Monitor

This image shows the relative sizes of different resolutions.

The resolution of a screen is the number of 'pixels'(px) that make up its image. Pixels are small coloured dots that together create a full colour picture. There are usually millions of pixels in a screen and the more you have, the more can be displayed at once. Resolution will be written as the number of pixels in the horizontal direction by those in the vertical direction, e.g. 1600x1050 would mean 1600 pixels wide by 1050 pixels high.

One way to explain the difference a higher resolution screen would make is to imagine you bought a larger desk for your office. The things on the desk never change size, an A4 piece of paper will still be A4, a larger desk will simply mean you can now fit more A4 pages on your desk, or blow them up to A3 and still have as many visible at once. Items on your computer desktop will always use the same amount of pixels, so a window that is 300px wide on a 1024x768 screen will still be 300px on a 1900x1200 screen, there would just be more space around it. A larger screen with the same resolution would not give you any more space, it would simply enlarge the image by having larger pixels.

For gaming, having a higher resolution screen means that your games can run with more detail, having a higher number of pixels to draw the same image. However the higher the resolution, the more powerful the graphics card needs to be to maintain the same frame rate.

This image shows the relative sizes of different monitor screens.

The size of a monitor is measured in inches and denotes the diagonal size of the screen. Most monitors these days are 'widescreen' which means they have a wider screen size, usually in a 16:10 ratio (16 units wide and 10 units high). This differs from wide screen TVs which have a 16:9 ratio.

Having a larger monitor will mean you can support higher resolutions, which will give you more 'space'. It may also give you a larger picture than a smaller screen with the same resolution

This is only really important for fast gaming and fast action in videos. A slow response time can result in a blurry image when something on the screen moves very fast. These days this is less of a problem, as most new screens respond in less than 10ms which is enough for the problem to almost disappear in general use. If you will be gaming or watching action movies look for 5ms or less.

Contrast ratio denotes the amount of contrast that can be achieved on the screen. This is measured by comparing the darkest image the screen can achieve with its lightest. So a contrast ratio of 1000:1 means that the white is 1000 times brighter than the darkest image. Low contrast ratios (< 400:1) can result in washed out images. No monitor currently available can give an absolute black image (which would be infinity:1), though some are much better than others.

Some screens use what is called a 'dynamic' contrast ratio, which darkens the light inside the monitor darken the darkest colour if a particular image is very dark. This can be effective in certain conditions (such as a dark scene in a movie), but can also be misleading as a dynamic ratio of 8000:1 can still only give a ratio of 1000:1 at any one time. For most general use 1000:1 will be sufficient to give a good depth of black colours.

The brightness of a screen is the amount of light it can output from a given area, in most cases 1 m squared. This is an estimated value as very few screens are actually big enough to have an area of 1 m2. The brighter the screen the more you will be able to see in a bright room, for example if the sun is shining. A value of between 300 and 500cd/m2 is a good starting point for most users.

The amount of colours a monitor can display is called its colour depth. This is measured in the amount of information per red green and blue channel the monitor can display. Most common monitors use either 6bit or 8bits of information per channel giving a total depth of 18bit and 24bit respectively. An 18 bit monitor can display a total of 262,000 colours, while an 8bit can display 16.7million. The difference between these monitors is noticeable, so manufacturers use a system called 'dithering' on 6bit monitors to trick the human eye into seeing many more colours, some manufacturers even claim to display 16.7 million colours on 6bit panels. For most users 6bit with good dithering is more than adequate, but for those looking to do professional graphic or photo work should look at 8bit monitors.

It can be difficult to know whether a screen is 8 or 6 bit as most manufacturers do not mention this in the specification. If the number of colours is quoted as less than 16.7m (e.g. 16.2m) then it will certainly be a 6bit screen. If it is quoted as 16.7 million colours, but does not mention either 8bit or 24bit then it's almost certainly a 6bit screen.

However sometimes manufacturers will say 16.7m (24bit) when in actual fact they are using 6bit screens. In this case it can be almost impossible to know for sure without contacting the manufacturer directly, but there are usually 2 tell tale signs. The first is price, as 8bit panels are considerably more expensive than 6bit. Second is response time as 8bit panels have slower response times than their 6 bit counterparts.

For example Apple Cinema screens are all 8bit, with a 23" version having a response time of 13ms and costing in the region of £600. By comparison an Iiyama 6bit 24" screen with a 2ms response time is just £260.

Ultimately the best way to find out details on a monitors image quality is to read reviews of it. Google the monitors model number + ‘review‘ and you should find a fair few reviews which should tell you weather it is 6 or 8bit.

Some monitors will come with inbuilt accessories, such as speakers or USB hubs. Depending on your situation these may or may not be useful. Be aware that speakers on monitors are usually very low quality and should not be considered for anything but the most basic use.