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Point, click and scan!
A FEW years back when scanners first hit the computer scene, they belonged to the realm of imaging studios, graphic artists and publishing professionals. Times have radically changed since then. These days, after colour printers, scanners have singly become the most sought-after PC peripheral for home users.
Whether this will be your first scanner purchase or an upgrade to a better-quality one, this guide will provide you the essential information you need to make the right decision.
In simple terms, a scanner captures and converts images to a computer format. Essentially, it transforms analogue data to digital information. To accomplish this, scanners have small electronic “eyes” made of photosensitive cells that detect the intensity of light reflected off the item being scanned. A converter then digitizes this information and puts it in a form understood by the computer.
Types of scanners
Several types of scanners are available in the market in distinct price ranges. Most commonly available are flatbed scanners, so named because the scanning surface is flat. In addition, other types of scanners include sheet-fed scanners, slide (or photo) scanners, handheld scanners and multifunction peripherals with each one having a certain typical feature.
Sheet-fed scanners have decreased in popularity owing to the fact that some of the models available scan a single sheet of paper at a time and require that the documents be fed manually through a feeder. Consequently, they are best for individual pages.
Slide scanners, specially dedicated ones that only handle 35mm slides, are very expensive. Still, they may be the right choice for those looking for high-quality scans of more than a few film negatives and slides.
Multifunction devices that incorporate a printer, scanner, and copier into one device are relatively new innovation that aren’t very common as yet.
Picture perfect?
Choosing a scanner isn’t easy. Individual models differ from each other in several ways. But fortunately for us, today’s moderately priced scanners boast a wealth of advanced features, such as a very high 1200 or 2400-dpi resolution, transparency adapters, a large scanning area and USB 2.0 connections.
Before you go shopping, there are a few technical aspects you need to understand. These key points are outlined below:
Resolution: This is a measurement of how many pixels a scanner can sample in a given image. It is usually measured in dots per inch (dpi) and is quoted both horizontally and vertically. Generally, the higher the resolution, the costlier the scanner but the better the result.
Resolution is of two types: Optical and Interpolated. The former determines how many pixels a scanner can actually “see” and is more important as it is a very reliable indicator of image quality. Don’t be fooled into mistaking the latter for optical resolution. As a rule of thumb, always ignore interpolated resolution. In addition, remember the smaller of the two values when quoting the optical resolution.
Normally, a 300-dpi scanner is best suited for displaying images on a screen. For general printing purposes, 600-dpi is ideal. But for printing large, detailed photos or enlarging small images, opt for one with 1200-dpi or 2400-dpi optical resolution.
Bit-depth: This is the information recorded by a scanner after converting something into digital form. The higher the bit-depth, the better the scanner is at distinguishing between close shades of the same colour. This results in higher image quality. Most colour scanners today are at least 24-bit (“true-colour”) although 36-bit and 48-bit scanners too are getting popular. But for almost all types of general-purpose use, 24-bit colour depth will suffice.
Optical density: OD or dynamic range is a measure of how wide a range of tones a scanner can record (from bright highlights all the way to dark shadows). It is measured on a logarithmic scale from 0.0 (pure white) to 4.0 (pure black). For a particular scanner, this value gives an indication of how much of the range it can distinguish.
If you have to deal mostly with photos, you need an OD of around 3.0. For slides and transparencies, you need a higher OD, preferably 3.2 to 3.4. But don’t be surprised if you can’t see this value in the specs of some models.
Interface: You can connect your scanner to your PC in a number of ways. Parallel ports tend to be the slowest. Faster replacements include USB 1.1, USB 2.0, SCSI and FireWire connections. Some scanners offer dual interfaces, like USB and parallel, for compatibility with older PCs. Those with FireWire connections typically cost more and are designed for professional users.
Speed: This factor depends on the resolution. The higher the scanner’s resolution, the longer you’ll have to wait. Checking units for speed is difficult as there’s no fixed standard set by manufacturers. Generally, those scanning a few times a day won’t be bothered by this factor as compared to those who’ll be constantly scanning images.
Sensor technology: Flatbed scanners have one of two types of sensor technology: a charge-coupled device (CCD) or a contact image sensor (CIS). CCD-based scanners, the older technology, use a system of mirrors, a lens and a light source over a document to focus the image on the chip.
On the other hand, CIS-based scanners replace this entire set up with a single row of sensors placed extremely close to the document. Although they produce scanned images that aren’t as good in resolution and quality as those on their counterparts, CIS scanners tend to be much thinner, cheaper and less power hungry than CCD scanners. On the down side, CIS scanners can’t use transparencies or automatic document feeders.
Scanning area: It refers to the maximum image size a particular unit can scan. While majority of the users have little need for this feature, those who work frequently with large documents will appreciate the flexibility. A larger scan area is good for scanning large books, maps, drawings, paintings and newspapers.
Most sheet-fed scanners can easily scan 8.5”x14” documents. Among flatbed scanners, there are units that can scan only an A4-sized (8.5”x11”) page and those that can handle a full legal-size (8.5”x14”) scan.
Software: The bundle software included is common to every model these days usually contains Windows XP-certified drivers, colour calibration and image-editing software as well as optical recognition software (OCR).
Colour calibration software, as the name implies, is used to maintain the original colours of the image throughout processing. This means that what you see on the monitor and what you print out should be reasonably close to the original, in terms of colours.
Basic image-editing software (included with most units) can be used for touching up colour imperfections and optimizing files for emailing or printing purposes.
OCR software allows you to scan a printed document and convert it to editable text on your PC. Special OCR-based programs examine the scanned image and convert it into a format that can be read by a word processor, spreadsheet or database.
The final consideration is the accessories or attachments you can fit in your scanner. These usually include a Transparency Adapter (TA) and an Automatic Document Feeder (ADF).
TA is required for scanning slides or 35mm film. Some models have it integrated on their covers, making the lids rather bulky, while others have separate plug-in modules that reside on the glass. ADFs, on the other hand, are either built into or replace the scanner’s lid. They are essential for high-volume scanning and also for pages longer than a flatbed’s surface.
Top of the line
The best flatbed scanners that combine convenience, quality, speed and economy are listed below. Prices given are approximate and in ascending order.
Epson Perfection 636U: Priced at Rs3200, this unit is simple-to-use for new users with features: 600 x 2400 dpi, 11.3” x 16.8” scan area, USB interface
Canon CanoScan LiDE 30: Affordable and compact, this high-resolution scanner is available for Rs4500, with additional features such as: 1200 x 2400 dpi (48-bit depth), 8.5x11.7 inch scan area, USB 2.0 interface.
Canon CanoScan 5000F: Exceptional image quality; built-in film adapter for 35mm film; one-touch operation with 2400x4800 dpi (48-bit depth) and 8.5”x11.7” scan area are some of its salient features which is ideal for enthusiasts and costs Rs7800.
Epson Perfection 1660 Photo: With a value of Rs8500, it has 1600 x 3200 dpi (48-bit depth), 8.5”x11.7” scan area and USB 2.0 interface. Its other features include good speed and one-touch operation. It is a great choice for photo enthusiasts.
Epson Perfection 3200 Photo: Priced at Rs25000 this fast processing scanner is for professional use. With 3200x6400 dpi (48-bit depth), it has a scan area of 8.5”x11.7” with USB 2.0 interface and FireWire port. It provides very high resolution and is great for high-speed film scans.
Can I have it too?
Scanners are an excellent addition to any computer system. Today cost and technology trends have continued to work in consumers’ favour. As prices continue to plummet, now may be a good time to reach out and grab one of these invaluable asset to any PC user.
The writer
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