High Definition Overview
High Definition (HD) is a high-resolution digital television format that creates a new and
powerful visual experience by combining high resolution video with Dolby
Digital 5.1 surround sound (AC-3).
HD Imagines of 720 or 1080 lines of resolution provides significantly more clarity as
compared to the 525 lines of resolution used in the U.S. or the 625 lines of resolution
used in Europe.
The top formats used in HD are:
“I” represents "interlaced" scanning and “P” represents "progressive" scanning. In an interlaced format, the screen shows every odd line at one scan of the screen, and then follows that up with the even lines in a second scan. Since there are 30 frames shown per second, the screen shows one half of the frame every sixtieth of a second. For smaller screens, this is less noticeable. As screens get larger, interlacing will cause the screen to flicker.
Progressive scanning shows the whole picture, every line in one showing, every sixtieth of a second. This provides for a much smoother picture, but uses slightly more bandwidth.