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Digital photography All-in-one desk reference 3rd edition - Busch D.

Busch D. Digital photography All-in-one desk reference 3rd edition - Wiley publishing, 2006. - 755 p.
ISBN: 0-470-03743-1
Download (direct link): digitalphotographyallinone2006.pdf
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Book I
Chapter 3
Acquiring Your Digital Pictures
Grabbing Digital Images of Prints and Slides
Today, unlike times past, you donít have to agonize over what category of scanner to buy. That should be obvious from the kind of scanning you want
to do:
? Flatbed scanners are used for scanning reflective copy, such as documents, photographs, articles torn from magazines, and other similar material. You simply place the original face-down on the scannerís glass platen, and a moving bar with a light source and a sensor (or a mirror that reflects the light to a sensor located elsewhere in the scanner) captures the image a line at a time when you close the lid and activate the scanning software.
Some flatbed scanners have a light source built into the lid (or another component), as shown in Figure 3-3. This light source can transilluminate a negative, slide, or transparency so that you can use the flatbed to grab images from transparent originals. These scanners can do a good job in non-critical applications.
? Slide scanners are specialized scanners designed to scan slides and transparencies. They often have the higher resolution needed for scanning the 24mm x 36mm area of 35mm slides and often cost quite a bit more than flatbed scanners. There are also dedicated transparency scanners for larger size film, too, such as 120/220 roll film and sheet film, including 4-x-5-inch, 5-x-7-inch, and larger sizes. Theyíre largely used by professional graphics workers.
? Photo scanners are simplified scanners that convert snapshots to digital format. Deposit your standard-sized photo in the scanner, and it grabs an image for you to edit. Photo scanners are sometimes mated with color printers so that you can make copies of prints as quickly as you can feed them into the scanner. Although popular at one time, this type of scanner is no longer widely available.
Figure 3-3: A light source built into the lid allows a flatbed scanner to capture slides.
What to look for in a scanner
When shopping for a scanner, youíll want to look for a few important things. Hereís a quick summary (see Book II, Chapter 4 for more details):
Grabbing Digital Images of Prints and Slides
? Resolution: Scanners generally have a lot more resolution than you need, measured in samples per inch (spi). Youíll also see the terms dots per inch and pixels per inch applied to scanners, even though scanners donít have dots (printers do) or pixels (monitors do). Scanner resolution varies from 600 x 600 spi to 2400 x 2400 spi or higher. Unless youíre scanning tiny, very high-resolution originals (such as postage stamps), anything more than 300 or 600 spi is overkill. I explain why in Book II, Chapter 4. The difference between 300 spi and 2400 spi resolution is shown in Figure 3-4.
Figure 3-4: A 300 spi scan of a small, detailed object (left) isnít sharp enough. The 2400 spi scan (right) looks much better.
? Color depth: This is the number of colors a scanner can capture. The color depth is measured using something called bit depth. For example, a 24-bit scanner can capture 16.8 million different colors; a 30-bit scanner can grab a billion colors; and a 36-bit or 48-bit scanner can differentiate between . . . zillions of colors. Youíll never have an original with that many different hues, however. In practice, the extra colors simply provide the scanner with an extended range (called dynamic range) so that the scanner can capture detail in very dark areas of the image as well as in very light areas.
Book I
? Speed: Some scanners are faster than others. If youíre scanning a lot of photos, youíll want one that works quickly.
Chapter 3
Acquiring Your Digital Pictures
Letting a Professional Do It
? Convenience: So-called ďone-touchĒ scanners have buttons mounted on the front panel so that you can trigger the scanner to make a copy (thatís sent to your printer), scan to a file, route a scan to e-mail, capture text with optical character recognition (OCR), or perform other functions.
? Bundled software: The best scanners are furnished with an easy standalone software interface plus a more professional scanning program that gives you total control over every scanning function. You also get drivers that let you access these interfaces from within programs, such as Photoshop. You may even get Photoshop Elements bundled with the scanner, plus software to create panoramas, build Web pages, manage documents, and do other fun stuff.
? Accessories: Some scanners include sheet feeders (for scanning a stack of documents) or can be fitted with them as an option. Others have slide-scanning attachments or built-in slide-scanning tools. Depending on the kind of work you do, these accessories can be a perk or a necessity.
Letting a Professional Do It
Sometimes you donít need to convert an image to digital format yourself. Professional services can do that for you. These range from stand-alone kiosks at your local department store (with a built-in scanner and printer) to services that your local photofinisher offers. When you take in your film for processing, your local lab can give you the same set of prints or slides that you have always received or return your images already scanned onto a Kodak Photo CD or Picture CD. Some mail-order firms offer the same service.
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