Have you ever wondered what it means when you hear 16x9, Fullscreen, Widescreen, or Pan and Scan? More importantly what does that mean to you as a consumer? I'm going to give you a few simple explanations with examples of aspect ratios.

These are the terms and ratios we are going to be covering: Widescreen, Fullscreen, Pan and Scan, Letterbox, 4x3, 16x9, 1.33:1, 1.78:1, 1.85:1, and 2.39:1. Now there are more ratios and those can be found over at the Aspect Ratio Wiki, but these are the most common ones.

Terms

Fullscreen - This term comes from when there were no 16x9 HDTV's all TV's were a 4x3 square image. Companies made the decision that people didn't like that when they watched a movie, it didn't fill up the entire screen, it had black bars on the top and bottom, so people wanted a "fullscreen" image. In order to accomplish this, each frame of the movie is looked at and decided up what portion of the original image is going to be cropped.

Widescreen - This is a semi loose term. It basically covers anything wider than full screen or a 4x3 ratio.

Pan and Scan - Unlike Fullscreen where a frame is completely cropped, pan and scan actually shows you the entire original frame, but it pans across the frame to fit within the full screen ratio. This always creates a blurred look, or artifacts showing when it is accomplished.

Letterbox - This is a way to keep the original ratio on a 4x3 television. It adds black bars on the top and bottom of the frame to fill the screen but keep the ratio.

Ratios

Ratios are simple numbers that let you know how the film was shot.
For example a 1.78:1 means that for every unit of 1.78 wide you need to go 1 high. So if we are using inches the ratio is 1.78 inches wide and 1 inch tall.
A more practical example would be a 50" HDTV which has a ratio of 1.78:1. This would mean that the viewing size is 43.57 inches wide by 24.50 inches high.

Below are examples of different ratios based on an original image* ratio of 2.39:1. You will see the ratio within the 2.39:1 ratio.

4x3(1.33:1) -This is the standard Full Screen square TV size. Notice how much image is lost to cropping.
Example of 1.33:1 ratio:

16x9(1.787:1) - This is the standard for HDTV programing which relys on a resolution of 1920x1080 or 1.78:1. Film can still be cropped to fit on a 16x9 HDTV.
Example of 1.78:1 ratio:

1.85:1 - This is a standard ratio for a lot of movies you see in the movie theatre. Its only slightly wider than 16x9.
Example of 1.85:1 ratio:

2.39:1 - This ratio is also used in a lot of movies, usually the bigger budget movies as the film stock costs more.
Example of 2.39:1 ratio:

There are various other ratios that movies are filmed. The highest ratio that has ever been filmed was 4:1 called Polyvision. To accomplish this three 35 mm 1.33 images projected side by side. It was used only on Abel Gance's Napoléon (1927). (ref Aspect ratio (image))
Example of 4:1 ratio:

*The image provided was shot by myself in the Philippines on the island of Davao, Island Garden City of Samal.