A scanner provides a computer with its eyes, just as RAM serves as a computer's memory and the microprocessor behaves as its brain. The scanner's eyes allow the computer to communicate ideas visually. Through paintings on cave walls, picture-symbols on highway signs, and word-pictures such as black holes that stimulate images in the mind, humans instinctively rely on images to communicate. Although the personal computer excels at manipulating numbers and formatting text, a desktop system that lacks a scanner's eyes ignores the most powerful and efficient way to convey ideas. If you don't believe a picture is worth a thousand words, try to describe a scanned image using an 8-character DOS-style filename. Given the power and ease of incorporating images in your work and personal projects with a scanner, you won't have difficulty finding cool applications for an image capture device.

So What Can a Scanner Do?

Just look at what a scanner can do! Any reader of this book should find a half-dozen applications from the following list.

• Snag images for presentations. Whether you're working on a computerized slide show of your family vacation or a presentation for work, a scanner is the perfect tool for turning still photos into digital images that can be merged with text or recorded narrations (using sound capabilities from your PC or Mac) in professional-looking presentations.

• Convert images for Web pages. A personal Web page can include images of your family. A page put together for work can incorporate product photos or other images. A few tasteful images can turn any boring text-only Web page from a distraction into an attraction. In addition, you can distribute your images widely. A scanner lets you combine the quality, flexibility, and low cost of traditional cameras and photofinishing with Internet distribution. Figure 1-1 shows a typical Web page with scanned art.

Figure 1-1: A Web page can be spiced up with scanned art.

• Capture line art for publications. You have a piece of line art -- a one-color image such as a logo, decorative alphabet character, cartoon, or chart. You're on a short deadline and need to make some changes to the logo. Scanning and some touch-ups in an image editing program can provide you with the art you need in a few seconds.

• Capture photographs for placement in a publication. If the final destination for your images is a desktop publication (whether it's a company or personal newsletter, a self-published book of poems, or your holiday greetings), pictures captured by a scanner can spice up any document. If your publication will be printed on a conventional printing press, you can even handle adding the dot patterns called halftones to the images to aid in reproduction.

 

Tip: Even information sheets that will be photocopied look better with an image scanned and manipulated, rather than just subjected to straight photocopying.

• Capture low resolution images for screen display or positioning in publications. At times, super high quality isn't needed, because the image won't be used as is in the publication. Perhaps a high-quality scan using a professional device called a drum scanner is necessary. Even so, you can grab a version of the image using your scanner, for use as for position only (FPO) artwork. It's easier to visualize layout and finished appearance when you have a rough version of the actual image, instead of a gray or black box on the screen or in your proof printouts.

• Capture images for use as drawing templates. Sophisticated drawing programs such as CorelDraw and Adobe Illustrator are available for Macs and PCs today. A scanned image can be used as a template for tracing high-quality art. Some drawing programs even have an autotrace feature that takes care of this step for you. Adobe's Streamline program is a sophisticated stand-alone package that does nothing more than trace scanned images in a superior manner. When your scanned image has been traced, you can use it as is or refine the drawing with the various tools available in the drawing program.

• Create a computerized database. Perhaps you are developing a computerized multiple listing database for a real estate firm. While the finished listings and scans could be printed using desktop publishing techniques, it may make sense to keep the publication in electronic form. Potential homebuyers could look up information and view photographs of the house on the computer screen (or the firm's Web page). In such cases, superb images aren't essential, so quickie scans are just fine. In any case, the homebuyers will examine the properties in person. They will just view the scanned image for an idea of a given house's appearance. Other image-rich databases could include personal hobby collections or online family trees.

• Capture text in optical character recognition (OCR) applications. You'll often find that you have documents in hardcopy form that you'd like to edit using your word processor. These documents may include letters, brochures, newspaper articles, or other printed material. Once you're certain you have the legal right to use these documents, how can you translate it into editable form without retyping from scratch? Sophisticated OCR software can interpret just about any printed scanned image and translate into most common word processing formats.

• Grab images of three-dimensional objects. You have a product package or even a small product to include in a presentation, but no photograph. Some scanners, including most flatbeds, can capture images of any object placed on the scanning bed.

Make it simple to capture images of three-dimensional objects. Place the object on your scanner's bed, and scan to produce a view suitable for your application. Figure 1-2 shows a background created by scanning an array of pennies directly on the glass of a scanner.

Figure 1-2: Three-dimensional objects that are relatively flat can be scanned easily.

• Translate images into a format for facsimile transmission. Faxmodems for your computer receive or send faxes from your computer, but don't include a provision for capture. That's where your scanner comes in handy. At home, a faxmodem, scanner, and printer give you a complete two-way faxing system. At work, a scanner and a faxmodem enable you to bypass long lines at the departmental fax machine. Personal fax capability lets you keep confidential documents safe from unauthorized eyes.

