Monday, March 5, 2007

The Bumbling Revolution - Part 2:
It's All Screwed Up!

I have been asked by numerous people, numerous times, to explain HDTV. Or said in a better way, “Which flat panel TV should I buy?”

720x480, 640x480, 1920x1080... what is the significance behind these and other aspect ratios we sometimes love to hate? In this TechnoBabble segment of my blog, I'll try to present a straightforward introduction to the significance of video aspect ratios, and how video differs when presented on old style and new style televisions. Learning the differences between formats will give you a better understanding of exactly how video is displayed.

When you look at your old CRT television it is slightly wider than it is taller. This ratio is described as 4:3. Meaning it is 4 units wide by 3 high. The newer flat panels (and even some CRTs) came out in the wide screen format. This aspect ratio is described as 16:9. This is the standard for most flat panel screen, whether they be LCD or Plasma. The 16:9 ratio is closer to the theater experience, that allows you to see all of the picture.

Yes, many of you have looked on a DVD box and read "Anamorphic Widescreen 16:9 - 2.35:1" and thought "what the Fu*k!" Nevertheless, most of you will be familiar with the idea of ratios even if you think you don't. Imagine, for example, you are mixing a cocktail drink. It is four parts vodka to three parts of soda. That would be a ratio of 4:3. It doesn't matter if you used four gallons of vodka to every three gallons of soda, or four egg cups of vodka to every three egg cups of soda, it would still be a ratio of 4:3!

Aspect ratios work exactly the same way. Interestingly enough, your "old-style" TV screen is probably an aspect ratio of 4:3. That is, three parts down by four parts across. We measure the height and the width. For example, in the image below we have a ratio of 1.33:1 (or 1.33 to 1).

A second very often used aspect ratio is 16:9. That is, sixteen parts to every nine parts. This is basically what you will get from a widescreen TV.

Because they still represent the overwhelming majority of TVs in the marketplace, most television programming is already properly formatted for standard 4:3 TV's. But many movies as well as a small but steadily increasing number of TV shows (for example, David Letterman, American Idol, All of the CSI's) are broadcast in wide-screen format. Seen on your "old-style" 4:3 TV this letterboxing format--named because it duplicates the effect of staring through a mail slot--leaves black bars at the top and bottom of the screen.

Looking at your "old-style" 4x3 TV above, the letterbox bars are visible at the top and bottom--but you can see how the director intended the shot to look.

Standard TVs are pretty straightforward, but aspect-ratio issues can get a bit confusing once you upgrade to a set with a 16:9 screen (most HDTVs, for instance). Let's take a look at the common aspect-ratio problems in the wide-screen HDTV format.

The main problem with 4:3 sets is getting the rectangular shape" of wide-screen programming to fit the squarish "hole" of a standard TV. 16:9 TVs have the opposite problem: decades' worth of TV programming has been produced to fit the squared-off 4:3 aspect ratio, not the luxuriously wide space of a 16:9 display. There are several solutions, but you'll need to decide which sacrifices you're willing to make: deforming the picture, losing a portion of the horizontal image, sacrificing the resolution, or a combination of the three.

Before we take a look at the most common aspect-ratio problems that afflict wide-screen TVs, it's important to ensure that devices connected to wide-screen TVs - which include the overwhelming majority of HDTVs - should be set to 16:9.

You may ask yourself, "How do I get rid of those vertical black bars?" There are black (or gray) bars on the left and right sides of the screen when watching standard TV content on any HDTV set, for instance. This problem has three possible solutions. There's no right answer--just choose the one that's most visually pleasing to you.

Option one is you could use the zoom control on the TVto blow up the image, eliminating (or at least minimizing) the black bars. The image will fill the screen but you'll miss any action at the extreme top and bottom of the screen, which will be cut off--bad news if you're looking at the stock ticker, news crawl, or subtitles. Furthermore, the picture will appear softer because it's being electronically blown up, just like the muddy images one gets when using the digital zoom function on a digital camera.

Option 2 would be to set the TV's aspect-ratio control to Stretch or Full.The image will stretch to fill the screen. The black bars are gone, but to fit the square 4:3 image to the wider screen, the picture has been stretched horizontally, making everyone appear squat and bloated.

Lastly, you could set the aspect-ratio control to a nonlinear stretch mode such as Panorama or TheaterWide. The image will stretch to fill the screen, but only the extreme left and right will be distorted; anything toward the center of the screen will be displayed close to its proper proportions. It's a happy medium between native 4:3 and stretch, but this mode is implemented in some TVs better than in others. In some cases, panorama mode can be more distracting than pleasing.

Once you get used to viewing TV shows in their full wide-screen glory, we bet you won't be able to go back to the cramped confines of a cropped 4x3 version. The beauty of aspect-ratio control: it puts that choice in the hands of the viewer, not of a Hollywood director or network executive. For maximum flexibility, make sure it's at the top of the list the next time you're shopping for a TV or home-video peripheral.

Stay tuned, the next TechnoBabble Blog will get better!