... and The Pitfalls of Relying on Screen Size and Resolution to Improve Accessibility.
By knowing a little about how screens work and Windows displays itself you can make better decisions as to the best practices in making your computer more visually accessible. This article has been over-simplified to avoid too much lengthy technical boring stuff.
There are generally two types of screen available: Cathode Ray Tube (CRT) and Thin Film Transistor (TFT, a type of LCD).
CRT – have a large back like a traditional telly
TFT – have a very narrow ‘footprint’
The advantages of the TFT screens are numerous and they are becoming very popular. Not only are they small and convenient, their virtually-flicker free technology eliminates many headaches and nausea associated with using a PC for prolonged periods. This also makes them a much safer option for those who have photosensitive epilepsy. The drawback of these screens is that apart from their cost, which is thankfully coming down all the time, is that their 'resolution' can't be changed.
A computer screen is essentially a grid like a sheet of maths paper, made up of millions of tiny boxes known as pixels. When the computer wants to display something on the screen it sends out the co-ordinates of the square in the grid and what colour it wants it to be.
In this grid the screen isn't displaying anything - so all the cells (or pixels) are black. If the screen isn't sent information for a particular pixel then it will display it as black, as it does when the computer is off.
In this grid the computer has had a half-hearted attempt at drawing a smiley face. It would have done this by sending to the screen the following sort of information:
C2 = BROWN; E2 = BROWN; G2 = BROWN; D3 = BROWN; F = BROWN; D5 = WHITE; etc.
The resolution of a screen is the number of cells in the grid. Your screen is likely to have a resolution of around 1024 pixels across by 768 down, this currently being the most common.
If you have a CRT screen then the resolution isn't fixed: you can step up and down within a certain limit, without even needing the restart the computer. Setting the resolution lower, say to 800 by 600, causes fewer pixels in the same physical area. Consequently they stretch to fill the space and everything gets much bigger in a very straightforward manner. Compare the image on the left (800x600) to the image in the box above (1024x768) and you can see what a powerful tool changing the resolution can be. This is a foolproof way of enlarging everything on the screen (except most modern games which define their own resolution).
Unfortunately TFT users don't have this ability. TFT screens have a 'native' resolution that is defined when they are built in the factory and any change in the resolution leads to a degree of blurring which most users find intolerable. A solution to this problem may come in the form of Resolution Independence (see below).
Buying a bigger screen is a very simple and effective way of enlarging everything on the computer ALthough it may not seem like much on paper the difference between a 15" screen and a 19" is quite impressive.
15" Screen at 1024 x 768
19" Screen at 1024 x 768.
Increasing pixel densities on modern, larger TFT screens can actually result in a smaller image than on an older, smaller screen.
An older 15” flat screen that you are currently using might have a native resolution of 1024 x 768.
The brand new 19” model you're thinking of getting might display using a resolution of 1600 x 1200 or higher.
The pixels are more densely packed on the 19" model and each pixel is smaller than those on the 15" screen.
Even though the 19" overall screen area is significantly larger, any text and images shown on this screen will actually appear slightly smaller than on the older screen.
Resolution Independence is a very new development that is included with Windows Vista and OS X Leopard. Essentially it removes the relationship between objects on the screen and the pixel grid, allowing those objects to be resized with distortion of blurring... [more: resolution independence]
Well if I were you I'd read about How Windows Displays Itself using GUI Widgets and how these are affected by Items.
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