Creating Video

You are here : HomeDigital ImagingSource and Store Graphics

factfile3.10 Scanners


Like a digital camera a scanner is also an image capture device. It captures images, digitises them and feeds them into a computer. The object to be scanned is placed face down on the glass plate of the scanner. A lamp fixed on the scan head illuminates the object as it moves across it. An angled mirror that is also fixed on the scan head bounces the reflected image through a lens onto a Charge-Coupled Device (CCD), or image sensor like the one in your digital camera or camcorder.

The quality of a scanner is determined by the number of samples that its sensor can take in one inch (SPI). The data is then directed through an Analogue-Digital Converter (ADC). This digitises it, as the name suggests. Finally, your computer needs a driver, or special software to interpret the data. This is called a TWAIN driver. For a detailed, illustrated account of how scanners visit:

Analogue Digital

Did you know? There are conflicting explanations for the origin of the term TWAIN. Some people argue that it stands for "Technology Without An Interesting Name". Others believe it quotes a poem by Rudyard Kipling called "The Ballad of East and West", in which the poet writes " … and never the twain shall meet …" (twain = two), the explanation being that in the early days of computing it was difficult to connect scanners successfully to personal computers (i.e. "never the twain shall meet"). What do you think?

Previous PageMain Site Indexsection indexNext page