I Never Thought about That
Written June 23, 2007
Few television viewers are aware of it, but we broadcasters have to consider compatibility. Our pictures must display properly on old black-and-white TV sets as well as the latest wide-screen plasmas. Here's a peek at those issues.
When I started in the business, an improvement was under way: most TV programs had recently been upgraded from black and white to color, although many people were still watching on black and white sets.
My textbook, the Television Production Handbook by Herbert Zettl (1969 edition), included a few pages about color production. We were cautioned that even though a picture looks good on a color TV, it won't necessarily look good in monochrome.
This first example from Zettl has enough contrast to work either way.
This second example does not. Many of the bright colors translate to roughly equal shades of gray.
Nowadays almost no one watches television in black and white. We no longer pay much attention to how our pictures look in monochrome, although it's still unwise to put gray letters on a bright red background.
However, we do have a new compatibility problem to worry about. Another improvement is under way: most TV programs have now been upgraded from "standard definition" to widescreen high definition, although most people are still watching on their old TV sets.
HD produces nice wide pictures like this frame from a commercial. On a 36-inch screen (measured diagonally), the image will be about 32 inches wide and 18 inches tall. That's an aspect ratio of 32/18 or 1.78.
But
many viewers have old-fashioned 20-inch screens, measuring 16 inches
wide and 12 inches tall. That's an aspect ratio of 16/12 or
1.33. For those viewers, we have to somehow fit our oblong
32-by-18 peg into their squarish 16-by-12 hole.
|
Mathematical note: in this example, we're converting a 720-line high-def picture to a 480-line standard-def picture, each displayed at a pixel pitch of 40 lines per inch. |
|
Suppose the real golfer is six feet tall (72 inches) and 16 inches wide. His image in the big picture is 9 inches by 2 inches, or 1/8 life size. But in the small picture his image is 6 inches by 1 inch. We assume he's still six feet tall, so the image must be 1/12 life size and he must be only 12 inches wide (and 12 inches thick). His weight is proportional to the volume of his body, which is proportional to height times width times thickness. According to the first picture, that's 72 x 16 x 16 = 18,432. According to the second, it's 72 x 12 x 12 = 10,368. The ratio of apparent weights is 1.78. (Where have we heard that ratio before?) And 200 pounds divided by 1.78 is 112 pounds. |
One
possibility is to reduce the width by half (from 32 down to
16) while reducing the height by only a third (from 18 down to
12). This fills the hole exactly, but people become rather
skinny. A 200-pound man appears to have shriveled to 112 pounds.
|
From working in control rooms, I've actually become accustomed to pictures distorted in this manner. I might not object to the skinniness. But most viewers would. You'd object, wouldn't you, Mona? |
|
Two other methods are more practical because they don't distort shapes. Interestingly, NBC's late-night talk shows disagree on which is best.
The first method is used for Late Night with Conan O'Brien and for most televised movies. The 32-by-18 picture is shrunk by half in both dimensions, to 16-by-9, so it can be displayed on an old-fashioned 16-by-12 screen. But the resulting picture, only 9 inches high, doesn't fill the entire 12-inch height of the screen; black bars remain at the top and bottom. The effect is like peering out at the world through one of those mail slots on a front door, or from the interior of a curbside mailbox, so it's called "letterboxing." The cinematic director's original framing is preserved and none of the picture is lost, but fine details such as text are now rather small.
The other possibility is called "center cut." We first lop off the "wings" on the left and right sides of the 32-by-18 picture. That leaves only the middle 24-by-18 portion, which then needs to be reduced by only a third (not by half) to fill the old-fashioned set's 16-by-12 screen.
This method is used for the Tonight Show with Jay Leno and for most sports. Central details like tiny football players are 33% bigger than they would be with letterboxing. But a quarter of the scene is missing: we no longer see the red flag on the right, nor the second golf bag on the left.
One consequence: on "center cut" sports productions, our camera operators must include more of the scene than necessary. They know that although HD viewers will be able see these wings (outside the yellow lines in the example below), most viewers won't. Therefore, they can't use the marginal areas to shoot anything important, such as the punter in a punt formation. And I mustn't put any of my statistics out there, either.
Another problem arises when we must insert old-fashioned footage into our HD show. If we do nothing, the old footage will show up with black bars in the wing areas. That shouldn't be a big deal. Most viewers will never see these bars. Our HD viewers will see them, but they're accustomed to black bars during some commercials, local news updates, and the like.
Nevertheless, in HD news and sports it's become customary to fill those wings with graphics, blurry backgrounds, or anything to give our widescreen viewers the full widescreen experience. Viewers with old TV sets, of course, will never see this filler.
It's an annoyance to have to "wing" the standard-def footage, but we must consider what will work best on all the different kinds of TV sets out there.
UPDATE, SEPTEMBER 16, 2007
More sophisticated solutions are being developed for the problem of the wings, in particular by ESPN.
In some HD studio shows, when a reporter checks in from another city, a standard-definition camera is shooting him in front of a static backdrop. Wings have to be added, but in this case, the wings are made to look like pieces of the main studio's set — literal "wings" in the theatrical sense — so they don't seem unnatural at all.
And some editions of SportsCenter have now added actual useful information to the wing on the right.
The right wing is headed "SC Rundown" and lists the upcoming stories. Soccer is playing now, to be followed by Angler of the Year, Top 10 Plays, What to Watch, then (after the top of the hour) Top Stories, Arkansas/Alabama, Saban, Roll Tide, and Louisville/Kentucky.
This column helps keep viewers tuned in. It says, "Even if you don't like soccer, stay with us. We'll have college football highlights for you soon." On the other hand, it may cause other viewers to change the channel when they learn there's no baseball coverage in the near future.
Even when SportsCenter shows high-def footage and doesn't need any wings, this rundown remains on the screen. It does hide an eighth of the picture, but remember that cameramen never include anything essential in that right wing area anyway.
When I first saw this right wing with info, I thought it was a bonus for HD viewers only. After all, viewers with old-fashioned sets don't see either wing because they get a center cut, correct? But no, there's now a more sophisticated solution, a non-centered letterbox that includes only the wing on the right.
Standard-def viewers see essentially the area in the yellow box above, including their own little bonus: they can see the lower edge of the footage, the part that HD viewers can't see because it's obscured by the strip of scores.
The art of television continues to evolve.
UPDATE, OCTOBER 6, 2009
Standard-def viewers of at least one cable channel are now seeing a letterboxed picture all the time. The details are here.
|
|
|
