The term HDTV Televisions were first used to refer to television standards developed in the 1930s to replace early experimental systems with as few as 12 lines. Over the years high definition television has grown to present up to 1080 lines of scanning and in some instances, extreme versions have as many as 1440 lines of resolutions.
A High Definition TV or HDTV allows users to enjoy digital TV broadcasts and other additional features that were not available when analog Television was first introduced. Some benefits of HD Televisions are the ability to view more than one program on the same channel, the ability to acess additional content including electronic program guides, languages and subtitles.
Progressive Scanning, Frames Rates
One of the key factors that influence the way HD Televisions are able to display content and pictures is progressive scanning and frame rates. Progressive scanning is defined as non-interlaced scanning of moving images that allows the HDTV or display system to display, store and transmit moving images in a way that all the lines of every frame are drawn in a specific sequence. In a progressively scanned picture or image, on any kind of HDTV or display, even- and odd-numbered line fields in an image line are flashed and displayed as a single frame. This happens at a speed of one 30th of a second. This in a nutshell means that the progressive scanned image does not flicker as some images do on analogue TV sets, which used interlaced scanning systems and flickered. This anti-flickering allows the HD Televisions to produce and display pictures that are smoother, more detailed and have less lines and flickering.
Frames also play an integral part in the effectiveness of progressive scanning. For example a 1080p is displayed at 30 frames per second. The frame rate is defined as the number of video frames per second. For most marketing purposes, the frame rate is dropped and can sometimes be used individually without a resolution. Cinemas display films at 24p which is 24 frames progressively per second.
In comparison to interlaced scanning which was used quite extensively in analogue and standard-definition TVs. Today a lot of HD Televisions and multimedia systems use progressive scanning, from many film production companies to electronics companies that develop DVD players, Blu-ray and others.
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