Chapter 28, Problem 95PP

Resolving Lines on an HDTV

The American Television Systems Committee (ATSC) sets the standards for high-definition television (HDTV). One of the approved HDTV formats is 1080p, which means 1080 horizontal lies scanned progressively (p)—that is, one line after another in sequence from top to bottom. Another standard is 1080, which stands for 1080 lines interfaced (i). In this system it takes two scans of the screen to show a complete picture the first scan shows the “even” horizontal lines, the second scan shows the “odd” horizontal lines. Interlacing was the norm for television displays until the 1970s, and is still used in most standard-definition TVs today. Progressive scanning became more popular with the advent of computer monitors, and is used today in LCD, DIP, and plasma HDTVs.

In addicting, the ATSC sets the standard for the shape of displays. For example it defines a “wide screen” to be one with a 16:9 ratio; that is, the width of the display is greater than the height by the factor 16/9. The ratio is just a little larger than the golden ratio, $\varphi =\left(1+\sqrt{5}\right)/2=\mathrm{1.618......},$ which is generally believed to be especially pleasing to the eye. Whatever the shape or definition of a TV, the ATSC specifies that it project 30 frames per second on a progressive display, or 60 fields per second on an interlace display, where each ted is half the horizontal lines

For the following problems assume that 1080 horizontal lines are displayed on a television with a screen that is 15 7 inches high (32-inch diagonal), and that the light coming from the screen has a wavelength of 645 nm Also, assume that the pupil of your eye has a diameter of 5.50 mm. and that the index of refraction 01 the interior of the eye is 1.36.

• According to the Rayleigh criterion, what is the closest you can be to the TV screen before resolving the individual Horizontal Ines? (In practice you can to ccosOerably closer than this distance before resolving the lines.)

1. A.    3.51 ft
2. B.     4.53 ft
3. C.     11.5 ft
4. D.    14.0 ft