DigitalVideoAndHDTVAlgorithmsAndInterfaces.pdf

720p60
1280 × 720
1080p30,
1080i30
1920 × 1080
In Numerology of HDTV scanning,
on page 377, I explain the origin
of the numbers in Figure 13.2.
750
1125
1650
2200
1080
720
1280
74.25 MHz 16:9
1920
74.25 MHz 16:9
Figure 13.2 HDTV rasters at 30 and 60 frames per second are standardized in two formats,
1280×720 (1 Mpx, always progressive), and 1920×1080 (2 Mpx, interlaced or progressive). The
latter is often denoted 1080i, but the standards accommodate progressive scan. These sketches are
scaled to match Figures 11.1, 11.2, and 11.6; pixels in all of these sketches have identical area.
HDTV scanning
A great debate took place in the 1980s and 1990s
concerning whether HDTV should have interlaced or
progressive scanning. At given flicker and data rates,
interlace offers some increase in static spatial resolution,
as suggested by Figure 6.8 on page 59. Broadcasters
have historically accepted the motion artifacts
and spatial aliasing that accompany interlace, in order
to gain some static spatial resolution. In the HDTV
debate, the computer industry and the creative film
community were set against interlace. Eventually, both
interlaced and progressive scanning were standardized;
to be commercially viable, a receiver must decode both
formats.
Figure 13.2 above sketches the rasters of the 1 Mpx
progressive system (1280×720, 720p60) and the 2 Mpx
interlaced system (1920×1080, 1080i30) that were
agreed upon. The 1920×1080 system is easily adapted
to 24 and 30 Hz progressive scan (1080i24, 1080i30).
CHAPTER 13 INTRODUCTION TO HDTV 113