HD is the abbreviation of English High Definition, which refers to an image or video with a vertical resolution greater than or equal to 720. It is also called high-definition image or high-definition video, and its dimensions are generally 1280×720 and 1920× 1080. The full name of "high definition" is "high definition".
720P and 1280P are the same, 1280 is the resolution, and the correct one is 1280*720. 720p is another way of saying it. However, the two are only different in pixels. Relatively speaking, 1080P is suitable for large LCD TVs, 720P is suitable for ordinary LCD TVs, and 1280P is clearer than 720P.
Blu-ray Disc is named because it uses a blue laser beam with a wavelength of 405 nm to read and write (DVD uses a red reader with a wavelength of 650 nm, and CD uses a wavelength of 780 nm). A single-layer Blu-ray disc has a capacity of 25 or 27GB, which is enough to record a high-resolution movie for up to 4 hours. On February 19, 2008, Toshiba, the leader of HD DVD, announced that it would quit all HD DVD-related businesses at the end of March, and the dispute over the format of the next-generation optical disc, which lasted for many years, officially came to an end. In the end, Blu-ray disc led by SONY won. Blu-ray disc uses YCbCr color and space, adopts 4:2:0 chroma subsampling, and the color depth is 8bit.
HD means that the vertical resolution of the picture is 1080i, 720p or 1080p. 1080i means that the resolution is 1920* 1080, and interlaced scanning is adopted to present 30 complete pictures per second; 720p means that the resolution reaches 1280*720, and it adopts sequential scanning to present 60 complete pictures per second; 1080p means that the resolution reaches 1920* 1080, and it adopts progressive scanning, presenting 60 complete pictures per second. However, the resolution of thin-panel TVs on the market should not be limited to the above styles, as long as the resolution of the display screen is ≥ 1280*720, it can be classified as HD level. Usually, the format with physical resolution above 720p is called High Definition, and the English expression of high definition is HD for short. Full HD refers to progressive scanning with a physical resolution as high as 1920× 1080, that is, 1080p, which is an advanced HD specification.