Nikon D300 User Manual page 603

HDTV's (High-Definition Television) broadcast resolutions.
In the good old days of SDTV (Standard-Definition
Television) that we all grew up watching, there was even less
resolution. Would you believe that the old TV you have
stored in the garage displays only 345,600 pixels, or 0.3
megapixels?
I've been talking about the number of megapixels, but that's
not normally how HD devices are rated. Instead of the
number of pixels, most HD information talks about the
number of "lines" of resolution. There are several HD
standards for lines of resolution. The standards that are
usually the most used are 720p, 1080i, and 1080p. The "p"
and "i" after the numbers refer to "progressive" and
"interlaced". We'll talk about what that means in the next
section.
The D300S's best D-Movie mode captures in 720p, which is
a broadcast-quality HDTV standard. The "720" simply means
that your camera captures and displays HD images with 720
lines of vertical resolution. Each of those lines can be 1,280
pixels long, which allows the D300S to match the 16:9 aspect
ratio expected in HDTV. An older SDTV usually has an
aspect ratio of 4:3, which is taller and narrower than the
HDTV 16:9 aspect ratio.
Progressive vs. Interlaced
What's the difference between progressive and interlaced?
Technically speaking, progressive video output displays the
video frame starting with the top line and then draws the other
lines until the entire frame is shown. The D300S displays 720
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