The world of computing has come a long way since the days of green-on-black screens and block graphics. Today nearly all modern computers have the ability to display photographic quality images and graphics.

While some users will simply want to enjoy the work of others, others still will want to create their own digital image collection. However to do so requires either a digital camera (that records directly in digital format) or a scanner - that translates a set picture image in to the necessary digital form.

Naturally you don't have to actually buy a scanner or digital camera most major towns have buros and services that will perform a digitizing service for you. Kodak (and others) will even burn your photos on a CD for you mail order. However, as we shall explore today, the world of scanners goes beyond simple digital imagery and into the world of copying and faxing - see outbox for extra details.

There are three major categories of scanner: The first is the handheld scanner that is held in the hand and physically dragged across the target image. The second is a flatbed scanner - that looks more like a small photocopier and requires the image to be laid on a glass/plastic plate. And lastly is the more expensive "slide and negative" scanner that works - as the name suggests - by having a slide or negative inserted in its front slot.

Handscanners have faded from popularity and are only rarely glimpsed in modern advertising. Nevertheless they still do work and are very portable - if this is important in your situation. Curiously a new type of handscanner is becoming available that picks text from foreign newspapers (and the like) and translates it to english!

To complicate matters further, there are a set of office computer devices that sometimes go by the name of all-in-ones. These are a combination of colour printer, copier, scanner - and often colour FAX. Hewlett-Packard have reported that these packages are beginning to take off in small business circles.

All scanning requires an image to be passed over a photo-sensitive beam (or "head") that records, in most cases, the primary (red, green, blue) colours. Many also have ability to record in greyscale.

These "scanheads" are often bought-in from third party manufacturers so it is not uncommon to have them appear in more than one make or model. However the quality of the support software can play a role in convenience and image quality.

Scanners are one of those peripherals that feature moving parts. While these will always make some noise, some scanners are very noisy indeed. While this might not effect the final results it does reflect a poor level of engineering. If going for the top end of the market you should always expect the model to be "low noise."

Another thing to look for is whether the scanner needs one or two "passes" to create its image. While one pass models are often quicker, some two pass models claim that this helps create a better final image - so "one pass" is not always the headline advantage it is presented as in advertising.

While talking about time, the quality of central processor in your computer will play a role in how quickly the final image is presented. Equally the amount of memory (above the minimum required) can play a role in how fast the final image takes to be presented/manipulated on screen.

Scanners can be connected to your computer in several ways. The simplest is via the parallel port. Naturally this is usually the resting place for your printer lead so you will have to swap these over or go for a model that has a "pass through" option.

Modern computers sometimes have what is called Enhanced Parallel Ports (EPP) which are designed to speed up the flow of information to and from third party peripherals. While these might not add to speed in every case they are always backwards-compatible with normal parallel ports.

The second system is via the Universal Serial Bus (USB) slot that many more modern computers now have. Like EPP, USB was designed to increase the flow of data between the main computer and peripherals; and have the advantage of allowing devices to be changed with the computer still operating - the so-called "hot exchange" option.

The other method is via the Small Computer System's Interface (SCSI) that requires a special card and software driver. In most cases this will be provided with the scanner. Like the above system the advantages of this system nearly all revolve around operating speed. Due to its smaller market and manufacturing costs SCSI-based scanners are often markedly more expensive than same-spec parallel/USB models.

Image quality is always a controversial subject. While it is easy to look for Dots Per Inch markers (see out box) and "reading head" scan widths (commonly between 30 bit or 36 bit) a lot depends on the use you have for your scans.

For personal websites and small illustration nearly all the popular scanners on the market would probably suffice, but if you need scans for professional purposes far more care must be taken.

While journalists can describe image quality all day long it is never a substitute for seeing them yourself or judging them on your own working set-up. If everybody did this I'm sure half the digital imaging problems in the world would disappear!

Another important consideration is what you want to do with the final image. A high quality image from a high cost scanner will rarely shine when printed out on a low quality/cost printer. Once again a buro might help create that all important high quality final print - if you have no means of creating one yourself.

Support Glossary:

Copy Option: The ability to be combined with a printer to give a scanner an added photocopying option.
DPI: Stands for Dots Per Inch. Obviously the higher the number the greater the quality of the image will be. However, as image quality increases so does the memory take-up of the final "image file."
FAX Option: The ability to be combined with a modem and used as an out-going fax machine.
Greyscale: The number of shades of grey that are recorded when digitizing in black and white. In general terms the more the better.
Interpolation: A system that shares part of the pixel data between one pixel and its neighbours. In practice, allowing a wider range of colours without increasing the size of the "image file."
JPEG: Stands for the Joint Picture Expert Group. A (compressed) picture standard popular with images that need to be sent by Internet. Many scanner packages include software that allows picture formats to be swapped.
OCR: Stands for Optical Character Recognition. A method by which printed text can be transferred directly into a word processor compatible file.
Plug and Play: A widely used advertising phrase meaning the device is "easy to set up and use."
Software Driver: In general computing a piece of software that allows an optional piece of hardware to work. In this instance used to indicate the software that will regulate the flow of data to and from the scanner. Always make sure that your computer can accommodate this software - which will also require free harddisk space.
Transparency Option: A piece of optional hardware that allows images to be scanned from a negative on a flatbed scanner. Allows images to be taken without a final print or from slides.