MacDevCenter    
 Published on MacDevCenter (http://www.macdevcenter.com/)
 See this if you're having trouble printing code examples


Screenshot Hacks for Mac OS X

by Wei-Meng Lee and Derrick Story
02/28/2003

Capturing great screenshots in Mac OS X involves a little adventure. If you simply want to capture something on your monitor for reference later on, you can do that easily with the built-in screen capture tool. However, if you are a professional writer (or a student preparing an important report) and need great-looking screenshots, you have to spend a little more time exploring your options.

What if you want to capture moving pictures from your screen, such as a QuickTime video clip or a scene from a DVD movie, as well? With a little ingenuity, you can elevate your screen-capture prowess to grab just about anything that appears on your monitor, moving or not. Here are a few tips how.

Built-in Screenshot Capabilities: The Basics

Mac OS X comes with built-in capability for capturing screen shots. To capture the entire screen, you can simply press Command-Shift-3.

To capture a region of the screen, press Command-Shift-4, then click and drag the cursor to mark the area you want to capture. When you lift your finger from the mouse button, Mac OS X will record that real estate and place a .pdf file on your desktop.


Screen shot.
Figure 1. Capturing a portion of the screen.

While the built-in screen capture tool is good enough for most purposes, it has the following drawbacks:

Using Grab for More Functionality

Mac OS X also ships with the Grab utility, located in the Applications -> Utilities folder. To use Grab, double-click on its icon and choose the type of image you want to capture.

Screen shot.
Figure 3. Using Grab for screen capture.

Grab supports three modes of screen capture:

Surprisingly, the fourth mode, Window capture, is not functional in Jaguar.

Unlike the built-in screen capture utility, Grab allows mouse pointers to be captured. You can capture actions like clicking on a menu item by using the Timed Screen mode, as shown in Figure 4.

Screen shot.
Figure 4. Using the Timed Screen mode to capture actions.

There is one problem that I noticed with Selection mode. In order to capture an active window using Selection mode, you need to switch to Grab first. Doing so makes the window inactive. Now, when I do a Selection grab, I would want to capture the window in the active state. To make the window active, you can right-click on the window and perform your capture. This technique will not work all the time. In particular, I have problems in capturing the System Preferences window using this technique.

Screen shot.
Figure 5. Unable to save the active System Preferences window.

The selection grab will also display the size of the image you are capturing at the bottom right corner of the selection region. This is useful if you need to capture images of an exact size. One gripe I have, though, is over Grab's inability to reposition the selection region.

Unlike the built-in screen capture utility in Mac OS X Jaguar, Grab saves the images in .tiff format.

Mac OS X Hacks

Related Reading

Mac OS X Hacks
100 Industrial-Strength Tips & Tricks
By Rael Dornfest, Kevin Hemenway

One cool feature in Grab is the option to include different mouse pointers (or simply hide the mouse pointer) in the screen capture. To activate this feature, click on Grab -> Preferences. A window containing all of the different mouse pointers will be shown, as in Figure 6.

Screen shot.
Figure 6. Grab allows you to capture mouse pointers.


Screen shot.
Figure 7. Capturing the mouse pointer with Grab.

Saving a Large Document that Spans Many Screens

What if you want to save a big document, such as a long HTML page, that spans many screens on your monitor? An easy method, that's built right into Mac OS X, is to convert it the page to a .pdf file.

Go to the File menu and then choose Print. At the bottom of the Print dialogue box, you will see a button that reads Preview. Click it and it will process your document and open the Preview application that's included with Mac OS X.

You'll notice that when your document is displayed in the Preview application (or sometimes in Adobe Acrobat), it already looks like a .pdf file. Now all you have to do is choose File, then Save As PDF, and Mac OS X will convert your entire document into a real live multi-page .pdf document.

This is much easier than using Grab to save multiple screens, and then have to keep them in the proper order.

Using Snapz Pro X

The ultimate screen capture utility for Mac OS X is Snapz Pro X from Ambrosia Software, Inc. It provides you with a variety of options for grabbing information from your screen.

For example, to capture a simple screen shot, press Command-Shift-3 (this keystroke combination is customizable). The screen will be frozen, and you will see the window as shown in Figure 8.

Screen shot.
Figure 8. Choosing the type of items to capture.

Then choose your options, and hit the Return key. Your options are:

Keep in mind that you can capture still images in all of these formats: .bmp, .gif, .jpg, .pdf, .pict, .png, .psd, and .tiff. But you have to set this option before the screen capture takes place. Otherwise, you'll have to open the screenshot in an image editor to change the format.

