Colors of the world

We see our world in colors. That's very natural. It is so integral part of our world that we could not imagine a world without colors. When I was a kid my father took a lot of black and white photographs with his camera. I asked him that why do they look like that, with no colors and all. He explained that the color photographs require more complicated technology than black and white. The answer did not satisfy me - I claimed that wouldn't it be more simple to picture the world as it is rather than to filter some very carefully selected colors (like red, green, yellow and so on) of the picture out and leave some (like black and white) untouched. To me it seemed that it would require more advanced technology. i don't remember if my father could answer anything to that. Maybe I was a difficult kid with all my questions.

The true color of an item is actually a function of amplitude that it reflects for different frequencies of white light. White light of course is something that has an equal amount of all frequencies of light. The amount of different variations and combinations of colors is endless!


How does then human eye perceive color? The retina inside human eye has dedicated cells to react in three different wavelengths. Only three. This means that of all the different wavelengths most are totally ignored, or they are observed as combinations of colors. For instance if there is an object that reflects light at 500 nm wavelength, we most likely observe the object being cyan. However, we also observe the combination of blue and green lights as cyan color. With our eyes, we just can't see the difference.

The above leaves one question open: why? Why do we recognize some frequencies of light so well and some roughly? There must be a reason, and the reason must be in human evolutic history.

For evolution in general, it must have been quite important to distinguish green leaves from blue sky and water, to be able to navigate and move quickly, and to be able to find water. Originally it must have been a great asset in both hunting and escaping hunters. I imagine this skill must have developed quite early, after life moved from sea to land.

What about red then? What could have been the driving force to make us observe red light? When did that happen? Which animals are capable of observing red anyway? (For instance bulls do not, which means the matador's equipment could be practically any color, causing an equal effect.) Maybe red color has come to enhance the seeing capabilities, because most of the colors you find in nature (plants, rocks, sand, dirt) are in this specific area, so to be able to observe your surroundings it was very useful to recognise the frequency of the color more specifically, Now it was able to recognise for instance brown rock from green grass, and see where to go next.

The fact that human can observe three colors also lead to technical decisions: all video and image formats, television and camera hardware, transmission protocols etc. they are all based on the assumption that vision is composite of three colors. And this is the case when we talk about humans. Imagine that an alien race would come to earth that has a similar vision but perceives more colors, or colors of different wavelengts than us. They could not watch TV or movies, use our computer monitors, see color prints, or even those old-fashioned photographs properly!