The Many Shapes of a
TV Screen
I always thought it was just my imagination. It seemed that
every time I played a letterboxed video tape or disc, it took up a different amount of the
TV screen. And sometimes even the images in pan-and-scan tapes looked somehow different
than I remembered them in the theater. Surely Hollywood had a standard for widescreen
films, I thought, and surely the pan-and-scan process was simply a matter of deciding
where to place the 4:3 "window" in the wider image.
Wrong.
Some years ago I was disabused of these naive notions by a
fascinating -- if appallingly written -- American magazine called Widescreen Review.
The publication itself is a treasure trove of behind-the-scenes information about the
technical side not only of movie-making but also of the interaction between the films and
the electronic media we employ to watch them. For videophiles interested in how a
"colorizer" actually transfers a movie to tape or disc, for instance, or who
want in-depth technical disc reviews, this is the place to find them.
What caught my eye in one early issue was a discussion of
the various aspect ratios used in movie-making. It's a hot topic today as digital
television is altering a standard that goes back to Thomas Edison and the first moving
pictures, and old visual material has somehow to be fit into the new shape.
Aspect ratio is the relationship of an image's width to its
height: television and early movies were standardized with a 4:3 ratio (which movie folks
are inclined to express as 1.33:1). The high-definition version of digital TV has a ratio
of 16:9 (or 1.78:1), and an increasing number of NTSC sets, along with some HDTV-ready
televisions, have been marketed with that shape as an interim step. True high-def sets all
have 16:9 screens
But what sort of compatibility is there in any of this? Not
much, as it turns out. For one thing, "widescreen" has a number of different
meanings. In recent years, the motion picture academy has standardized -- nominally -- on
a ratio of 1.85:1, which would be fine if they stuck to the standard. But a film released
in 70mm (on double-width stock) has an aspect ratio of 2.05:1, while an anamorphic
Panavision print -- where the image is squeezed horizontally to fit on regular 35mm film
and then stretched by the projector -- is 2.35:1. The Europeans have a separate standard
completely: 1.66:1.
The 1.85:1 Academy Standard is usually employed in the
actual making of a film, however it may ultimately be delivered to the theaters. In most
cases, widescreen release prints are basically blowups of images shot on conventional 35mm
film. Sometimes the camera itself contains an opaque mask (called a "hard
matte") that blocks the top and bottom of the image, leaving a picture in the center
of the frame with the desired aspect ratio -- in effect the picture is letterboxed from
the start.
Alternatively, in the "soft matte" process, the
full frame is exposed, with the eventual crop indicated by lines in the viewfinder. The
eventual shape of the image is determined by masking in the duplication process or even by
the projector in the theaters themselves. One advantage of soft matting is that the same
original can be used to produce release prints in several different formats.
Not only that, but pan-and-scan video versions frequently
include some of the material cropped in the theaters. If a two-shot puts the actors on the
opposite sides of the screen in the wide version, it might be necessary to cut back and
forth continually between them in the pan-and-scan video -- an annoying effect. But by
including material above and below the theatrical shot, both actors can be on screen at
once, but now in a more distant framing. That's convenient but does some violence to the
director's intention.
To avoid that, a widescreen format has been in the cards
for high-definition television from the day it was first proposed, almost two decades ago.
And in fact, the 1.78:1 HDTV standard is probably the best compromise possible between the
various formats. Both the American 1.85:1 and the European 1.66:1 standards will reproduce
almost perfectly on the new sets, with only negligible bits of the picture missing.
Unfortunately, vast quantities of material created by
Hollywood over the past half century will still leave those irritating black bars on the
screen, even though they may be smaller than on conventional sets. And almost all pre-HDTV
4:3 television material will still either leave vertical black bars down the sides of the
screen, or will fill the screen but lose a lot of picture at the top and bottom.
Movie theaters that have curtains get around this problem
by adjusting them so they only open wide enough to expose the part of the screen that will
be filled. That requires a screen that can display a Panavision image full height, and
it's unlikely that anyone is going to produce a home display capable of the full 2.35:1,
so although 16:9 is a great improvement over older screens, we're still going to be stuck
with blank screen areas for some time to come.
...Ian G. Masters
ian@mastersonaudio.com
|
