These are really useful peripherals that allow you to digitise documents for storage and editing purposes on your computer; everything from text to photos and magazines. They were, until quite recently, relatively expensive. Now, with improvements in their design, their popularity has soared as prices have fallen, making them easily available for home and home/office. Before you buy, think about the type and size of the originals you’ll be scanning; this will help determine the model that you should choose. They come in four basic types:
Flatbed Scanners (also called Desktop)
These are the most readily available and can scan flat documents as well as small 3 dimensional objects (such as books). They look like a photocopier. Most will scan A4 size but there are some designed to scan up to A3 size originals. The scanning “beam” moves over the paper to capture the image. Most will have to be “fed” pages singly unless there is an automatic document feed attached (this sometimes has to be purchased separately) allowing you to scan much faster. Some Flatbed Scanners are available with a TRANSPARENCY ADAPTER that have a separate light source, allowing you to scan slides and transparencies as well as regular documents. This may be a good choice for you if you’ll only be scanning slides or transparencies occasionally.
Sheet Fed Scanners
Are perfect for digitising and storing pages of text. They are usually cheaper than flatbed models as there use is a somewhat limited. With the aid of OCR (Optical Character Recognition) software built-in you can scan a page and have the image of it on your screen in seconds. The image may not always be 100% accurate although these types have improved in recent years. As with flatbed scanners, automatic document feeders are sometimes available allowing you to load several pages ready for scanning, making the job less of a chore. This type works by the paper moving across a fixed scanning “beam” to capture the image, unlike Flatbed types where the beam moves. Therefore, the length of the original can be longer than A4 but the width that can be scanned may only be up to A4 size. They are also available in a portable and hand-held versions which although are cheap to buy, tend to be quite slow and are only really useful for very limited situations.
Slide/Film Scanners
As their names suggests are specifically designed to scan 35mm slides and negatives only. These need special handling due to their transparency and size. Some multi-function scanners do have the capability of scanning slides and negatives, but if you’re going to be doing hundreds then you may be wise to opt for this specialised solution. These types of scanners are more expensive but are really worth considering if you’re thinking about creating a permanent archive.
Drum (or Rotary) Scanners
These can be found at the top of the range and are designed for professional, high-volume use. The image is passed across the Photomultiplier tubes (PMTs) several times on a rotating drum at high speed to achieve accurate imaging. Flatbed and Sheetfed Scanners use charged coupled devices (CCDs) and contact image sensors (CIS) which are less sophisticated and costly, which is why Drum Scanners are only usually be found in service bureaus and at graphics professionals.
Apart from the above choices, there are a number of other factors that may affect your choice of model. The scanners’ overall performance is determined by its Colour Sampling Depth, Optical Resolution and Software – so read on and find out what this all means...
Colour Sampling Depth
This is measured in bits and refers to the number of colour variations that the scanner can recognise, and therefore digitise, of the scanned image. The higher the number is, the more colour variations there will be so the scanned image will be truer to the original. Most scanners are now at least 24 bits which means it can distinguish over 16 million different colour variations!
Optical Resolution
Means the number of separate dots or points that the scanner can sense, and therefore digitise, on a page. It is measured in “dpi” (dots per inch) or “ppi” (points per inch) and is measured horizontally and vertically. Again, the higher the numbers, the better the resolution should be, giving a more accurate result. Most modern scanners will have a resolution of at least 600x600ppi.
Software
All scanners come with some degree of image editing and OCR (Optical Character Recognition) software allowing you to perform at least basic functions once the image is on your computer. When deciding which one to choose, look carefully at the software that’s offered to make sure it enables you to do everything that you would like with your scanned documents. If you will need specialist editing software (such as cropping etc. for photos) then make sure it’s included in the package, or can be added to it, if necessary.
Connections
All Scanners will connect to your computer by one of the following methods so you need to make sure you have compatible connections:
- Parallel Port – This has, until recently, been the most common interface between computers and scanners and is now be superseded by -
- USB (Universal Systems Bus) which gives a better performance and is fast and easy to use
- SCSI (Small Computer System Interface) connections are only usually seen on scanners at the top of the range
- FireWire gives fast connections as is becoming more widely used
General
If you choose carefully, scanners can be an invaluable aid to storing and editing documents of all types for archive or creative purposes. They are now more affordable than ever before and even a modest outlay will get you professional looking results. Make sure that you buy the right size for the type of documents that you’ll be scanning and that the overall software allows you all the post-scanning functions that you will need.
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