HDTV Aspect Ratios

30 April 2007 No Comment

Yet another thing to consider when choosing an HDTV is what’s known as the Aspect Ratio, which is the ratio of the width of the image to its height. Because HDTV is wider than standard TV (its aspect ratio is 16:9, compared with standard TV’s 4:3), a film shot using standard definition won’t fill the whole screen on an HDTV. There are a number of different ways of resolving this, not all of them satisfactory, and which you choose is dependent upon your own preferences.

Note that the complexities involved with aspect ratio are inherent to all HDTVs.

Letterboxing and Pillarboxing

The most obvious way of displaying a 4:3 image on a 16:9 screen is simply to display it as is, without stretching the image in any way. Unfortunately, this gives rise ugly black bars appearing either above and below the image (letterboxing), or to the left and right (pillarboxing).

However, this is how the image has to look if it’s not been altered, as a 4:3 image simply will not fill up all the space available to it with a 16:9 screen. Given that you’ve spent all that cash on a shiny new widescreen HDTV, though, you’ll obviously want to fill out all the space that’s available to you, and here’s where the complexities begin.

Note that letterboxing and pillarboxing are only an issue with images that have been recorded for standard definition TV. HDTV broadcasts are filmed in a 16:9 format, and so will fill up the entire HDTV screen anyway. Once the major networks film everything in HDTV, letterboxing will become a thing of the past. In the meantime, however, you’re stuck with trying to make a 4:3 image fill a 16:9 screen.

Horizontal (or Full) Stretch

This mode stretches the 4:3 image so that it fits the 16:9 screen horizontally. You’ll fix pillarboxing, as the image is stretched to the full width of the screen, but will still get horizontal bars above and below the image. Of course, stretching an image in one direction only gives the effect of making everything and everyone look fat.

However, certain DVDs are recorded in “Enhanced for Widescreen” (or “anamorphic”) format, in which the horizontal stretching won’t make things look fat, as the film has already been filmed using the appropriate width for a 16:9 screen. Rather unhelpfully, though, you might still get horizontal bars at the top and bottom, as the height of the film may not be correct for a 16:9 screen (don’t ask why – this is HDTV, it’s designed to be this complicated!)

Note that you can choose to view anamorphic images without the horizontal bars, but with the downside that everything is stretched vertically. For the correct width on a widescreen HDTV (but with the horizontal bars), choose 4:3 aspect ratio on your DVD. For the vertically stretched approach, choose 16:9 on your DVD. If, however, you’e using a standard 4:3 TV, then choose 16:9 for the DVD’s aspect ratio (no-one said this was easy, remember!)

Panorama or TheaterWide Modes

One other option is to set your aspect ratio to Panorama or TheaterWide mode. This stretches the images at the extreme left and right of the screen, but leaves the central area intact, ensuring people are of normal proportions when they’re in the center of the action, but making them look like they’re eating an increasing number of pies the further to the edges they go.

Zoom or Pan and Scan

Another way of getting rid of the black bars is to use the TV or DVD’s zoom control (sometimes called Pan and Scan), in which the image is literally zoomed in until it fills the 16:9 space. The downside of this, of course, is that parts of the screen will disappear off the edge.

The image itself will also appear less clear, as you’re using digital zoom, which simply takes a pixel and copies its colour to several surrounding pixels. The result is the same as digital zoom on a camera – great if you squint, but don’t expect a pin-sharp picture any more (which, given that that’s why you bought such an expensive HDTV in the first place, is something of a disappointment!)

Sometimes, a however, an image will appear with both letterboxing and pillarboxing (i.e. black bars at the top and bottom and left and right sides of the image). If this is the case, your only option is either to watch the small-but-sharp image as is, or zoom the image until it fills the screen. Again, the image will appear less clear, but it will be bigger, won’t be stretched out of proportion, and you won’t lose any of the image either.

 
  1. 1). HDTV Formats and Resolutions
  2. 2). HDTV Connections – from HDMI to Composite Video
  3. 3). HDTV Sources – Hi-Def DVD players, Games Consoles, Cable and Internet
  4. 4). HDTV Aspect Ratios
  5. 5). HDTV Plasma TVs vs HDTV LCD TV – which is best?
  6. 6). HDTV Info Summary
 

Leave a comment