A scanner is an essential device in most of the offices today. It is the basic peripheral for PC users especially for publishing and imaging professionals to e-mail photos to anyone. The key purpose of this device is that it converts a hardcopy document into digital form. To choose a scanner, one should know about the basic functionalities of the device including the quality, output, speed and software equipments. Most of the scanners available nowadays have the advanced features like 4800 dpi (dots per inch) resolution, transparency adapters and USB 2.0 connections.
Key Features:
Optical Resolution: While buying a scanner, one should know about the resolution offered by the device. Dots per inch, shortly known as dpi are used to measure the resolution. 300 dpi is the standard resolution for capturing texts using optical character recognition. You can also scan larger images with a size of 8 x 10 inches at a very high resolution. But a 4 x 6 photo, 2400 DPI can consume a very large amount of space in the hard disk taking excess of time.
Transparency Adapter: A transparency adapter is required for scanning slides or films. A light source that shines through the film is generally detained in place with a template. These transparency adapters are built into a scanner’s lid as detached sections that plug in and sit on the scanner’s glass. A separate TA (transparency adapter) allows keeping the lid thin or incorporates an automatic document feeder into the lid. Transparency templates are of different sizes, the smallest holding only one slide, many others sized for three slides or a 6 Inch long filmstrip.
Automatic Document Feeder: This is helpful to handle high volume optical character recognition or for scanning pages that is much longer than a flatbed scanning surface. Typically ADF is used to replace the scanner’s lid. Epson, Microtek and HP offer aftermarket ADF for some of their models.
Interface: Scanners come with a USB 2.0 interfaces, which is backward compatible with the USB 1.1 connections. Some scanners also offer a fire-wire connection.
Colour Depth: The amount of colour and grey scale data, a scanner can recognise and save is the colour depth that is measured in Bits per Pixel. A scanner can save more data than its driver can save, so a qualifier appended to the bit-depth spec such as 48- bit internal or hardware colour describes how much data the scanner drive can save. Generally the 24 Bit external colour depth is sufficient.
Sensor Technology: A Charge Coupled Device CCD or a Contact Image Sensor CIS are the two types of sensor technology the flatbed scanners have. The CIS is the latest scanning technology, but they produce a slightly lower quality scanned images. They are much smaller and use very little power when compared to the CCD based scanners. The CIS can be easily powered with a USB cable.
Scanner Types: The prominent ones in use today are the flatbed scanners, called so as the scanning surface is flat. Other than the flatbed scanners there are sheet-fed scanners, handheld scanners, film scanners and multi-function peripherals that incorporate a printer, scanner and FAX machine in one device. Sheet-fed scanners are no longer popular as they are less versatile and work best for individual text pages. As the document slides in through a feeder, as in the case of a Fax machine, photographs emerge bent and books cannot be crammed into it either.
Software: To resize or crop the image, adjust the brightness and contrast or reduce the red-eye effect of the photography. Most scanners are equipped with the simplified versions of image-editing software that can touch up the imperfections or optimise the files for e-mailing and printing. Higher end scanner model includes the Adobe Photoshop for an extensive image manipulation. Many scanners are also equipped with Optical Scanner Recognition allowing one to scan a printed document and convert it to text.
The specs explained: The more advanced the technology, the higher is the price and better the components. When checking the resolution figures, the lower of the two numbers indicate how many dots the scanner can capture in each linear inch of the scan head, called the Optical resolution. The larger number is the number of ‘lines’ the head captures as it scans each inch of the photo or document.
On high-end scanners, a specification for Dynamic Range or Dmax specifies the sensitivity of the device in rendering the lightest and darkest colours and shades of an image. Dmax is a logarithmic system, so a scanner with a reading of 3.6 or 4.2 rating has a better range than the 3.2 Dmax rated system, which is quite good.
Scanner Shopping tips:
• The common model that is easy to use is the Flatbed model.
• Handheld ones are ideal for students and lawyers, as they have to scan short-text messages frequently. They are a bit expensive, but it is cost effective as most of the libraries do not allow taking their books outside the premises when copying is required.
• Lookout for a minimum of 2400 DPI optical resolution.
• Check for the PC’s USB port. Scanners can be connected to the PC with a USB port. If the PC is more than a couple of years old, then it’s likely to have a USB 1.1 Port. The current scanner modes have a USB with 2.0 ports, the connectivity providing a speedier and faster transfer. To use the USB with 2.0 at its optimum, either purchase a new one with 2.0 ports or install a USB 2.0 port in the prevailing PC.
• For businessmen and others who do high-volume or specialty scanning, advanced options like automatic document feeders, transparency adapters and a scan bed, large enough for legal-size documents can make quite a difference. Legal-size scan beds are ideal for scanning large illustrations, diagrams, paintings and labels (like that on product boxes), as well as tabloid-size pages.
Whatever the reason is for buying a scanner, options at economic prices are varied. There are different kinds of scanners in the market offering range of features. So when you plan to purchase one, carefully have a look at all the features and get the best for you.
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