9.2.1 Introduction

In the years after the ATSC standard for digital television was approved for implementation, the SMPTE coordinated considerable efforts to define a family of scanning formats and interfaces for the multiple picture rates accommodated by DTV. The results of this work some still ongoing as this book went to press are outlined in the following sections.

9.2.2 1920 1080 Scanning Standard

SMPTE 274M defines a family of raster-scanning systems for the representation of images sampled temporally at a constant frame rate and within the following parameters [1]:

• An image format of 1920 1080 samples (pixels) inside a total raster of 1125 lines

• An aspect ratio of 16:9

The standard specifies the following elements:

• R ? G ? B ? color encoding

• R ? G ? B ? analog and digital interfaces

• Y ? color encoding and analog interface

• Y ? color encoding and digital interface

An auxiliary component A may optionally accompany Y ? , denoted Y ? A. It should be noted that, in this standard, references to signals represented by a single letter, that is, R ? G ? B ?, are equivalent to the nomenclature in earlier documents of the form , which, in turn, refer to signals to which specified transfer characteristics have been applied. Such signals commonly are described as having been gamma-corrected.

The system parameters for SMPTE 274M are listed in Table 9.2.1a. Analog interface timing details are given...