — the two have taken their colour-technology knowledge into both the dark night and the digital world of colour-coded data.

Their refinement of the previously unsubstantiated Retinex theory of colour vision, put forward by Polaroid founder Edwin Land, may help soldiers carrying out night-time missions and bring some relief to the eight percent of American men and half a percent of American women who struggle daily with colour blindness.

Jones, the photographer turned entrepreneur, gives his opinion on colour blindness in a digital world driven by colourful data, and the stark reality of what colour night vision — technology that Tenebraex is pioneering — can do for the military.

Q: You've developed colour night vision and software for the colour-blind as well. How did you get interested in colour technology?
A: Both Dennis and I used to work for Polaroid in years past, back when they were a big deal, and colour was always of interest to us. Dennis actually invented a colour meter for photographers that Polaroid licensed back in the early 1980s. He came up with innovative ways for measuring the characteristics of light so you could come up with a set of filters that you could use on slide film, which was very intolerant of different kinds of light sources.

If Edwin Land's theory wasn't right, you would not see colour when you looked through our device

Peter Jones, president, Tenebraex

Dennis and I had invented a camera type that we had actually licensed to Polaroid and they put in production years ago. It was an architectural model camera. We've always had an interest in colour, in colour matters. Edwin Land (the founder of Polaroid) developed a theory of how your brain perceives colour, which he called Retinex theory, that we always thought was correct.

What is the theory?
Retinex says that, rather than measuring, what's first important to you is the name of the colour, and being consistently independent of what colour light is illuminating a scene. So if you're seeing a tiger at sunset or a tiger under a green forest canopy, you want it to still look orange even though the light that's hitting your eye may be a completely different colour depending on what the illuminating light is like. And his Retinex theory said that your brain compared images of the three different channels — the red, green and blue senses in your retina — and, from that, looking at the relative brightness, it figured out what the correct colour name was and that's what you saw.

Depending on the brightness?
Well, by comparing the brightness. For instance, with your green senses in your retina, a piece of orange paper looks dark, while a piece of green paper looks bright. By comparing the two, your brain figures out what the correct colour should be. That's why, for instance, if you take slide pictures under fluorescence, incandescent [light] or daylight, the pictures would be orange or green or blue or normal, depending on the colour of light. At the same time, to your eye, everything looks consistently the same colour. Land's theory was about how colours look consistently the same, pretty much irrespective of what colour light is illuminating.

Read this

Photos: Tech for colour blindness and night vision

Tenebraex has captured attention for its technology that brings a range of colours to monochromatic night-vision goggles...

They stopped teaching his theory in school because he was just a businessman. We [Jones and Purcell] always thought he was correct. Four-plus years ago we figured, whatever the inspiration comes from, this conceptual framework might allow us to just figure out a way of making a practical four-colour night-vision system. And for our colour night-vision system, we figured out a way to make your brain see all of the colours while using only two channels, not three, which most people say you can't do.

You know, at conferences I'll say: "Well, we're working with the Retinex theory" and, you know, people go: "Ha, ha, ha; he was just a businessman. He wasn't a real scientist". Well, he was one of the smartest people in the last century and we think his theory was right. And if his theory wasn't right, you would not see colour when you looked through our device.

Can you explain that?
Most people think you need red, green and blue (RGB) or cyan, magenta and yellow (CMYK) in order to render all of the colours. But that's not true. You can do it with two dimensions. I don't know if you've ever seen a colour diagram that has all the colours of the spectrum, but you can see all the colours by rendering it on a two-dimensional graph. What you need a third dimension for is so you can see, say, dark red versus light red, or dark blue versus light red. The vertical access is only for brightness.

Are the ColorPath colour night-vision goggles and the eyePilot software for the colour-blind born out of the same technology?
It's in the same researching way of thinking about the problem, because then we said "You know, I don't know where this thought came from". But one way of describing a colour-blind man, and most people who are colour-blind are men...