16x9 Aspect Ratio Defined
The term 16x9, also expressed as 1.78:1, means the TV screen is 16 units wide horizontally, and 9 units high vertically. No matter what the diagonal screen size is in inches or centimeters, the ratio of horizontal width to vertical height (aspect ratio) is constant for HDTVs and 4K Ultra HD TVs.
Aspect Ratio and What You See on Your TV Screen
The reason that you see black bars on some movie content is that many films use wider aspect ratios than 16x9. For example, since the DTV transition, original HDTV programming has the 16x9 (1.78) aspect ratio, which fits the screen dimensions of today’s LCD (LED/LCD), Plasma, and OLED HDTVs and 4K Ultra HD TVs. However, since the mid-1950s, many theatrically-produced films have featured wider aspect ratios, including 1.85 and 2.35. You will see black bars on the top and bottom of a TV screen when you watch these films on an HDTV or 4K Ultra HD TV (if presented in their original theatrical aspect ratio). Aspect Ratios can vary from program to program. If you’re watching a DVD, Blu-ray, or Ultra HD Blu-ray Disc, the aspect ratio listed on the package labeling will determine how it looks on your TV (many DVD packages may also state “Enhanced for 16x9 TVs”).
If an HDTV program or film is 1.78:1, then it will fill the entire screen correctly.If the aspect ratio of a film is 1.85:1, then you will notice small black bars on the top and bottom of the screen.If the aspect ratio of a film is 2.35:1 or 2.40:1, which is typical for big blockbuster and epic movies, you will see large black bars on the top and bottom of the image.
On the other hand, if you have a Blu-ray Disc or DVD of an older classic movie and the aspect ratio is listed as 1.33:1 or “Academy Ratio,” or you are watching a rerun of a TV program made before HDTV was typical, then you’ll see black bars on the left and right side of the image on a 16x9 aspect ratio screen, instead of the top and bottom (a “pillar box” image). Movies made before the frequent use of widescreen aspect ratios or TV shows made before HDTV was in use (those old analog TVs had an aspect ratio of 4x3, which is more “squarish” looking) result in pillar box images. On HD and Ultra HD TVs, as well as most video projectors, you can stretch a 4x3 image to fill the space. However, doing so distorts the proportions of that image, resulting in objects appearing wider horizontally, which is especially noticeable on the sides of the picture.
Black Bars vs. Filling the Screen
When viewing TV shows and movies, the primary concern is whether you see everything in the picture, especially if you see the image on a projection screen, which is larger. Real HDTV programs fill the screen. Many movies have display black bars on the top and bottom of the screen, and most films made before the mid-1950s and pre-HDTV shows present with black bars on the left and right side of the image. The TV screen is providing a surface upon which you view images. Depending on the format, the entire picture might or might not fill the whole screen. However, the screen surface on a 16x9 television can accommodate more variations in the aspect ratio realistically than older, 4x3 analog televisions.
