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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, the most common of the three is a screenshot which
commonly means outputting the entire screen in a common format such as PNG or JPEG, a screen dump is when 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. Finally a screen capture commonly means to capture 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.
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 button. Alternatively, pressing ALT + Print Screen will
copy just the active window to the clipboard.
This method does not work with hardware overlays.
Mac OS X
To save an image of the entire screen in Mac OS X pressing Command + Shift +
3 saves a PDF file on the desktop (
~/Desktop/ ) containing a PDF Dump of the screen.
To take a picture of part of the screen pressing Command + Shift + 4 and then select the area to be captured.
To take a picture of a window or menu, press the space bar after Command + Shift + 4. By default, the
captures are stored in PDF on the desktop. To copy
the captures to the clipboard, press the control key along with the other keys.
X Window System
Since the X Window System itself is not a desktop environment and
only includes a very basic set of programs it is not common for the xwd(1) common to be used, most people use other
bundled utilities to achieve the task.
xwd
On systems running the X Window System the standard utility to
dump an image of an X Window is xwd(1), xwd produces XWD X Window Dump image data. 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, wxd is useful for taking screen shots of modal menus in action.
ImageMagick
Alternatively if you have ImageMagick installed the following command can
be used to import the root window and everything above to a PNG image file called
root_window.png, it uses the convert(1) utility, you can
take a screenshot of the entire contents of the screen with this command:
import -window root root_window.png
Alternatively you can use the import command without any arguments, you will then be presented with a cursor with which you
can click on a window and the image generated will contain a image of that window only.
import root_window.png
KDE and GNOME
In the K Desktop Environment, the built-in program KSnapshot is the default screen grabbing
utility. GNOME users can also use the Screen-Shooter applet, choose "Take Screenshot"
from the actions menu or press 'print screen'.
The GIMP
The GIMP can also be used to take screenshots on any platform it is available
on, simply navigate File->Acquire->Screenshot on the toolbox menu to capture either the current screen or choose
timed mode.
See also
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