• Add photos to your e-mail. Grabbing scanned images to incorporate in e-mail is fast and easy. What better way to get your message across electronically than with an eye-catching image?

• Create original art. Any scannable photograph or drawing can be further manipulated by the computer to produce a beautiful work of art. Figure 1-3 shows an image created by photographer/digital artist Peter J. Sucy. While the original photo is a powerful study in the strictures of inanimate bondage, a new layer of texture makes the image even more interesting after processing by the venerable Thunderscan scanner.

Figure 1-3: Digital art created with photography and a scanner (image courtesy of P. J. Sucy).

 

Tip: If you're interested in digital fine art, you can find more examples at Sucy's home page. (link no longer good)

Types of Scanners

We won't look at the mechanics of how scanners operate in this chapter. However, you should know that all scanners use a light source, some means of moving the sensor (or a mirror that reflects light to the sensor) over the surface of the artwork (or vice versa), and circuitry to convert the captured information to digital form. Different kinds of scanners usually arrange the components in various ways.

Drum scanners

The most expensive scanners are drum scanners, the high-price, higher-resolution color separation scanners typically found in the graphic arts industry. With drum scanners, the artwork is wrapped around a drum and rotated at high speeds. Laser light is usually used to illuminate tiny sections of the original. These scanners can provide highly-detailed image files that can be used for sophisticated layout and page composition, electronic retouching, and color separating. High-end scanners can also generate halftone dots electronically while exposing films used to make the printing plates.

Flatbed scanners

For good reason, the most popular style of scanner today is the flatbed type. This configuration provides the best and most flexible combination of features for most users. A flatbed can scan a variety of different originals, including thick originals such as books. If your artwork is too large to fit on a flatbed, you can scan it in pieces. With a special attachment, flatbed scanners can grab images of transparencies or color slides, and an automatic document feeder makes it possible to scan whole stacks of originals unattended. This versatility is hard to match.

Flatbed scanners look and work something like a photocopier: you lift the cover, place the original to be scanned face-down on the glass, and press a physical button on the scanner or click a button in your software. The key advantages of flatbed scanners are as follows:

• They can be used with a wide range of non-transparent artwork. Anything that is flat and can fit on the glass platen can be scanned. As with photocopiers that have hinged lids, you can place books, large originals, and thick copy face-down. Images up to 8 1/2 by 14 inches can be accommodated by the typical flatbed scanner, although some compact models limit you to 11-inch-long documents. As previously mentioned, very large originals can be scanned in pieces, and then "stitched" together within your image editing software.

• You can scan some three-dimensional objects. Keys, watches, human hands, and similar subjects can be captured with a flatbed scanner more easily than with sheetfed models, unless you have a very thin, flexible object. Don't count too much on this capability, however. Results will vary widely, depending on the scanner and the object being scanned, because the depth of focus (amount of the image above the surface of the glass that is sharp) is limited.

• A flatbed's artwork is fairly easy to align. Originals can be placed precisely on the flatbed scanner's scanning bed, using the built-in rulers and alignment guides. Sheetfed models can "drag" the original through slightly skewed, giving you a slightly warped image.

• Flatbed scanners can have the automation advantages of sheetfed scanners, when equipped with a mechanical multiple sheet feeders. Hewlett-Packard makes an especially nice model that comes furnished with both a 35mm slide adapter and a 25-page automatic document feeder. It's available with both USB and SCSI interfaces.

 

Tip: There is one key disadvantage of flatbed scanners: they have large footprints. These scanners take up a large amount of real estate on your desk, at least as much as your monitor or keyboard. For ease of use, you'll want to keep the scanner as close to your computer and keyboard as possible. That way, you can reposition a piece of art or replace an original with a new document without moving from your seat. However, this desk space is likely to be scarce and precious. Because the lid must be free to open, you can't put anything on top of a flatbed scanner, either. You may be able to place the scanner on a shelf next to your desk as long as there is plenty of open space above it..

Sheetfed scanners

Sheetfed scanners are firmly entrenched in their own niche. Originally popular because of their lower cost, they've recently enjoyed a resurgence because they are especially useful for those who need a scanner mainly for OCR or faxing. Sheetfed scanners have the built-in capacity to deliver ten or more sheets of paper to the scanner without user intervention. This capability makes sheetfed scanners a great option for processing documents or sending faxes. There are also portable sheetfed scanners with which you can take and scan anywhere. The latest models of this type use the USB port and draw their power from the computer directly, requiring no other external source. As you may guess, the key advantages of these units are as follows:

• Compact size. Documents that are longer than the scanner itself can be fed through, so sheetfed scanners can be built smaller than flatbed models. Sheetfed scanners that fit between the monitor and keyboard (and thus take up virtually no additional desk space) have been very popular.

• Automated operation. Because the paper is already being moved through the scanner, it's relatively simple to build a feeding mechanism to supply one sheet after another. This is particularly useful for OCR applications, in which you may be scanning multiple sheets from a single document.

