Understanding Widescreen, Letterboxed, and Pan & Scan
Why are There Black Bars on My TV? Understanding Aspect Ratios
A Long Time Ago, in a Galaxy Not So Far Away…
Someone introduced us to widescreen videos on VHS. These videos presented the full picture as you saw it in the theater, but did so on our 4:3 (non-widescreen) televisions. Later, DVD came along; followed by high definition widescreen televisions, and life got confusing (but better.) In order to understand all of these differing formats you'll need to understand something about each and the purposes for which they were designed.
Definitions and Terms
Aspect ratio: the ratio between the width and height of an image.
Standard aspect ratio for high definition television
Standard aspect ratio for standard definition television (NTSC/PAL) and Digital Television (DTV).
The presence of black bars at the top and bottom of the picture. Usually referring to playing widescreen format pictures on standard definition television. Also refers to the old practice of encoding black bars along with the image on VHS tapes and early DVDs as a poor means of producing a widescreen image.
Anamorphic or Widescreen
This is the typical standard for encoding widescreen content on a DVD such that it utilizes all available resolution in the encoding process. The DVD player then expands the image appropriately (if set correctly) for both 4:3 and 16:9 televisions.
Pan and Scan
Movies encoded into 4:3 ratio by intelligently panning and scanning horizontally across the widescreen film to keep the action in the middle of the screen. Though better than merely cropping the image, this still results in a loss of at least 30% of the original image.
Remember VHS & Laserdisc? It Kind of Started this Whole Craze.
When VHS came to market, people, for the first time, could watch theatrical movies in their homes. Some intelligent producers actually thought that some people would perhaps enjoy actually seeing the whole film. As a result, letterboxing was developed to mat the picture with black bars on the top and bottom, enabling the wide center area to show the aspect ratio of the original theatrical presentation. Prior to this everything was presented in Pan and Scan mode whereby the wide version of the film was intelligently cropped to where the action was - but still eliminating 30% or more of the picture.
Editor's Note On the Origin of Letterbox
Several CED titles were issued in letterbox format ("Amarcord", "The Long Goodbye", "Manhattan", "Monty Python and the Holy Grail" and RCA's "King of Hearts"). RCA called this their "innovative widescreen mastering technique," and on the back of the caddy provided an explanation for the black bands at the top and bottom of the television screen. CED was the first video format to feature letterboxing, with the release of "Amarcord" in January 1984. This was eight months prior to the release of "Manhattan" on LaserDisc, which is often mistakenly considered the first letterboxed release. - thanks to Jeff Lawson for this info
In 1984 the Voyager Company debuted its Criterion Collection line of special-edition video laserdiscs, with additional revolutionary features such as language options, original aspect ratio widescreen and letterboxed formats (rather than pan-and-scan), supplementary materials, commentaries by directors on audio tracks, interviews, making-of documentaries, photo galleries (stills, posters, artwork, storyboards, shooting scripts), state-of-the-art mastering, and other extras. Their contributions solidified the laserdisc as the choice of cinephiles for over 15 years. These features later became commonplace on releases of DVDs. - thanks to John Ambro for the quote from filmsite.org
In addition (and if anyone can show me proof of which format had the first letterbox I'll include it here) the laserdisc was created to give widescreen and standard definition formats a higher-quality source format for those getting into big screen TVs and the whole home theater craze. Laserdisc was the first optical disc format for home theater, though technically it was still a digitally encoded analogue NTSC signal. Once big screen TVs started becoming popular, the letterbox format exploded.
What letterboxing did was allow the entire width of the film to be shown. What it did not do was efficiently accomplish this task. By introducing black bars at the top and bottom, VHS effectively eliminated 1/3 of its precious 280 lines of resolution. Oh they were still there, but they were taken up by black bars. Now we had only about 160 or so lines of resolution on which to watch our movies. At the time, this was all that was possible. And honestly, it was a good solution given the consumer format limitations at the time.
