What is High Definition?

High-definition video is video of higher resolution than is standard. While there is no specific meaning for high-definition, generally any video image with more than 480 horizontal lines (North America) or 570 lines (Europe) is considered high-definition. 720 scan lines is generally the minimum even though many systems greatly exceed that. Images of standard resolution captured at rates faster than normal (60 frames/second North America, 50 fps Europe), by a high-speed camera may be considered high-definition in some contexts.

What is SDI?

Signal Document Interface (SDI) In graphical user interfaces, a single document interface or SDI is a method of organizing graphical user interface applications into individual windows that the operating system's window manager handles separately. Each window contains its own menu or tool bar. This contrasts with a multiple document interface, in which a single parent window is used to contain multiple nested child windows, with only the parent window having a menu or tool bar.

Often in single document interfaces, each window is represented as an individual entry in the operating system's task bar or manager. Applications which allow the editing of more than one document at a time, e.g. word processors, may therefore give the user the impression that more than one instance of an application is open. Some task managers summarize windows of the same application. For example, Mac OS X uses a feature called Exposé which allows the user to temporarily see all windows belonging to a particular application.

What is resolution?

Image resolution is the detail an image holds. The term applies to raster digital images, film images, and other types of images. Higher resolution means more image detail. Image resolution can be measured in various ways. Basically, resolution quantifies how close lines can be to each other and still be visibly resolved. Resolution units can be tied to physical sizes (e.g. lines per mm, lines per inch), to the overall size of a picture (lines per picture height, also known simply as lines, TV lines, or TVL), or to angular subtenant. Line pairs are often used instead of lines; a line pair comprises a dark line and an adjacent light line. A line is either a dark line or a light line. A resolution 10 lines per millimeter means 5 dark lines alternating with 5 light lines, or 5 line pairs per millimeter (5 LP/mm). Photographic lens and film resolution are most often quoted in line pairs per millimeter.