Resolution, scanning, and graphics size is a vast and often confusing topic, even for experienced designers. For those new to desktop publishing it can be overwhelming. Before you panic at the thought of what you don't know about resolution, focus on what you do know and some basic, easy to understand facts.

Firstly resolution is the measurement of how many dots/pixels fit in to one inch. It is measured in dots per inch (DPI), this is likely to be a term you’ve heard of before. Equally you are likely to know that the higher the resolution, the sharper the image will be and the lower resolution the more the images appear fuzzy blurred and jagged.

In more detail:

This is easy to explain, for example an image sized at 20cm x 20cm has a resolution of 300 DPI. If this is enlarged to 40cm x 40 cm its resolution halves to 150 DPI as the dots are stretched over a larger distance. If the image is made smaller, from 20cm x 20cm to 10cm x 10cm the resolution will increase to 600 DPI as the dots are compressed into a smaller space.

When an image is of a low resolution it is difficult to increase it. Resolution can only be effectively increased, as previously described by decreasing the images size, this maintains the images clarity. Equally recapturing the image at a higher quality setting will improve resolution. Another less effective option is upsampling where a low resolution image is saved to a higher resolution with no changes to dimension size. This adds more dots per inch but cause the image to become blurry.

So what is the right resolution?

The answer to this depends on what the image is being used for:

• For sole use on screens/monitors

Images and text on a screen or monitor require a lower resolution than when printed due to the use of RGB colour mode (see CMYK/RGB article for more info), this allows quick transmission when on the internet. Pictures on the Web are usually 96 or 72 DPI because that is the resolution of most computer monitors. If you print a 72 DPI picture to printer, it won't usually look as good as it does on the computer monitor. This is because the printer doesn't have enough dots of information to create a clear, sharp image.

Sites can also be optimised to look their best on all types of screen. Using a setting of 1024x768 DPI most screens will produce a good visual from low end to high end screens.

• Typical Images and plain designs for Printing

There are colour dots and there are black dots. In black & white printing, the size and shape of the black dots and how close or far apart they are printed creates the illusion of shades of gray. Generally the more dots, or higher the DPI that is used the clearer the picture being printed, but a photograph scanned at both 300 DPI and at 600 DPI will look the same printed on a 300 DPI laser printer. The extra dots of information are "thrown out" by the printer but the 600 DPI picture will have a larger file size. This is important to remember when going to print as your image quality is likely to alter.

For general printing a typically recommended resolution is 300 DPI.

• More Intricate Images, for example, images with text.

In this case higher resolutions would be recommended if a printer with the capacity to print higher resolutions is available. Use of a higher resolution will produce a crisp and clearer image and firm up differences between the text and the images, easing the ability to read the literature. For this type of printing a resolution of 400 DPI is recommended.