AB - Computer wallpaper - photo wallpapers: The terms wallpaper and desktop picture refer to an image used as a background on a computer screen, usually for the desktop of a graphical user interface. 'Wallpaper' is the term used in Microsoft Windows, while the Mac OS calls it a 'desktop picture' (prior to Mac OS X, the term desktop pattern was used to refer to a small pattern that was repeated to fill the screen). Images used as computer wallpaper are usually raster graphics with the same size as the display resolution (for example 1024×768 pixels, or 1280×1024 pixels) in order to fill the whole background. Many screen resolutions are proportional, so an image scaled to fit in a different-sized screen will often be the correct shape, albeit that scaling may impact quality. PNG and JPEG format are common. Users with widescreen (16:9 or 16:10) monitors have different aspect ratio requirements for wallpaper, although images designed for standard (4:3) monitors can often be scaled or cropped to the correct shape without loss of quality. Wallpapers are sometimes available in double-width versions (e.g. 2560×1024) for displaying on multi-monitor computers, where the image appears to fill two monitors. Some display systems allow unconventionally-proportioned images (1:1, 2:1, or even 1:3) to be scaled without change of proportion, to fit the screen, whether it be 16:9 or 4:3. The image would be sized just large enough that one pair of edges touch the edges of the screen, but not all four, as this would unduly distort the image. Most display systems are capable of specifying a single-colour to use as the background in place of a wallpaper, and some (such as KDE or GNOME) allow colour-gradients to be specified. Microsoft Windows 3.x and 9x systems allow using editable repeating two-color 8×8 tiles for background. Some desktop systems, such as Mac OS (version 8.6 or later), KDE (version 3.4 or later), and GNOME, support vector wallpapers (PICT in Mac and SVG in KDE and GNOME). This has the advantage that a single file may be used for screens of any size, or stretched across several screens, without loss of quality. The first use of a distinguishable background in conjunction with overlapping windows was in an experimental office system, Officetalk, developed in 1975 at Xerox PARC on the Alto. Prior to that, the white backgrounds to overlapping windows (for example, in Smalltalk) could be difficult to distinguish from window interiors. The pattern used in Officetalk produced a 25% gray, using dots two pixels high to avoid flicker on the Alto's interlaced screen. The same pattern was adopted for the Xerox Star. Apple used a similar gray background for their Lisa and Macintosh. However, since these machines had non-interlaced screens it was possible to use a less noticeable background pattern, formed from a simple 2x2 repeating pattern that gave a 50 percent gray. The introduction of color monitors for personal computers led to non-patterned, single-color backgrounds and then to arbitrary 'wallpapers'. Wallpaper styles are as varied as people themselves, using photographs, drawings, 3D renders or abstract pattern with complex gradients. It can be useful to have plain areas so that icons can be clearly seen atop the wallpaper. Typical categories can include cars, models and celebrities, scenery, abstract art, movies, pets, family, symmetry, and personal photos. In business use, corporate logos or plain backgrounds are often specified by the companies' guidelines. When using rack mounted computers through a KVM switch, it can often be useful to create a wallpaper with the computer's name on it, to easily identify which computer you're connected to. Some operating environments (e.g. KDE and Mac OS X) allow a number of different wallpapers to be used, and "rotated" to display a different wallpaper at different times, to display a random image from a directory. If the facility is not available in the OS' wallpaper settings, it may be possible to get an external program which can change the wallpaper at certain times. Microsoft Windows 98 and higher allow webpages to be set as frames on the desktop which may be dynamic pages. Programs such as Xplanet and EarthDesk use Internet connections and graphics calculations to change the wallpaper with real data, such as a shadowed view of the earth, the latest cloud or weather map, or various events. Some media players can redirect video playback to desktop, allowing any video to be used as a wallpaper. Other tools (for example WireChanger) can add interactive widgets to a wallpaper, such as calendar, notes, RSS feed, or generate a wallpaper image using various algorithms. Macromedia/Adobe Flash animated movies and games can be set a dynamic interactive background as well. Point your desktop background settings to an html file with embedded flash movie instead of an image.