Understand Aspect Ratios

The first thing many people notice about an HDTV is its width. Whereas a SDTV is nearly square, an HDTV is distinctly rectangular. This is because HDTV format is designed to display images in widescreen, with an aspect ratio of 16:9. SDTV format has an aspect ratio of 4:3.

But what does this really mean? When watching a widescreen movie in high-definition, letterboxes disappear and images are displayed in full. However, HDTV aspect ratios can pose a problem when confronted with television programs or other materials captured in the old 4:3 format. Most HDTVs offer display options that deal with this issue, either by scaling or framing the image. If your HDTV’s solutions don’t work for you, there are intuitive ways to fix the problem—primarily, by using zoom control. As more content becomes exclusively HD, this will be less of a concern. However, if you need the most perfect image scaling right away, look into high-end HDTV scaling devices from manufacturers like Key Digital and DVDO.

DID YOU KNOW? The 4:3 aspect ratio used in SDTV programming was actually copied from film. Widescreen aspect ratios were not common in the cinema until the 1950s, when theater attendance plummeted and TV viewership increased. Movies were shown in widescreen in an attempt to differentiate the cinematic experience from the home-viewing one.