A scanner is a peripheral device which enables to digitalise documents. It is the perfect instrument to transform your souvenirs and written papers into digital documents that time won't wait for. Some scanners are capable of digitalizing any type of document; others are destined for specific formats, from the most common to the most particular (such as business card scanners). There exist a scanner for every use, but there will be necessarily one which will be the connection between yourself and your computer.
Look before Buying Scanner
Different Type of scanner
What differentiates all these scanners, before any technical considerations, is the type of documents they are capable to digitalise.
* Sheetfed scanner
The sheetfed scanner is uniquely capable to digitalise sheet per sheet. It is enough to put your sheet into a feeder or directly into an opening for it to appear just a few seconds later unto your screen. This type of scanner is very compact but very limited in its usage. In fact, it has a tendency to disappear.
* Flat scanner
The flat scanner is the most common type of scanner. It can digitalise all types of documents, of different sizes (more often A4, but there also exists A3 scanners). To digitalise your document, you just need to place it against the device's screen. Today many flat scanners propose in option a back for your transparencies. This option allows you to digitalise all types of transparent documents, including documents on film transparencies and negatives (24x36 films...). You got it; this is currently the type of scanner the most polyvalent available.
* Film scanner
First and foremost destined for professionals, the film scanner is specialised in the digitalisation of 24x36 negatives or APS. It can achieve very high resolutions and its quality is excellent, but its use domain is very restricted.
Other types of scanners exist, even more specific, such as business card scanners (useful when you have a large batch of contacts to manage), barcode scanners or pen scanners allowing you to digitalise a single line of text at a time.
A scanner of:
10 bits can distinguish 1,024 colours.
24 bits can distinguish 16.7 million colours.
42 bits can distinguish 440 billion colours.
Today a scanner must at least be capable to sample 24 bits.
Optical resolution: in "dot per inch" (dpi) or "point per inch" (ppi)
It is the number of points that the scanner sensor is capable to distinguish on a surface per square inch. Today it is crucial to choose a scanner digitalising at a resolution of at least 600x600 ppi.
Colour sampling depth
Measured in bits, it is the number of colour gradation that the scanner is capable of dissociating. The higher their number, the better the colour gradation will be restored and the more your document will be faithfully restituted.
Interfaces
Nowadays, scanners propose different types of interfaces, sometimes even simultaneously. You must, of course, have the appropriate port in question on your computer.
* Parallel Port
The parallel port is the most widely used interface on scanners and printers for several years. It is today phasing out, taken over by USB (Universal Serial Bus) which offers superior performances and a reduced processor's resources usage.
* USB (Universal Serial Bus)
As with most actual peripherals, scanners can connect to your computer via a USB port. Very fast and practical to use, this interface is also compatible to both PC and Mac, and certain scanners can be even fed (electricity wise) directly from the USB port.
* SCSI (Small Computer System Device)
Destined above all for professional and work stations, the SCSI interface has the lowest processor resources consumption. These types of scanners are becoming rarer and are often top of the range models.
The software
The programs delivered with the scanner are classified primarily into two large categories:
* Image editing
The provided versions are usually lighter versions of the commercial software which cost several hundreds of pounds. They are good enough for small works but can appear more limited for an advanced editing.
* Character recognition
Also named OCR, it is a major advantage of scanners. Thanks to this software, they can read a "text image" and transform it into a classical text document, while keeping page-setting, the images and illustrations of the original document. Today the rate of recognition nears 100% but some small manual improvements may be sometimes necessary.
Some scanners are pretty and slim, others austere and massif. Some are equipped with buttons in frontage which make it possible to automate certain tasks (such as for example the launching of a photocopy or a digitalization by the simple touch of a button), others can also function whilst maintained vertically. Depending on the main use of your scanner it may be appealing to look into these kinds of annexed functionalities.
Find more about Scanners at www.ShoppingSoLow.com.
About the Author
Vinay Choubey
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