Table 42.2 1080i and 1080p line assignment

start of line 561. In the second field, that EAV marks the start of line 1124; line 1 of the next frame starts on the second following EAV.

Analog sync

At an analog interface, each line commences with a trilevel sync pulse. The zero-crossing of trilevel sync defines the line sync datum 0H, to which horizontal events are referenced. Digital samples and analog timing are related such that the first (zeroth) sample of

Figure 42.1 1080i30 analog line details. Time intervals are shown as intervals of a reference clock at 74.25 MHz, with reference clock zero defined at 0H. To obtain sample numbers relative to the zeroth sample of active video, add SAL +88 (modulo STL) to these counts.

Vertical interval video lines do not convey picture information. They may convey ancillary or other signals either related or unrelated to the picture.

Analog signal timing is defined by the digital standard; the digital sampling frequency defines reference time intervals used to define analog timing.

Figure 42.2 shows details of the vertical sync structure; this waveform diagram is the analog of Table 42.2, on page 475.

Picture center, aspect ratio, and blanking

The center of the picture is located midway between the central two of the 1920 active samples (between samples 959 and 960), and midway between the central two 1080 picture lines (between lines 581 and 582 in a progressive system, and between lines 290 and 853 in an interlaced system).

The aspect ratio is defined to be 16:9 with respect to the production aperture of 1920× 1080.

In Transition samples, on page 378, I mentioned that it is necessary to avoid, at the start of a line, an instantaneous transition from blanking to picture information. A clean aperture pixel array 1888 samples wide and 1062 lines high, centered on the production aperture, should remain subjectively uncontaminated by edge transients.

R’G’B’ EOCF and primaries

Picture information is referenced to linear-light primary red, green, and blue (RGB) tristimulus values, represented in abstract terms in the range 0 (reference black) to +1 (reference white).

Three nonlinear primary components R’, G’, and B’ are computed such that the intended image appearance is obtained on the reference display in the reference viewing conditions; see Reference display and viewing conditions, on page 427.

In the default power-up state of a camera, the nonlinear primary components are computed according to the opto-electronic conversion function of BT.709 OECF, described on page 320; this process is loosely called gamma correction.

The colorimetric properties of the display primaries are supposed to conform to BT.709 primaries described

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