Television sets and video monitors rely on tricking the visual system into believing it is seeing the full range of possible colors. In reality, they are only generating approximations of the light that would actually enter the eye if we were looking at a real object.
The problem is this: the visible spectrum actually consists of an infinite number of possible light wavelengths in the range from 380 to 700 nm; light waves from across that range enter the eye and are capable of activating photoreceptors within the eye: this corresponds to the wide range of colors we can perceive.
But TVs and other electronic displays generally only use three different wavelengths of light — red, green, and blue. These colors are mixed in varying proportions to create all the other colors we see. But with just these three colors, only a small portion of visible light wavelengths can be approximated (the diagram on the left, taken from Wikipedia, gives you some sense of the disparity: the colored triangle represents the colors a TV can produce, while the gray arc represents all visible colors).
Particularly relevant for CogDaily readers is the fact that the human eye uses a similar trick to perceive light: there are only three (and sometimes four) different photoreceptors in the eye. Each one is activated by a certain set of wavelengths. The brain combines the information from each photoreceptor to rebuild a picture of the color. Why is the eye better than a TV monitor? Because each photoreceptor is activated by a range of wavelengths, while TV pixels can only display one color at a time.
This is where the new video technology comes in to play. The BBC is reporting on a Swiss laboratory which has developed a TV monitor which can display any wavelength from each pixel. The display uses 400 diffraction gratings — striped membranes which work like a prisms — to create the colors. Each grating can be independently adjusted to produce any color in the visible spectrum. While 400 pixels isn’t enough to display a full picture (the best displays use millions of pixels), the researchers claim that the process can be inexpensively scaled up to full size.
What will be the impact of this new technology?
First off, truer, more realistic colors. The researchers say no current monitor can display a truly blue sky, so pictures will be more realistic. For scientists, there is also the prospect of clearer images in electronic microscopes and telescopes.