Scanner is an input devices that convert text document or images into softcopy that can be manipulated into the computer. They scan hardcopy of either text or images to convert them mostly into digital images. They use light sensor to do the scanning.

The main function of scanner is to convert images and documents into digital form that can be processed by the computer or other digital devices.

Types of scanner

Scanner can be classified into 2 categories:

  1. Handheld scanners

The user holds the scanner and passes it along the document or image that they are scanning. It should be move slowly to capture all the details and to get the best quality. They are portable, cheaper than flatbed and they are mostly met for home use or scanning of small documents.

handheld scanner

  1. Flatbed scanners

Instead of user holding the document on their hand, the document is placed on the scanner just like a photocopier then the scanner moves the light along the document to scan. They are bigger in size than handheld, more expensive but they can scan larger document and the user is less involved.

flatbed scanner

How scanner works

First the user put the document to be scanned on the right place on the scanner. The scanner passes light along the document like in a photocopier machine. The light is the reflected to a light sensor which determine how much light is reflected from each point.

Blank spaces are brighter than those with content which means they reflect back more light back. The sensor converts this into light electrical signals which are then converted into digital for computer. If the scanner is to capture coloured document the signals are passed to the colour filter so as to get the appropriate colours.

Factor to consider when selecting a scanner

  • Type of scanner

Depending with the work you intend to do with the scanner you should choose one that will meet your needs. If you intend to scan larger document and frequently then flatbed is the best.

  • Quality of scan

Different scanners come with different number of pixel that they can be able to capture. For a clear scan select one with high resolution, one that can capture more pixel per inch. Again flatbed is more likely to give one a good quality scan than handheld. High quality means it requires more storage space on the hard disk.

  • Cost

Another factor is cost. You cannot buy what you cannot afford, so check you budget before going for a scanner. Remember not to compromise the quality by going for something that is cheap which may not met your needs.

  • Portability

If your work involves moving around them it would be appropriate to get a handheld because it more easy to carry around

  • Colour or No colour

Depending on what you want you can consider getting a scanner that can give you black and white only or one that can give you coloured image. It better to get a coloured one because, they mostly come with the other option of black and white in the setup which you can change.