Hardware Reference
In-Depth Information
Pixels
In a color monitor, each picture element (pixel) consists of three red, green, and blue
(RGB) subpixels. By varying the intensity of each of the subpixels, you can cause the
overall color and brightness of the pixel to be anything from black (all off) to white (all
on) and almost any color or level in between. The physical geometry of the RGB sub-
pixelsvariesdependingonthetypeofdisplay,buttheshapeisnormallyeitherrectangular
stripesorrounddots.LCDmonitorsnormallyhavethethreesubpixelsarrangedasrectan-
gular vertical stripes in a linear repeating arrangement. CRTs may also use linear stripes,
or they can have staggered stripes or dot triads.
Whenyou'rechoosingadisplay,themostimportantconsiderationsarethecombinationof
size and resolution. The overall combination of size and resolution is normally expressed
in pixels per inch (ppi), but it can also be expressed in pixel pitch, which is the distance
betweenpixelsinmillimeters.Ahigherppinumber(orlowerpixelpitch)meansthatfixed
size images such as icons and text will be smaller and possibly harder to read. Pixel pitch
is also sometimes called
dot pitch
, in reference to the dot-shaped subpixels used on some
displays.
For a given size screen, higher resolution displays have a higher ppi number, which cor-
respondstoalowerpixelpitchnumber.Asaresult,thepictureelementsareclosertogeth-
er, producing a sharper picture onscreen. Conversely, screens with a lower ppi number
(which equals a larger pixel/dot pitch) tend to produce images that are more grainy and
less clear.
Figure 12.18
illustrates a dot-shaped subpixel arrangement most commonly found on
shadow-mask base CRTs, where the pixel or dot pitch is the shortest distance between
same-color subpixels.
Figure 12.18
Dot-shaped subpixels, where pixel or dot pitch is the shortest distance between same color
subpixels.
