INTRODUCTION
A great deal of confusion exists about the precise meaning ofthe terms Resolution and Addressability asapplied to display systems, Additionally, once clarity of meaningis achieved, the problem remains of designing a system in whichthese two quantities are properly related to each other to maximizethe quality of the displayed image. Such a relationship is one inwhich the image meets some perceptual cfiterion of image quality.This paper, then, is concerned with clarifying the meaning andspecification of resolution and addressability in Cathode-Ray Tube(CRT) based display systems arid with presenting a visually derivedmetric for selection of the optimal relationship of resolution andaddressability .
In essence, resolution is a property of the design of thedisplay device. It is derived from the width of a line or spotimaged on the screen: The narrower the line or the smaller thespot, the higher the resolution. From the measured line width,resolution can be specified in a number of ways, such as lines perunit distance, Modulation Transfer Function (MTF), spot size, etc.We will consider the line width at 50% of the maximum luminanceintensity, since simple conversions exist to translate the variousmetrics of resolution [1],[2].
Addressability is a characteristic of the display controller andrepresents the ability to select and activate a specific point ofx,y coordinate on the screen. On rastered displays, thisis usually stated in terms of the number of lines scanned from thetop to the bottom of the display screen as well as the number ofpoints along each raster line.
Since addressability is controiled by the hardware driving theCRT, 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 relationsneed to be maintained between resolution and addressability. Forexample, if resolution is too low (large spot sizes), successivelines will over-write preceding lines. Under some conditions, thismay produce image artifacts such as false contours. Conversely, ifaddressability is too low (large spot separations), then adjacentraster lines will not merge and they will appear as visiblestripes.
- Edition:
- 88
- Published:
- 09/01/1988
- Number of Pages:
- 9
- File Size:
- 0 files
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