For a "selection capture," Snapz allows you to mark out and position the region you want to grab. Double-clicking on the region, or hitting the Return key, will then capture the screen.

Screen shot.
Figure 9. Capturing a selection of a screen.

One very nice feature is that Snapz Pro X allows you to automatically capture the shadows of a window! Simply change the Border option under Image Options to Drop shadow (as shown in Figure 8). Prior to using Snapz Pro X, I always had to switch the background to white so that I can capture the nice shadow around the window. But no more!

Capture Moving Pictures Too!

One of the really exciting features of Snapz Pro X is its "Movie capture mode," which works for both QuickTime and DVD movies. First, launch the video you want to capture, then enable Snapz. Hit the Return key and Snapz will grab the video as it plays.

Screen shot.
Figure 10. Capturing QuickTime playback.

If you're interested in this function, keep in mind that there are two versions of Snapz Pro X: the $29 and $49 versions. If you want to capture QuickTime and DVD video, make sure you get the $49 version, or you'll be disappointed because this functionality is missing from the $29 version.

Screen shot.
Figure 11. Capturing DVD playback.

Capturing Synchronized Audio with Snapz Pro X Video

When capturing QuickTime, Snapz Pro X only grabs the video because the internal "audio in" option is disabled. This applies to both DVD and to QuickTime movies. There is a workaround, however, to snag the synchronized audio.

You'll need a connecting cord with stereo mini-plugs on both ends. Put one plug into your headphone jack (audio out) on your Mac. Then put the other plug into a sound input connector, such as the Griffin iMic. Set the iMic toggle switch to the right, and make sure that the "iMic audio system" is selected under the Input tab in the Mac OS X Sound preferences panel.

Now enable Snapz's movie capture mode while the DVD is playing. Snapz will temporarily halt the movie and display its option screen. Enable the "Microphone track" option (you'll see the checkbox at the bottom of Snapz's dialog box). Click the Movie icon, position the capture frame, and hit the Return button to begin capture of both sound and audio. You'll have to play with the settings a bit to get the quality you want, but it's really quite decent once you find the right balance.

To get you started with the right settings, here are a few tips:

For more information about sound capture on Mac OS X, see "The Digicam Chronicles: Sound is Half the Picture."

Using screencapture in the Terminal App.

The Terminal application comes with a command-line screen capture utility known as screencapture.

This utility provides capabilities similar to those of Grab. To use it, invoke the Terminal window and type screencapture to see the various options supported:

screencapture
screencapture: illegal usage, file required if not going to clipboard
usage: screencapture [-icmwsWx] [file] [cursor]
  -i      capture screen interactively, by selection or window
            control key - causes screen shot to go to clipboard
            space key   - toggle between mouse selection and
                          window selection modes
            escape key  - cancels interactive screen shot
  -c      force screen capture to go to the clipboard
  -m      only capture the main monitor, undefined if -i is set
  -w      only allow window selection mode
  -s      only allow mouse selection mode
  -W      start interaction in window selection mode
  -x      do not play sounds
  file    where to save the screen capture

To capture the entire screen, type:

screencapture imagefilename.pdf

The image will be saved as imagefilename.pdf.

To capture the screen interactively, type:

screencapture -i imagefilename.pdf

and:

Screen shot.
Figure 12. Capturing a screenshot of a window.


Screen shot.
Figure 13. Capturing a screen shot of a region.

Wrapping Up

As you can see, there are many options in Mac OS X for capturing images from your screen and saving them to your hard disk. For most tasks, the free utility Grab or enabling screencapture in the Terminal application should suit your needs. But if you want that professional touch, or are interested in audio/video capture, then take a look at the $49 version of Snapz Pro X.

Wei-Meng Lee (Microsoft MVP) http://weimenglee.blogspot.com is a technologist and founder of Developer Learning Solutions http://www.developerlearningsolutions.com, a technology company specializing in hands-on training on the latest Microsoft technologies.

Derrick Story is the author of The Photoshop CS4 Companion for Photographers, The Digital Photography Companion, and Digital Photography Hacks, and coauthor of iPhoto: The Missing Manual, with David Pogue. You can follow him on Twitter or visit www.thedigitalstory.com.


Return to Mac DevCenter.

Copyright © 2009 O'Reilly Media, Inc.