Graphics Workshop - Scanners

By integrating digital technology it has been possible to produce cameras that don´t use film and therefore don´t need developing, you also gain the advantage of being able to select which pictures you want to keep and those that you want to delete.

This week we cover another popular area of image capture, that of scanners. To put it simply, a flatbed scanner is very much like a photocopier. Instead of printing the image, however, the signals it receives from bouncing a light source off the picture are sent straight to a computer for manipulation.

In previous years there would be scope in this article to write about the many different styles of scanners in addition to the fore-mentioned flatbed scanner. These include scanners that were handheld (you held the scanner and passed it manually over the document) and those that were sheet-fed (you fed the document into the scanner, like with a fax machine). Luckily, these machines are becoming very much obsolete in these days of truly affordable flatbed scanners.

Many of the same factors need to be taken into account when choosing the correct scanner for you as those considered when purchasing a digital camera as explained last week. These include the following:

1) Resolution and Colour Depth - These really are the two most important factors when choosing a scanner. The Colour Depth defines the number of colours that the scanner is successfully able to distinguish. The optical resolution is a measure of the overall definition of the picture; an example of resolution could be that if quoted a maximum resolution of 600dpi, the scanner can pick up 600 individual dots per every inch of the paper.

Scanner manufacturers also sometimes quote figures in terms of Interlaced Resolution - This is a measure of how accurately the scanner can fill in the gaps between the little dots. For example, a scanner of 600dpi may be able to up its resolution to 2,400dpi by intelligently `guessing´ what the other 1,800dpi should look like. Obviously it is best to have a scanner that produces high resolution pictures without the guess work so shy away from Interlaced Resolution claims as a sole basis for choosing a particular model of scanner.
The colour depth and resolution that you require can only be decided yourselves by considering what purposes you will be using your scanner for. For most users however I would recommend at least 600 x 1,200dpi and 36-bit colour as a general guideline.
2) Interface and software - The speed of the Interface between your scanner and the computer determines how fast it can transfer the picture or document across from one device to the other. Typically, USB is the best choice at the moment as it is a cheap, reasonably fast interface. Interfaces also available include those that transfer the data through your printer port (LPT) or via a high speed technology known as SCSI which will require a special card to be fitted inside your computer. Check to see that the scanner comes with all software needed for scanning and editing the documents you scan and that your computer is compatible with whichever interface you choose.
3) Price - Obviously an important aspect for any user, flatbed scanners now start off at around £60 from mail order dealers such as Dabs
There are further features that I haven´t yet mentioned of modern day scanners. Most have software included to turn them into fax machines (via a modem in your computer), the ability to become a photocopier (prints straight to the printer without any further prompting on the computer) and a many now also use a technology known as OCR (Optical Character Recognition). This technology is used for those who may want to change a document that they have on a sheet of paper but don´t want to have the worry of typing it all out into the computer. By using OCR, it is possible to scan the document and the software will recognise words on the scan and put it straight into a Word Processor such as Microsoft Word where it can be edited like any other file.

Except for these considerations, just be wary and weigh up each individual scanner, listing the pros and cons of each one that you look at. You will find that there is a surprising amount of variation between the different brands and models of scanners and without looking thoroughly, you may pay a high price for a scanner that is laden with features that you will never use.

Computer Articles 2007