[Barrykgerdes]

Hi
I am not an expert on displays but there are a number of different ways of displaying information on a screen to excite the eye to a respose. I will just look at two types The LCD and the LED screen.

The LCD screen uses a matrix of three filters arranged as three "stripes" of colour filters arranged in a square. This forms one pixel. Put a magnifying glass to the screen and you will see this formation. These filters allow a measured amount of light of each of the primary colours to pass through according to the digitised amount of each colour, illuminated from behind by a white electro lumescent screen. I am not sure of this I think LCD uses CMY as the colours because they filter and LED wil use RGB because they emit but it could be the other way around.

The LED screen emits light in the three colours in the same way but each LED is its own source of light of which the intensity is controlled by the digitised control signal as before.

The eye of course perceives these tri colour spots as a single colour which has as many different tones as the bits of the digitised signal allow.

When you are observing a spectum of a star for instance the actual colour of the various sections will depend mainly on how your screen is set up. The aim here is not the actual perceived colour but the position and number of dark lines that appear on the spectrum corresponding to the absorption spectra of the elements in that star that define its construction and its relative speed.

Barry