• Low cost. Sheetfed scanners have traditionally been less expensive than the flatbed types because they are simpler to build. Instead of the complex moving light source or light source/mirror combination found in flatbed scanners, sheetfed models just have rollers to move the paper. However, this difference is vanishing as flatbed models reach lower price points. You can easily pay more for a higher quality sheetfed scanner than a bargain-basement flatbed.

Sheetfed scanners have many more disadvantages in comparison with flatbed models:

• Difficulty in aligning originals. You must be careful to feed originals into the scanner correctly. If one roller grabs the paper before the other, the page may feed at an angle. All this assumes that your original is placed at right angles to the edges of the paper. If the original is a photocopy that is skewed slightly, or if it was intentionally placed at an angle, you may be unable to correct this defect in the scanner at all. (It's easy to realign a crooked original on a flatbed's glass.)

 

Warning: Expect to have particular problems scanning very thin or slippery originals, which may not feed through a sheetfed scanner consistently. One workaround is to place the pesky original inside a clear plastic folder or sheet protector. This technique also works for very small originals. Some sheetfed scanners have a removable scanning head, so you can scan books or thin and small originals more easily..

• Limitations on originals scanned. To state the obvious, sheetfed scanners can work only with thin sheets of paper or similar materials. While you have fewer restrictions on the length of the original, there are strict constraints on the width and thickness. So, you may not be able to scan images from books or from wide sheets unless you photocopy them first. Pasteups and art on boards can also be difficult or impossible to scan with these models.

• Inconvenience with irregularly shaped and sized originals. For best scanning, the sheets you feed with these scanners must be relatively thin, rectangular, and sized about 8 1/2 by 11 inches. Very small originals, such as postcards, won't feed with some sheetfed scanners unless you tape them to a larger sheet or enclose them in acetate. Odd shapes, particularly items with curved edges, can also cause alignment problems.

• Possible damage to originals. In rare cases, it may be possible to damage your original accidentally as it is fed through a scanner of this type - a problem that almost never occurs with flatbed scanners. The rollers may put marks on the document or fold over one or more edges, especially when the original is old, fragile, or dog-eared. Pasteups must be put between sheets of acetate to keep the edges from catching. As with oversize originals, you can work around these problems by making a photocopy of the original.

In practice, jams may be few and far between. You may be more familiar with the operation of fax machines than sheetfed scanners. If you can't recall the last time you had an original jam in your fax machine, you're probably on the right track in estimating the reliability of sheetfed scanners.

Multifunction devices

Scanners aren't just for scanning anymore! Multifunction devices, which often combine scanning, printing, copying, and faxing capabilities, were developed to meet the needs of office workers, students, and home users with tight budget and space constraints. A multifunction device (MFD) for $500 or less may be your best bet for a scanner if versatility is at the top of your wish list.

MFD in the low price range are built around a color inkjet printer, which can be attached to your computer and used like any other printer. Some more expensive models, intended for the business market, use a laser printer for output. The vendor adds to the printer a sheet-fed scanner, which can capture an image of any photograph or document fed through the device. This simple add-on opens the door to several useful functions.

For example, a multifunction device can serve as a convenient photocopier. If you need a few copies, just enter the number of copies desired into a keypad on the front of the unit, and feed the sheets through. Many models can enlarge (blow up a three-by-five-inch notecard to full-page size) or reduce (squeeze a legal sheet onto an 8 1/2-by-11-inch copy you can punch and put in a notebook). The only drawback to using a MFD as a copier is the same as with any sheetfed model -- thick originals, such as books, can't be copied.

The scanner also allows you to capture graphics for your image editing or desktop publishing program, although low-cost devices generally have only a grayscale (not color) scanner. However, grayscale is entirely satisfactory for using a MFD as a fax machine using either the faxmodem built into the device or your computer's own faxmodem. Most also are furnished with OCR software; as a result, text documents you receive via fax or fed in using scanner mode are translated directly into editable text in your favorite word processing format.

 

Tip: Multifunction devices often contain their own memory, so you can use them as a copier or fax machine even when the computer is turned off. You can also receive faxes while printing or copying is underway - each job will take its turn..

Other scanners

There are a few more types of specialized scanners that we'll mention only in passing. The most useful is the photo scanner, which is aimed at consumers. These scanners accept snapshot-sized photos, and convert them into scanned images you can manipulate or immediately print out with a photo-quality inkjet printer.

Slide scanners are scanners designed specifically to scan 35mm slides, usually for professional applications. You'll also encounter transparency scanners for grabbing images from 6 cm by 6 cm and larger negatives or transparencies. Unless you're a photo buff with a large collection of slides, you probably won't need this capability. If so, there are attachments for many flatbed scanners that allow capturing images from transparency originals.

If you look hard enough, you may also find handheld scanners, video scanners, and overhead scanners that look like a photographic enlarger.