The Essentials of Digital Imaging


Like the digital audio world and other specialized fields, digital imaging has its own jargon and technical concepts to understand. You can accomplish a lot in iPhoto without having to know these things, but a solid foundation in imaging essentials will help you get more out of iPhoto, your digital camera, and other imaging hardware.

There are two key points to take away from this little lesson. First, although iPhoto works beautifully with digital cameras, it can also accept images that you've scanned or received from a photofinisher.

Second, the concept of resolution will arise again and again in your digital imaging endeavors. You'll want big, high-resolution images for good-quality prints, and small, low-resolution images for convenient emailing to friends and family. As described on page 167, you can use iPhoto to create low-resolution versions of your images.

Where Digital Images Come From

iPhoto can work with digital images from a variety of sources.

Digital camera

Digital cameras are more plentiful and capable than ever. The key factor that differentiates cameras is resolution: how many pixels of information they store in each image. Even inexpensive digital cameras now provide resolutions of between 4 and 6 megapixelsmore than enough to make large prints.

Most digital cameras connect to the Mac's USB port. Images are usually stored on removable-media cards; you can also transfer images into iPhoto by connecting a media reader to the Mac and inserting the memory card into the reader (page 118).

Scanner

With a scanner, you can create digital images from photographs and other hard-copy originals.

Scanners also connect via USB, although some high-end models connect via FireWire. Film scanners are a bit pricier, but can scan negatives and slides and deliver great image quality (page 206). Save your scanned images in JPEG format, and then add them to iPhoto by dragging their icons into the iPhoto window (page 119).

For tips on getting high-quality scans, visit www.scantips.com.

In a digital camera, the image is focused by the lens (A) onto a sensor (B), where tiny, light-sensitive diodes called photosites convert photons into electrons. Those electrical values are converted into digital data and stored by a memory card or other medium (C), from which they can be transferred to a computer or printer.

Compact Disc

For an extra charge, most photofinishers will burn your images on a compact disc in Kodak Picture CD format. You get not only prints and negatives, but also a CD that you use with the Mac.

To learn more about Picture CD, go to www.kodak.com and search for picture cd.

Internet

Many photofinishers also provide extra-cost Internet delivery options. After processing and scanning your film, they send you an email containing a Web address where you can view and download images. After downloading images, you can drag their icons into iPhoto's window.

A Short Glossary of Imaging Terms

artifacts Visible flaws in an image, often as a result of excessive compression or when you try to create a large print from a low-resolution image.

CompactFlash A removable-memory storage medium commonly used by digital-cameras. A CompactFlash card measures 43 by 36 by 3.3 mm. The thicker Type 2 cards are 5.5 mm wide.

compression The process of making image files use less storage space, usually by removing information that our eyes don't detect anyway. The most common form of image compression is JPEG.

EXIF Pronounced ex-if, a standard file format used by virtually all of today's digital cameras. EXIF files use JPEG compression but also contain details about each image: the date and time it was taken, its resolution, the type of camera used, the exposure settings, and more. iPhoto retrieves and stores EXIF information when you import images. EXIF stands for Exchangeable Image File.

JPEG Pronounced jay-peg, the most common format for storing digital camera images. Like MP3, JPEG is a lossy compression format: it shrinks files by discarding information that we can't perceive anyway. And as with MP3, there are varying degrees of JPEG compression; many imaging programs enable you to specify how heavily JPEG images are compressed. Note that a heavily compressed JPEG image can contain artifacts. JPEG stands for Joint Photographic Experts Group.

megapixel One million pixels.

pixel Short for picture element, the smallest building block of an image. The number of pixels that a camera or scanner captures determines the resolution of the image.

raw An image containing the data captured by the camera's light sensor, with no additional in-camera image processing applied (see page 154).

resolution 1. The size of an image, expressed in pixels. For example, an image whose resolution is 640 by 480 contains 480 vertical rows of pixels, each containing 640 pixels from left to right. 2. A measure of the capabilities of a digital camera or scanner.

SmartMedia A commonly used design for removable-memory storage cards.




The Macintosh iLife '06
The Macintosh iLife 06
ISBN: 0321426541
EAN: 2147483647
Year: 2004
Pages: 229
Authors: Jim Heid

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