CompTIA A_ Certification All-In-One Exam Guide, Seventh Edition - Michael Meyers [311]
Modern scanners come in 24-bit, 36-bit, and 48-bit variations. These days, 48-bit scanners are common enough that you shouldn’t have to settle for less, even on a budget. Figures 18-32, 18-33, and 18-34 show pretty clearly the difference resolution makes when scanning.
Figure 18-32 Earring scanned at 72 dpi and 24-bit color
Figure 18-33 Same earring, scanned at 300 dpi and 24-bit color
Figure 18-34 Same earring, scanned at 1200 dpi and 24-bit color
Scanners differ a lot in grayscale depth, a number that defines how many shades of gray the scanner can save per dot. This matters if you work with black-and-white images in any significant way, because grayscale depth is usually a much lower number than color depth. Current consumer-level scanners come in 8-bit, 12-bit, and 16-bit grayscale varieties. I recommend 16-bit or better.
Connection Almost all modern scanners plug into the USB port on your PC, although some high-end models offer FireWire as well. Older scanners come in SCSI and parallel varieties.
Scanning Speed Scanners have a maximum scanning speed defined by the manufacturer. The time required to complete a scan is also affected by the parameters you set; the time increases as you increase the amount of detail captured. A typical low-end scanner, for example, takes upwards of 30 seconds to scan a 4 × 6 photo at 300 dpi. A faster scanner, in contrast, can crank out the same scan in 10 seconds.
Raise the resolution of the scan to 600 dpi at 48-bit resolution, and that faster scanner can take a full minute to complete the scan. Adjust your scanning settings to optimize for your project. Don’t always go for the highest possible scan if you don’t need the resolution.
Connections matter as well. A good Hi-Speed USB scanner can scan an 8 × 10 image in about 12 seconds at 300 dpi. I made the mistake of taking the scanner to a friend’s house to scan some of her jewelry, but she had only a Full-Speed USB port. I plugged the scanner into her PC and it took about 45 seconds to scan each 8 × 10 image. We were up all night finishing the project!
Installation and Scanning Tips
Most USB and FireWire devices require you to install the software drivers before you plug in the device for the first time. I have run into exceptions, though, so I strongly suggest you read the scanner’s documentation before you install.
As a general rule, you should obtain the highest quality scan you can manage, and then play with the size and image quality when it’s time to include it in a Web site or an e-mail. The amount of RAM in your system—and to a lesser extent, the processor speed—dictates how big a file you can handle.
For example, don’t do 8 × 10 scans at 600 dpi if you have only 128 MB of RAM, because the image file alone weighs in at over 93 MB. Because your operating system, scanner software, image-editing program, and a lot of other things are taking up plenty of that RAM already, your system will likely crash.
If you travel a lot, you’ll want to make sure to use the locking mechanism for the scanner light assembly. Just be sure to unlock before you try to use it or you’ll get a light that’s stuck in one position. That won’t make for very good scans!
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EXAM TIP The CompTIA A+ certification Practical Application exam tests you more thoroughly on troubleshooting scanner problems and preventive maintenance issues than does the Essentials exam. Look for questions on using the locking mechanism, keeping the scanner surface clean, and avoiding scanning sharp objects that could damage the scanner.
Digital Cameras
Another option available for those not-yet-taken pictures is to put away your point-and-shoot film camera and use a digital camera. Digital cameras electronically simulate older film technology and provide a wonderful tool for capturing a moment