HD television (High Definition television) is a video that has a resolution that is substantially higher than that of standard television systems. Typically, HD television has one to two million pixels in its picture per frame, around five times as many pixels as standard television. This article looks at HD television in more detail.
The term 'high definition' is a term that has been used throughout the history of television and is a term that is interpretative of the time that it is used in. For example, the BBC claims to be the first high definition broadcaster when they began transmitting their own high definition television in 1936. These pictures were high definition compared to the television that had been broadcast before this time. However, in modern times, this definitely is not considered to be HD. High definition, as we know it today (August 2011), was launched in the U.K in 2009 and was launched through the new DVB- T, otherwise known as freeview.
What makes a broadcast high definition?
What exactly is HD? High definition is defined by three major parameters: the frame size of the picture, the scanning system used and the pictures frame rate. The frame size in pixels is defined as number of horizontal pixels × number of vertical pixels. Often, the number of horizontal pixels is implied from context and is omitted, as in the case of 720p and 1080p. The scanning system is identified by the letter P for progressive scanning and I for for interlaced scanning. Frame rate is identified as number of video frames per second. For interlaced systems, an alternative form of specifying number of fields per second is often used. For high definition television, the number of frames per second is very high, The following formulae, which you will find examples of on all HDTV sets, can be used to identify which type of HD TV that you have. '1920×1080p25' - the 1920, is the number pixels wide and the 1080 is the pixels high. The p stands for progressive scanning and the 25 stands for the number of frames the television transmits per second.
What is HD Ready? The 'HD Ready' term usually refers to any display that is capable of accepting and displaying a high-definition signal at either 720p, 1080i or 1080 (using a component video or digital input). Essentially, HD Ready refers to a television that is set up to receive HD television, even if the consumer is not yet receiving it.