How DVDs Changed the Way We Watch Movies
DVDs provided the same ability to watch widescreen presentations on our 4:3 standard definition televisions, but with one very important change. The DVD spec allowed the picture to be "pre-squished" into what we now call anamorphic (or sometimes dubbed "widescreen") video. Without processing, this condensed video would appear on a 4:3 television as if everyone were tall and skinny. DVD players, however, could take this content and stretch it back out to the correct aspect ratio and provide the black bars on top and bottom. In case you missed the critical difference between the way DVDs and VHS handle this - realize that the DVD is using up to its full potential of resolution to store the picture. It does not necessarily need to waste precious video real estate on black bars (we're generalizing for simplicity; there are actually many aspect ratios where a small amount of black bars must be encoded.)
Don't Some DVDs Actually Letterbox Films and Encode Black Bars?
Yes, but those DVDs are generally very old movies sold for $5 or less that are simply a quick transfer from some master in order to get the content to market expeditiously. When the DVD format first came out there were instances of confusion as DVD authoring was still new, however most current or remastered mainstream films are encoded correctly as anamorphic.
High Definition Televisions and Aspect Ratios - I Still See Black Bars!!!
Yes, HDTVs did not eliminate the need for black bars. What we hope, is that once people understand the reason for this, it won't bother them nearly as much. HDTV did for television what DVD did for home video - and it's now doing so at about the same amazing pace. Widescreen TVs, and high definition television programming is set at a 16:9 (or 1:1.78) aspect ratio. They match. What doesn't match are many films which are shot at a much wider aspect ratio, as well as standard definition and DTV programming which is still at 4:3.
What this means is that even though you now have a brand new high definition television, you will still experience black bars from time to time, or you'll need to scale your video to stretch to fit the TV. In either case, this isn't a bad thing, just part of being involved in a transition period and point of tremendous technological change.
Recommendations for Handling Formats Correctly on Your Television
Before making any recommendations, we'll need to know what kind of television you have and what you're watching. Here are some common scenarios and our suggested guidelines:
- HDTV with HDTV content: Congratulations, you'll be enjoying the full potential of your television with no black bars or distortion. Be sure your TV is set to its standard (non Zoom, non stretch) mode for the best possible picture.
- HDTV with standard definition, DTV content, or 4:3/pan-and-scan/full screen DVD: In order to watch content in its proper aspect ratio you'll see black bars on the left and right of the television screen (effectively rendering your new 16:9 television into a 4:3 television.) Another option is to use a stretch or smart stretch mode to fit the content to the full width of the television. Make sure your DVD player is set correctly in 16:9/widescreen mode.
- HDTV with widescreen/anamorphic DVD: Here you will see black bars on the top and bottom of the picture. This is simply because the original image is wider than the HDTV. To preserve the picture in its entirety, leave the television set to standard mode and be sure your DVD player is set correctly in 16:9/widescreen mode.
- Standard 4:3 TV with standard definition, DTV content, or 4:3/pan-and-scan/full screen DVD: You won't have any problems playing any of this content on your TV and it will show without any black bars. Make sure your DVD player is set correctly in 4:3/pan-and-scan mode.
- Standard 4:3 TV with widescreen/anamorphic DVD: Here you will see black bars on the top and bottom of the picture. This is simply because the original image is significantly wider than the TV. To preserve the picture in its entirety, leave the television set to standard mode and be sure your DVD player is set correctly in 16:9/widescreen mode.
So where does this leave us? Well, it hopefully explained a bit about aspect ratios and why black bars are going to be a part of your television viewing experience for some time. I also hope it illustrates that these black bars are not necessarily a bad thing as they preserve and display movie content in the manner it was original conceived.
There is some excellent video processing technology that was just shown off at the 2005 CES expo and it is slowly but surely working its way into newer televisions and DVD players. As a result, scaling options and general display scaling quality is getting better and better, making it possible to have more options for viewing content in formats that fill more of the screen without creating distracting image distortions or glaring video errors. We can't wait.
As always, enjoy the movies!