Ultra-High Definition images and television (UHD)

The main aim of this article is to offer a detailed account of the characteristics of UHD (Ultra-High Definition) video images, and in particular their definition parameters with more pixels (3,840 x 2,160 in UHD-1 and 7,680 x 4,320 in UHD-2), HDR (High Dynamic Range) for a greater contrast range and better representation of brightness differences, WCG (Wide Color Gamut) for a wider color range, and HFR (High Frame Rate) for a higher frame rate. It also provides an overview of the techniques used to produce, distribute and view these images. However, this article does not deal with sound, in particular NGA (Next Generation Audio), which can be associated with UHD.

The development of UHD images is due to several factors:

• the research and development work carried out by Japanese television channel NHK since 1995 with the Super Hi-Vision project [12] ;

• the ongoing quest for superior video and TV image quality;

• pressure from manufacturers to sell ever more new-generation equipment (professional production equipment as well as cameras and digital cameras for home use, along with screens and televisions), by constantly stimulating their renewal;

• the precedent of "2K" or "4K" Digital Cinema, with the missed opportunity to converge on common parameters with video, and the ambiguity of the terms "4K" and "8K" to designate UHD-1 and UHD-2.

Over and above the technical aspects, we still need to develop programs and applications using UHD images, for both professional and consumer applications.