The retinas of our eyes are equipped with two types of light-sensitive cells -
rods and cones. The rod cells are sensitive to all wavelengths, and detect overall light
intensity. The cone cells come in three varieties, each of which respond to a separate band
of wavelengths which we call the red, green and blue segments of the spectrum. When
each type of cone cell is saturated we see 'white' light. TV
screens and computer monitors work on the same principle, having three types of
phosphorescent pixels emitting red, green and blue light respectively.
By convention, colour intensity is defined on a scale of 0 - 255, or 00 - FF in hexadecimal
notation. By clicking on the red, green and blue bars below you can change the individual
components for the background colour of this paragraph. The hexadecimal code passed to the
computer to display this colour is also shown. Have fun!
(Note 1: - users of Netscape 6 should turn off the sidebar to avoid errors)
(Note 2: - Linux users may find the accuracy of the color bars to be 4-5 pixels out}