Java Glossary : resolution

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resolution

The fineness of the monitor screen.

If you look at the Windows control panel under Display, (or the equivalent) you can see that you can control the screen resolution, typically something like 640x480, 800x600, 1024x768, 1280x1024 or 1920x1200. The image on your screen in made up of rows and columns of tiny coloured dots called pixels. The number 1280x1024 means the image is 1280 columns of dots wide by 1024 rows of dots high.

Low resolution would be 640x480 pixels (width x height). High resolution would be 1280x1024. The Dell 15" WUXGA has 1920x1200. Because the more dots you have, the smaller they are, you must compensate by using a larger monitor for high resolution, or the type will be too small to read.

If you double the resolution, there are four times as many dots. This means the video hardware has four times as much work to do each second to keep the screen refreshed. Further, the computer has four times as many dots to render each time the screen changes. For high resolutions, you thus need high performance video hardware.

Recent LCDs use a hardware resolution between 86dpi and 147dpi, only a few LCDs use a resolution around 204dpi (Toshiba, IBM).

The problem is ordinary Java apps look too small on these high resolution screens, because Java apps are constructed in pixels, not points or inches the way PostScript is. A program that draws an icon 32 pixels high looks huge on a low res screen, but shrinks down to a mite on an ultra highres screen.

The free and open source JGoodies Forms layout system addresses this issue; it support non-pixel sizes: pt, mm, cm, in and more important, it supports dialog units (dlu) that scale with the resolution and dialog font size.

Measuring Resolution

To summarise, there are four way to measure resolotion:

total number of pixels (dots), e.g. 1280x1024. Bigger is better.
diagonal size of the screen, e.g. 15" (LCD makers are more honest that CRT makers). Bigger is better.
dpi, dots per inch, how densely the pixels are packed. Bigger is better. A 1280 x 1024 image on a 17" monitor is only about 100 dpi. A 1600 x 1200 image on a 19" monitor is about 111 dpi.
dot pitch, how wide the physical sub-pixels are. Smaller in better. A typical monitor spaces the red dots about 0.231 mm apart.

Trust your eyes not the specs. They are the ones that have to be happy with the image. It should not flicker or distort. It should be sharp and clear.

Printed Resolution

An old HP Laserjet printer is 300 dpi.
Newsprint is about 500 dpi.
A modern laser printer is usually 600 dpi.
Modern inkjet printers are about 4800 x 1200 dpi. They are limited mainly by ink smudging and the quality of the paper.
Glossy magazines and photypesetters are about 1200 dpi.

Discussion of Scaling Problem ¤ JGoodies Forms layout system ¤ monitor ¤ pixel ¤ review of JGoodies

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