Changes

'''Overscan''' is the term used to describe the situation when not all of a televised image is present on a viewing screen. It exists because television sets from the 1930s through the 1990s were highly variable in how the video image was positioned within the borders of the cathode ray tube (CRT) screen. The solution was to have the monitor show less than the full image i.e. with the edges "outside" the viewing area of the tube. In this way the image seen never showed black borders caused by either improper centering or non-linearity in the scanning circuits or variations in power supply voltage all of which could cause the image to "shrink" in size and reveal the edge of the picture. With the ending of CRT displays, this issue has largely (but not completely) disappeared.

Computer CRT monitors usually have a black border (unless they are fine-tuned by a user to minimize it)—these can be seen in the video card timings, which have more lines than are used by the desktop. When a computer CRT is advertised as 17-inch (16-inch viewable), it will have a diagonal inch of the tube covered by the plastic cabinet; this black border will occupy this missing inch (or more) when its geometry calibrations are set to default (LCDs with analog input need to deliberately identify and ignore this part of the signal, from all four sides).

Video game systems have been designed to keep important game action in the title safe area. Older systems did this with borders for example, the [[Super Nintendo emulators|Super Nintendo Entertainment System]] windowboxed the image with a black border, visible on some NTSC television sets and all PAL television sets. Newer systems frame content much as live action does, with the overscan area filled with extraneous details.<ref name="caminos">{{cite web|url= https://web.archive.org/web/20111219084409/http://www.gamasutra.com/gdc2004/features/20040326/caminos_01.shtml |title=GDC 2004: Cross-Platform User Interface Development |publisher=Gamasutra |year=2004 |accessdate=2012-02-09 }}</ref>