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You can save a screen capture as a file or just paste it from the clipboard.
 technofile
Al Fasoldt's reviews and commentaries, continuously available online since 1983

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Capturing screen shots in Mac OS X


Feb. 12, 2006


By Al Fasoldt
Copyright © 2006, Al Fasoldt

   Mac OS X computers are far ahead of Windows PCs in the way screen images are captured as screen shots.
   Apple, which makes the popular Mac OS X computers, provides ways to capture all or just part of the screen. And you have a further choice of a fully formed image -- a picture that shows up on your desktop -- or a hidden image stored in the clipboard, ready for you to paste it into a document or an image program.
   Unlike Windows, which relies on the Print Screen key to make screen shots, Apple's Macintoshes use key combinations that are all based on the Macintosh Command key, usually written in abbreviated form as Cmd. It's the key that has the four-cornered clover-like symbol on all modern Macintosh keyboards. (On older ones, it has an Apple symbol. Old-time Mac users sometimes call it the "Apple key" for that reason.)
   To take a picture of the entire screen, hold down Cmd and Shift and press 3. The image will show up on your desktop within a file called "Picture 1." Additional screen shots will be placed on the desktop in files called "Picture 2," "Picture 3" and so on. Double click any "Picture" file to view it in Preview, the Mac OS X image viewer. You can also drag the image file into iPhoto to view it there.
   To take a picture of just part of the screen, hold down Cmd and Shift and press 4, then click your mouse and drag it around the area you want to capture. Click once to make the screen shot.
   To take a picture of an object on the screen -- such as a window, the menu bar or the dock -- hold down Cmd and Shift and press 4, then let up and press the Space bar. Move the mouse to the object you want to capture and click the button when it's highlighted.
   These methods produce actual image files. But if you'd rather work with something you can readily paste into a Microsoft Word document, an e-mail message or a photo editor, you should choose the alternative method, which creates a hidden screen shot that's placed on the clipboard.
   To do that, hold down the Ctrl key when you do any of the functions listed above. Then click inside your document window and press Cmd-V to paste the screen shot into the document or e-mail message, or choose the appropriate option from the Edit menu of your photo editor.
   "Picture" files come in two kinds, depending on your version of Mac OS X. Current OS X Macs running the Tiger version of the operating system (OS X 10.4) create PNG ("ping") images. Previous OS X versions create PDF images. Both work well for saving and working with screen shots.
   PNG is a lot like the most common image format, JPEG, except for one helpful difference: PNG images never lose quality. A screen shot stored as a PNG will be exactly the same as what you saw on the screen. (You might not be aware of a huge problem of JPEG images: They're "lossy," meaning they're never able to show an exact representation of any image. But when we've viewing such objects as faces, buildings and trees, our eyes are easily fooled, so we seldom notice JPEG quality losses. But screen shots tend to include a lot of text, which is just the sort of object JPEG processing messes up. So Apple did the right thing in choosing PNG as the screen shot format for OS X.)
   If you have an older OS X Macintosh and find that your screen shots are PDFs, don't feel left out. OS X uses a lossless PDF method and he older method of storing screen shots as PDFs also produces perfectly accurate screen shots, but PDFs aren't as easy to work with as PNGs.
   Apple didn't lock in the screen shot image format. If you'd rather be presented with TIFF files or another kind of graphics format, you can easily change a setting in OS X that governs how screen shots are stored.
   If you're using Tiger, my recommendation is a freeware program called SCIT (Screen Capture Image Type) from www.daniele.ch/downloads.html. For earlier versions of OS X, use Tinker Tool to change the screen shot format. Get Tinker Tool from macupdate.com/info.php/id/5721. (Important: Tinker Tool lets you change many aspects of OS X in both good and bad ways. Don't change anything other than the screen shot format at this time.)