If there are false-color images, does it follow that there are "true-color" images as well? And if so, what are they? You already know half the answer: a true-color image (think photographs from last Christmas here) is the kind of color photo we're all used to. Greens are green (that Yule tree for instance), reds are red (Santa's suit), and so on. We usually see the world in what we think of as true color. (Bugs, birds, and other critters have a different view of true color, but that's another story!)

Well, that was easy. But what about this false-color stuff? Very simply, if we substitute, say, red for green, blue for red, and so on, the resulting image will not be a true representation of the way we humans see things. Therefore, the colors are false, or pseudo-color. Is it really that simple? Yep!

[True-color image of Charleston, SC][False-color image of Charleston, SC]

But why in the world would we want to do such a thing?

As we noted above, the human eye can see a whole lot more detail in color images than in black and white. It is also true that if we are looking at an image in which the colors aren't what we expect, we may actually see a lot more detail. But there is an even bigger reason: we can look at details in areas of the electromagnetic spectrum where the human eye is not very efficient, like in the infrared region.

[visible spectrum image]

Therefore, by using electronic detectors, films, or photographic filters that are sensitive to certain regions of light in the electromagnetic spectrum, and by displaying the results in false colors, we can learn a lot more about our environment.

So the next time you hear "Roses are red, Violets are blue..." you can say, "But in a false-color image, that may not be true!"



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