EIA TEB27-1988

INTRODUCTION

A great deal of confusion exists about the precise meaning of
the terms Resolution and Addressability as
applied to display systems, Additionally, once clarity of meaning
is achieved, the problem remains of designing a system in which
these two quantities are properly related to each other to maximize
the quality of the displayed image. Such a relationship is one in
which the image meets some perceptual cfiterion of image quality.
This paper, then, is concerned with clarifying the meaning and
specification of resolution and addressability in Cathode-Ray Tube
(CRT) based display systems arid with presenting a visually derived
metric for selection of the optimal relationship of resolution and
addressability .

In essence, resolution is a property of the design of the
display device. It is derived from the width of a line or spot
imaged on the screen: The narrower the line or the smaller the
spot, the higher the resolution. From the measured line width,
resolution can be specified in a number of ways, such as lines per
unit distance, Modulation Transfer Function (MTF), spot size, etc.
We will consider the line width at 50% of the maximum luminance
intensity, since simple conversions exist to translate the various
metrics of resolution [1],[2].

Addressability is a characteristic of the display controller and
represents the ability to select and activate a specific point of
x,y coordinate on the screen. On rastered displays, this
is usually stated in terms of the number of lines scanned from the
top to the bottom of the display screen as well as the number of
points along each raster line.

Since addressability is controiled by the hardware driving the
CRT, and since resolution is determined by the design of the CRT,
these two display characteristics are independent of one another,
However, to obtain high levels of image quality, certain relations
need to be maintained between resolution and addressability. For
example, if resolution is too low (large spot sizes), successive
lines will over-write preceding lines. Under some conditions, this
may produce image artifacts such as false contours. Conversely, if
addressability is too low (large spot separations), then adjacent
raster lines will not merge and they will appear as visible
stripes.