6th Color Imaging Conference

Scottsdale, Ariz., Nov. 17, 1998

Color in Digital Video: DTV, ATV and High Definition Television

Color image coding for video involves classical colorimetry, but it also involves a set of engineering compromises and optimizations that lie outside that realm. This tutorial details how color is handled in digital video systems, from acquisition, through processing and recording, to display, in conventional 525-line and 625-line resolution, and in emerging high definition television (HDTV) systems.

The tutorial will explain the color separation mechanisms used in contemporary cameras, and discuss the ubiquitous CCD image sensor. Also discussed is the linear matrix processing that is used to improve the color performance of high-end cameras. Video signals are invariably subject to a nonlinear transfer function that mimics the lightness sensitivity of human vision. Though referred to by a pejorative term, "gamma correction," this nonlinear processing is quite essential to achieving good perceptual performance in a limited number of bits per component (say 8 or 10).

Benefits: Attendees of this tutorial will be able to:

• understand how the nonlinear video "luma" differs from luminance, and explain several flavors of color difference components that are in use in different applications Y'PbPr, Y'CbCr, Y'UV, and Y'IQ

• describe methods used for subsampling, the first step in video compression systems such as motion JPEG and MPEG

• understand the new luma coefficients of HDTV standards and outline the factors impacting the exchange of image data between HDTV and conventional digital video

• summarize how color is handled in displays beginning with classic CRT displays, and discuss the tradeoff between color gamut and display brightness

• describe how wide-gamut image data is accommodated in image coding systems such as PhotoCD and HDTV

• identify the challenges to color reproduction that are presented by emerging display technologies such as liquid crystal displays(LCDs), plasma display panels (PDPs), digital micromirror displays (DMDs), and other light valve technologies

Intended Audience: It is assumed that attendees are familiar with classical colorimetry, and will be comfortable with some integrals and dot products.

See also, Color in Desktop Computing: From Theory to Practice.

For registration details, see the Color Imaging Conference Tutorials page.

Charles Poynton - Courses & seminars
1998-07-17