A digital on-screen graphic (originally known as digitally originated graphic, and known in the UK and New Zealand by the acronym DOG; in the US, Canada, Ireland, and Australia as a bug or network bug) is a watermark-like station logo that most television broadcasters overlay over a portion of the screen area of their programs to identify the channel. They are thus a form of permanent visual station identification, increasing brand recognition and asserting ownership of the video signal.
The graphic identifies the source of programming, even if it has been time-shifted—that is, recorded to videotape, DVD, or a digital personal video recorder such as TiVo. Many of these technologies allow viewers to skip or omit traditional between-programming station identification; thus the use of a DOG enables the station or network to enforce brand identification even when standard commercials are skipped.
DOG watermarking helps to reduce off-the-air copyright infringement—for example, the distribution of a current series' episodes on DVD: the watermarked content is easily differentiated from "official" DVD releases, and can help identify not only the station from which the broadcast was captured but usually the actual date of the broadcast as well.
Graphics may be used to identify if the correct subscription is being used for a type of venue. For example, showing Sky Sports within a pub requires a more expensive subscription; a channel authorized under this subscription adds a pint glass graphic to the bottom of the screen for inspectors to see. The graphic changes at certain times, making it harder to counterfeit.
On the other hand, watermarks pollute the picture, distract viewers' attention, may cover an important piece of information presented in the television program. Extremely bright watermarks may cause screen burn-in on some types of TV sets.
Usage of visually perceptible embedded watermarks requires program author to have a separate clean copy for archival purposes, but this practice was not common decades ago when watermarking became popular among broadcasters. Watermarks present an issue when archival videos are used for a documentary that strives to create a coherent story. In some cases, watermarks are blurred or digitally removed if possible to clean up the picture. In the absence of visually perceptible watermarks, content control can be ensured with visually imperceptible digital watermarks.
In some cases, the graphic also shows the name of the current program. Some television networks use an on-screen graphic to advertise upcoming programs (usually programs scheduled later the same day, but also for "significant" upcoming programs as much as a week in advance).
Many news broadcasters, as well as a few television networks in such cases, also place a clock alongside their bug. In the United States, Canada, Australia, and New Zealand, DOGs may also include the show's parental guideline rating. In Australia, this is known as a Program Return Graphic (PRG). It has become common to place text above the station's logo advertising other programs on the network.
In many countries, some TV networks put "live" at the bottom of the DOG to advise viewers that the program is live, as opposed to a repeat.
During televised sports events, a DOG may also display a few game-related statistics such as the current score. This has led many people in Canada and the United States to refer to it as a score bug.