BOOT CAMP ARCHIVE 1998

  

 

BOOT CAMP 025

PCs & PICTURES PART 1, SCANNERS

Getting photographs into a PC used to be incredibly difficult. As recently as five years ago it was almost impossible, without access to eye-wateringly expensive peripherals. It's also worth remembering that the PCs of the early 1990s (mostly 386 and 486 machines with 8Mb of memory or less), were only barely capable of displaying and processing high quality colour pictures. That's all changed, today's Pentium PCs are cheaper, faster and vastly better equipped to handle photographic images. Competent colour scanners now sell for less than £100 and digital still cameras are not far behind -- we'll be looking at them in more detail in part 2. 

This week however, is devoted to colour scanners, and why your life is incomplete without one. A scanner is arguably the most versatile computer peripheral yet devised. It will enable you to load high quality photographs and images into your PC, for incorporation into documents, presentations, newsletters and Internet web pages. Most models also come with a suite of utility software that can turn your computer into a sophisticated photo studio, colour photocopier, fax machine and document reader.

First generation scanners were cumbersome to install and use but most recent ones, including many current budget models, can be up and running in a matter of minutes. There are basically two types of general-purpose scanner, utilising two sorts of PC connection. Most non-specialist models are either flatbed or sheet-feed; a few hand-held models are still available but they're virtually obsolete now.  A flatbed scanner looks like a small photocopier. The image or document is placed face down on a glass plate or 'platen' and scanned by a moving image sensor, on the other side of the glass. On a sheet feed scanner the image sensor is static, the document moves past it, drawn though a set of rollers, rather like a fax machine. Flatbeds can take up a lot of desk space but they are able to scan unwieldy objects like books or irregularly shaped items. Sheet feed scanners are usually a lot smaller or incorporated into multi-function devices like combined printers and fax machines, but they can only cope with a single sheet of paper.

Scanners either come with their own interface card or they connect to the PC's printer port. The former means you will have to open up your PC, and it must have a vacant card slot on the motherboard for the SCSI card (see jargon filter). They tend to be more expensive too but they're also slightly quicker, however, scan speed is largely irrelevant. Unless you're planning to regularly process large number of images saving a few seconds is hardly important. Parallel port scanners are suitable for 95% of home and office applications, the only minor limitation is that you cannot scan and print at the same time, though the printer remains connected to the PC, via a 'through port', on the back of the scanner.

Scanner resolution creates a lot of confusion. Resolution is a measure of how much fine detail the scanner can capture. The only figure that counts is optical resolution, which is typically quoted as a set of two numbers, i.e. 300 x 600 or 600 x 1200 dots per inch (dpi). The first figure indicates how many light sensitive elements or pixels there are on the scanner pickup head, that traverses the image or document. The second number shows how many vertical 'lines' can be scanned by the pickup head, as it steps along the picture or document.

The important point to bear in mind is that most applications -- where the scanned image will be shown on a PC monitor screen, or printed out by an inkjet printer -- calls for a resolution of between 100 and 200dpi. Good quality colour photographs may go up to 300dpi, but only a handful of professional applications need 600 dpi or above. A lot of budget scanners claim to be able to resolve 2400, 4800 dpi, or more, but that is an 'interpolated' figure, which basically means the software guesses at what's in between the actual scanned dots. A lot of the time it gets it wrong and interpolated scans can look soft or slightly blurry. Another point to bear in mind is that higher resolution scans take longer, use up more hard disc space and memory to store and manipulate the image. A 4 x 6-inch colour photograph scanned at 2400 dpi would swallow up several hundred megabytes of memory!

A scanner is heavily dependent on its operating software. All models require a driver program, the most common one is TWAIN (see jargon filter), it operates in the background, usually from within the scanner's user interface. This is normally features a preview window -- showing a small thumbnail version of the scanned image -- plus a set of control buttons. The driver automatically adjusts brightness, colour and contrast (manual controls are usually there if you need them), all you have to do is select the resolution and the task (i.e. picture acquisition, copier, fax, document reader etc.). Incidentally, Windows 95 comes with a simple scanning utility. It's called Imaging and can be found in the Accessories folder on the Programs menu.

Most scanner operating programs have the facility to make a fast preview scan, to check orientation and alignment etc., before the full scan. When it has finished the image is automatically routed to the appropriate application. For example, if it's a photograph the picture will appear in an open window on the desktop of the selected graphics program. If it's a fax, the scanned document opens your fax software and a document to be converted into text first passes through an optical character recognition (OCR) utility where it is converted into a text file, which can be read by your PC's word processor. Most scanners come bundled with graphics and OCR programs, though more often than not they're 'lite' versions with a limited range of features.

Before you rush out and buy a scanner there's a couple of points to bear in mind. Scanners work best with fast Pentium PCs and Windows 95 -- the faster the better! If you're using an old 486, forget it, no matter what it says on the scanner box. Scanners also need lots of memory and hard disc space, reckon on at least 32 megabytes of RAM, (64Mb is better still…) and several hundred spare megabytes on the hard drive.

Next week -- digital cameras in the frame

JARGON FILTER

OCR

Optical character recognition -- software that translates a scanned image of printed or typewritten text into a plain text file that can be read by a word processor

SCSI

Small systems computer interface or 'scuzzy', a high-speed data interface that uses a card, which plugs into an ISA (integrated system architecture) socket on the PC motherboard. SCSI cards that use PCI (peripheral component interconnect) slots are also available

TWAIN

Technology Without An Important Name, an industry-standard software utility that operates in the background, acquiring an image from a scanner or digital camera

TOP TIP

If you're spending several hours each day staring at your computer's monitor screen it's important to make sure it is properly set-up. Incorrect picture settings can result in fatigue, headaches and eyestrain. Adjusting brightness and contrast by eye can be quite difficult. Monitors also go out of alignment, but some picture faults-such as slowly deteriorating focus, geometry or colour registration is difficult to spot in their early stages. For that reason it's worth periodically checking your monitor with a program such as Ntest. It was created by Nokia's monitor division and features a dozen test patterns, to help you set up your monitor and give it a complete health check. What's more it's free! You can download NTest from the Nokia web site; it is a 1.2Mb zip file, so you will need a decompression utility like WinZip to open it up.

http://www.nokia.com/products/monitors/

monitor_test.html

http://www.winzip.com

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