What is worth doing is worth the trouble of 
asking someone to do.

Concept 2.1 : The RGBA Display Mode
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Idea:
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OpenGL provides two different types of color display 
modes.  These are the RGBA mode and the ColorIndex mode.  

In RGBA mode, the hardware sets aside a certain number 
of bitplanes for each of the R,G,B, and A components.  
The R,G, and B values are typically stored as integers 
rather than floating point numbers and they are scaled to
the number of available bits for storage and retrieval.  
For example if a systems has 8 bits available for the R 
component, integers between 0 and 255 can be stored: 
thus 0, 1, 2, ..., 255 in the bitplanes would correspond 
to (R)ed values of 0/255=0.0, 1/255, 2/255, ..., 255/255=1.0.  
The main point being that regardless of the number of 
bitplanes 0.0, specifies the minimum intensity and the 1.0 
specifies the maximum intensity.  

The Alpha value the A in RGBA has no direct effect 
on the color displayed on the screen.  It can be used
for many things, including blending and transparency 
(Chap 6).

Dithering
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Dithering is the technique of using combinations of
some colors to create the effect of other colors.  i.e.
it is a method for graphics hardware to increase the 
number of apparent colors.  Suppose your system has only 1 
bit each for R,G, and B and thus can display only eight 
colors: black, white, red, blue, green , yellow, cyan, and 
magenta.  To display a pink region, the hardware can fill 
the region in a checkerboard manner, alternating red and 
white pixels.  If the eye is far enouugh away from the 
screen, that it cant distinguish individual pixels, the 
region apears pink.  

You enable or disable dithering by passing GL_DITHER to
glEnable() or glDisable().  Note that dithering, unlike 
many other features is enabled by defualt.