Screenshot

File:Screenshot of Wikipedia Screenshot Page.png

A screenshot of the Wikipedia website being displayed in the Mozilla web browser.

A screenshot, screen dump, or screen capture is an image taken by the computer to record the visible items on the monitor or another visual output device. Usually this is a digital image taken by the host operating system or software running on the computer device, but it can also mean when a capture is made by an external device such as a camera or something intercepting the video output of the computer.

Screenshots, screen dumps, or screen captures can be used to demonstrate a program, a particular problem a user might be having or generally when computer output needs to be shown to others or archived.

All three terms are often used interchangeably; however, some people distinguish between them as follows:

Screenshot

Outputting the entire screen in a common format such as PNG or JPEG.

Screen dump

The display system dumps what it is using internally upon request, such as XWD X Window Dump image data in the case of X11 or PDF in the case of Mac OS X. As of Mac OS X 10.4, pictures are no longer saved as PDF. They are saved as PNGs.

Screen capture

Capturing the screen over an extended period of time to form a Video file.

Taking screenshots

There are numerous ways to take a screenshot on many operating systems, and applications. This article attempts to cover the ones that use standard software on each platform to achieve the task.

Mac OS

In all versions of Mac OS up through (and past) Mac OS 9 the user simply hits ⇧⌘3 (shift-apple key-3), this puts a PICT file of the screen on the desktop. ⇧⌘4 allows the user to make a marquee selection of the screen. The screen capture is accompanied by a sound effect of a camera shutter as it takes a picture (Grab, detailed below, continues this tradition).

Mac OS X

Mac OS X offers several means to take a screenshot. ⇧⌘3 & ⇧⌘4 (shift-apple key-3/4) both work, however there are more options. The application Grab supports 2 more options, window selection and timed screen capture. Preview version 3 (Mac OS X v10.4) now has an option to take window, selection and timed screen captures. Both Grab & Preview automatically save the files as TIFF. Screenshots taken by ⇧⌘3 are saved in the system default format, varying from version to version of Mac OS X. This can be changed on the command line using defaults (or the 3rd party TinkerTool, file options are: BMP, GIF, JPEG 2000, JPEG, PDF, PICT, PNG, PSD, SGI, TGA & TIFF.). Screenshots cannot be taken while protected DVDs are playing in DVD Player.

Microsoft Windows

In Microsoft Windows a screenshot of the entire monitor, complete with taskbar, can be copied to the system clipboard by pressing the Print screen key. Alternatively, pressing ALT + Print Screen will copy just the active window to the clipboard. You can then paste the clipboard into a program like MS Paint or Paint.NET to save it as an image file (for posting online, for instance), or paste it directly into a document.

Hardware overlays

Screenshots of games and media players sometimes fail, resulting in a blank rectangle. What's happening is the graphics are bypassing the normal screen and going to a high-speed graphics processor on your graphics card called the hardware overlay. Generally, there's no way to extract a computed image back out of the graphics card, though software may exist for special cases or specific video cards.

The trick to capturing those images 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.

There are two ways to turn off the overlay. The usual way is to turn it off in the settings for the specific game or media player. Instructions for Windows Media Player, QuickTime, RealPlayer and Winamp are here.

One can also turn off the hardware overlay globally through Windows as shown here. On Windows XP, go to Display Properties > Settings Tab > Advanced Button > Troubleshoot Tab. Set the Hardware Acceleration slider to one of the first three notches.

Store bought DVDs are a special case because they're encrypted using a patented algorithm called Content-scrambling system (CSS). Many DVD-capable media players (including Windows Media Player), but not all (PowerDVD, WinDVD, to name two), will only play DVDs on the overlay layer, where they can't be captured. For a review of which media players are best for screen capture, go here.

Scroll capture

Often a page or list doesn't show on your screen all at once, you must scroll to see it all. To capture those areas intact, use the scroll capture tool offered by some vendors. This tool captures the entire page or list, automatically scrolling vertically and/or horizontally as required.

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. For tips on managing the file size, with examples of the effects of each setting, go here. The professional way to create small, efficient demos is to build them from scratch in a Macromedia Flash editor, such as SwiSH Max., but this takes much more work.

Some sophisticated screen recording programs minimize file size by capturing only frames that change. In practice, you end up manually adding frames and doing other editing, so these programs fall mid-spectrum between simple recorders and building from scratch. One popular screen recording application that makes use of this is Camtasia Studio, by means of the proprietary TSCC codec.

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 frames/s. This of course varies depending on desktop resolution, processing requirements needed for the application that is being captured, and many other factors. For tips on maximizing frame rates, go here. For those who must have frame rates of 30 or above, one safe solution (though lower in overall quality) is to point a camcorder at the screen or to record on a VCR connected to the TV-Out on your graphics card.

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. It can be invoked in the following way:

xwd -root -out root.xwd

xwd can also be used to dump a single window if provided with the -id option followed by the corresponding window id, for further info see man 1 xwd [1]. When run remotely, xwd is useful for taking screen shots of modal menus in action. The GIMP can be used to convert an XWD file to other more common formats such as PNG.

KDE and GNOME

In the K Desktop Environment, the built-in program KSnapshot is the default screen grabbing utility.

GNOME users can take a screenshot either by selecting "Take Screenshot..." from the "Actions" menu (in GNOME versions older than 2.10), by selecting "Take Screenshot" from the "System..." menu (GNOME 2.10 or greater) or by using one of the following two keyboard shortcuts:

• Print Screen, to take a screenshot of the entire screen, or
• Alt + Print Screen, to take a screenshot of the currently active window.

This can also be configured in Preferences → Keyboard Shortcuts.

Screenshot software

There are many third-party programs available on different platforms to take screenshots with advanced functionality. Most computer graphics software (e.g., IrfanView, GIMP, and Photoshop) can acquire screenshots. Typically, these programs can be configured to include or exclude the mouse pointer, automatically crop out everything but the client area of the active window, take timed shots, areas of the screen not visible on the monitor (autoscroll), and so on.

Copyright issues

Some companies believe the use of screenshots is an infringement of copyright on their program. This is one of the issues "solved" by Trusted Computing. Under Trusted Computing, programs will be able to block the taking of screenshots of their windows. Countering this argument is the principle of fair use, which (in U.S. law) permits copying of images or text for 'criticism, comment, news reporting, teaching, scholarship, or research.'

See also

• Screenshot map
• Thumbshot

External links

• Desktop Rating - Submit screenshots and have them rated by others.
• WritersUA - Review of Screen Capture Tools (Updated December 2005)

Software

Third-party tools aren't required, but they make the process faster and easier. The better tools also enable you to capture scrolling pages, the mouse pointer, audio and video. Some examples include:

• PrntScrn.NET - A completely free Screen Capture program with integrated image uploading.
• Virtual Screen Spy - Screen Capture Software for Windows.
• FullShot - A screenshot application for Windows.
• CaptureWizPro - Windows utility for capturing screen images, scrolling areas, audio and video.
• Simple Screenshot - A simple and free screenshot program for Windows.
• DemoStudio - GPL program for recording software demonstrations, like Camtasia Studio.
• WordScale - Enables third party programs to capture Editable Text directly from the screen.
• Paparazzi - Allows you to capture the entire contents of a Safari web browser window (including that which you normally have to scroll to see). Free for OSX.
• WSnap - A simple Windows screenshot application.
• SnagIt - The Leader in Screen Capture
• Screenshot Plus - A free widget for the Mac OS X Dashboard
• Girafa.com - Free thumbnail images of websites.