A screenshot (or screen shot), screen capture (or screencap), screen dump, screengrab (or screen grab), or print screen[1] is an image taken by the computer to record the visible items displayed on the monitor, television, or another visual output device. Usually this is a digital image taken by the host operating system or software running on the computer, but it can also be a capture made by a camera or a device intercepting the video output of the display (such as a DVR).
Screenshots can be used to demonstrate a program, a particular problem a user might be having or generally when display output needs to be shown to others or archived.
Contents |
[edit] Built-in screenshot functionality
[edit] Mac OS X
On Mac OS X, a user can take a screenshot of an entire screen by pressing Command-Shift-3, or of a chosen area of the screen by Command-Shift-4. This screenshot is saved to the user's desktop, with one PNG file per attached monitor.
Beginning with Mac OS X Leopard, it is possible to make a screenshot of an active application window. By following Command-Shift-4, with pressing the Spacebar, the cross-hair cursor turns into a small camera icon. The current window under the cursor (the small camera icon) is highlighted (the window doesn't need to be on top, just under the camera icon), and a click on the mouse or trackpad will capture a screenshot of the highlighted element (including the parts offscreen or covered by other windows).
A provided application called Grab (located in /Applications/Utilities) will capture a chosen area, a whole window, the whole screen, or the whole screen after 10 seconds (allowing you to 'pose' your mouse actions), and pops the screenshot up in a window ready for copying to the clipboard or saving as a TIFF.
A shell utility called "screencapture" (located in /usr/sbin/screencapture) can be used from the Terminal application or in shell scripts to capture screenshots and save them to files. Various options are available to choose the file format of the screenshot, how the screenshot is captured, if sounds are played, etc. This utility might only be available when the Mac OS X developer tools are installed. A user cannot capture the screen while DVD Player is running.
[edit] Microsoft Windows
On Microsoft Windows, pressing Print Screen captures a screenshot of the entire desktop and places it in the clipboard, while Alt+Print Screen captures only the active window. In most versions of Windows, captured screenshots do not include the mouse pointer.
Once captured, the screenshot must be pasted from the clipboard into a separate program, such as Paint or GIMP, in order to be viewed or saved. Some programs, however, particularly multiplayer online games, will automatically save screenshots in a specified folder. As of Windows XP (or any version based on Windows NT), it is no longer possible to take screenshots of full-screen DOS windows without other software.
Video content in programs using a hardware overlay video renderer is not captured by the method described above.[2] Windows Media Player on Windows XP in its default configuration on supported hardware is affected by this. However, some third-party applications can capture overlay images.
Windows Vista and Windows 7 include a utility called Snipping Tool, first introduced in Windows XP Tablet PC Edition. It is a screen-capture tool, that allows for taking screenshots (called snips) of windows, rectangular areas, or a free-form area. Snips can then be annotated, saved as an image file or as an HTML page, or emailed. However, it does not work with non-tablet XP versions but represents an XP compatible equivalent. Windows 7 also provides a "problem steps recorder" (psr).[3] This will record a screenshot every time you click on your screen. When stopped it creates a zipped MHTML document with all the screenshots inside.
For programmatic access, application developers can use GDI, DirectX or the Windows Media Encoder API to capture the screen.[4]
[edit] iOS
A screenshot can be taken with the iOS by pressing and holding the Home button and the Sleep/Wake button; the screen will flash and the picture will be stored in PNG format in the "Camera Roll" on the iPhone or in "Saved Photos" on the iPod touch. The screenshot feature is only available with iOS 2.0 and later.
[edit] Palm WebOS
Screenshots of the Palm WebOS can be taken by simultaneously pressing "Orange Key + Sym + P". Screenshots will be saved to your "Screen captures" folder in the "Photos" app.
[edit] Maemo 5
On Maemo 5 a screenshot can be taken by pressing "Ctrl + Shift + P" simultaneously. Screenshots will be saved as "Screenshot-YYYYMMDD-HHMMSS.png" in "Images/Screenshots" on the internal storage.
[edit] X Window System
Since X Window System itself is not a desktop environment and only includes a very basic set of programs, methods of taking screenshots vary greatly on the platform. While xwd(1) is the closest "standard" way to do it in the X Window System, most people use other bundled utilities to achieve the task due to their ease of use.
