Advantage:

• Scanners can convert photographs and flat documents into electronic images.
• Both colour and black & white images can be created.
• Extremely high resolution if required.
• Relatively inexpensive compared to a digital camera.

Disadvantages:

• Cannot take 3 dimensional images.
• Document has to fit on the glass
• Relatively slow compared to taking a digital photograph.

The scanner is used to input graphic information into the computer.

Description: The picture to be input is laid flat, face down on the surface of the scanner and the lid lowered to avoid stray light creeping in.

The scanner sweeps its sensors along the picture. As it does so, an image is built up as a series of 'pixels'. Each pixel represents a tiny part of the picture.

A scanner can

1) Create a black and white image. - handy for line drawings and text.

2) Create a full colour image - excellent for inputting photographs.

The number of pixels can be adjusted to suit the image being taken. For example if a small file is required, then a low-resolution (75 dots per inch) black and white image may be adequate. This will result in an A4 sized image being only a few hundred kilobytes at most.

On the other hand if the highest quality is required then a high resolution (300 dots per inch+) full colour image is taken. This will result in a huge file, easily several Megabytes in size.