BT709standardeissa

BT709standardeissa, often referred to as BT.709 or simply Rec. 709, is a standard that defines high-definition television (HDTV) system parameters. Developed by the International Telecommunication Union Radiocommunication Sector (ITU-R), it was first published in 1990. The primary purpose of BT.709 is to establish a common set of specifications to ensure interoperability between different HDTV broadcasting systems and display devices worldwide.

The standard specifies several key aspects of an HDTV signal. It defines the image aspect ratio as 16:9, a significant departure from the 4:3 aspect ratio prevalent in standard-definition television. BT.709 also specifies the picture resolution, typically 1920 pixels horizontally by 1080 pixels vertically, often denoted as 1080i or 1080p depending on the scanning method. Furthermore, it outlines the color space, which is based on the CIE 1931 colorimetric system and uses the primary color coordinates of red, green, and blue. The standard also details the gamma correction curve, which determines the relationship between the digital signal values and the luminance displayed on screen.

BT.709 has become the de facto standard for HDTV production and transmission across much of the globe. Its adoption has facilitated the transition to higher image quality and has been instrumental in the development of modern television broadcasting. While newer standards exist for even higher resolutions like 4K (Rec. 2020), BT.709 remains a fundamental reference point in digital video technology.