Light sensors that can detect and report actual colours are on the market, however they're not that inexpensive. An interesting alternative is always to make your own, and by following the project documented by George Gardner you can possibly create your own colour sensor. George's version uses an RGB LED and a photoresistor (light sensor).
The red, green then blue LEDs are rapidly illuminated in order and held against the object (with the sensor) whose colour you wish to detect. The amount of light reflected from each primary colour helps determine the colour of the object, and with some experimenting and calibration a reasonable result can be made. This is demonstrated in the following video:
An interesting use of the properties of light and inexpensive hardware - visit George's website to learn how it's done. And for more, we're on twitter and Google+, so follow us for news and product updates as well.
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