- xwd On systems running the X Window System the standard utility to dump an image of an X Window is xwd(1), xwd produces an XWD image.
- import is a command line tool that is part of the ImageMagick suite, and captures screenshots in a variety of formats.
- KSnapshot is the default screen grabbing utility in the K Desktop Environment.
- gnome-screenshot is the default screen grabbing utility in GNOME.
- Shutter is a feature-rich screenshot program.
Additionally, using KDE or GNOME the Print Screen key behaviour is quite the same as it is on Windows. It is very easy to take screenshots with the image editing program GIMP, if it is available.
[edit] Third-party tools
- Capture Assistant
- Greenshot
- IrfanView
- Jing
- Lightscreen
- Lightshot
- Microsoft OneNote
- PrintKey 2000
- SnagIt
- Snapz Pro X
- Snipping Tool
- Softario Captus
- VVCap
- Window Clippings
- ZScreen
[edit] Common technical issues
[edit] Hardware overlays
On Windows systems, screenshots of games and media players sometimes fail, resulting in a blank rectangle. The reason for this is that the graphics are bypassing the normal screen and going to a high-speed graphics processor on the graphics card by using a method called hardware overlay. Generally, there is no way to extract a computed image back out of the graphics card, though software may exist for special cases or specific video cards.
One way these images can be captured is to turn off the hardware overlay. Because many computers have no hardware overlay, most programs are built to work without it, just a little slower. In Windows XP, this is disabled by opening the Display Properties menu, clicking on the "Settings" tab, clicking, "Advanced", "Troubleshoot", and moving the Hardware Acceleration Slider to "None."
Free software media players may also use the overlay, but often have a setting to avoid that, or dedicated screenshot functions.
Mac OS X DVD player deactivates the built-in screenshot feature, but it is still possible to capture the image or the video with third party software, or by using the "screencapture" command in the terminal.
[edit] Screen recording
The screen recording capability of some screen capture programs is a time-saving way to create instructions and presentations, but the resulting files are often large.
A common problem with video recordings is the action jumps, instead of flowing smoothly, due to low frame rate. Though getting faster all the time, ordinary PCs are not yet fast enough to play videos and simultaneously capture them at professional frame rates, i.e. 30 frame/s. For many cases, high frame rates are not required. This is not generally an issue if simply capturing desktop video, which requires far less processing power than video playback, and it is very possible to capture at 30 frame/s. This of course varies depending on desktop resolution, processing requirements needed for the application that is being captured, and many other factors.
[edit] Copyright issues
Some companies believe the use of screenshots is an infringement of copyright on their program, as it is a derivative work of the widgets and other art created for the software.[5][6] Regardless of copyright, screenshots may still be legally used under the principle of fair use in the U.S. or fair dealing and similar laws in other countries.[7][8]
Preventing copying is one of the issues that Trusted Computing seeks to address. Under Trusted Computing, the user would be prevented from taking screenshots when certain programs are running.
[edit] See also
- Comparison of screencasting software
- List of screencasting software
- Screencast
- Screenshot map
- Thumbshot
- Video capture
[edit] References
- ^ Motive.co.nz
- ^ Hardware Overlays Knowledge Base
- ^ Windows.microsoft.com
- ^ Various methods for capturing the screen
- ^ "Screen Shots (Excluding Xbox)". Use of Microsoft Copyrighted Content. http://www.microsoft.com/about/legal/permissions//default.mspx#E3C. Retrieved 2007-08-22.
- ^ "Question: What are screenshots, and is using them copyright infringement?". FAQ about Copyright -- Chilling Effects Clearinghouse. http://www.chillingeffects.org/copyright/faq.cgi#QID809. Retrieved 2007-08-22.
- ^ "Copyright in screenshots? Who owns it?". MetaFilter. http://ask.metafilter.com/55616/Copyright-in-screenshots-Who-owns-it. Retrieved 2007-08-22.
- ^ "Ask the Law Geek: Is publishing screenshots Fair Use?". Lifehacker. http://lifehacker.com/software/ask-the-law-geek/ask-the-law-geek-is-publishing-screenshots-fair-use-193343.php. Retrieved 2007-08-22.