Television Screen Dimensions and Resolution
Widescreen vs Pan & Scan
Standard vs Anamorphic

Aspect Ratios

 - sometimes wrongly referred to as "Resolution"

Aspect Ratio can mean:

The video's ratio may or may not be equal to your screen ratio.  If you see black bars, then of course, the video ratio is not the same as your screen ratio.

Aspect Ratio = Width Height = Width/Height = Width:Height

The 3 common ways that aspect ratio is written

1)  using whole numbers on either side of the colon.  For example, 4:3 (some even display it as a fraction, as in  4/3 )

2)  converting it so that the Height is "1" and the width is given as a decimal number.  The advantage to this is that it tells you instantly how large the width is comparatively to the height. 

3)  as a single decimal number.  This is a simple way of displaying method 2.  Once the aspect ratio is converted to Height = 1, then the height is sometimes left out, and assumed as = 1

Example:

1)  4:3 is the standard NTSC TV screen aspect ratio
2)  that can be converted to a height = 1 by dividing both the numerator and denominator by 3, or 1:33.1
3)  using method 2 to convert the height to 1, we can then leave out the height entirely.  Since it is 1, and this is so commonly done, whenever a ratio is given as a single decimal number, everyone knows that the height is = 1.  So our example can be written in 3 ways:

4:3  =  1.33:1  =  1.33

Why Resolution  Aspect Ratio  -  Resolution is a ratio but it is measured by dots, or pixels.  The resolution may have a different ratio than the displayed picture, since many viewing formats include squeezing of pixels, skipping of pixels, doubling pixels, and even using non-round pixels (oval pixels).  This is why it is a misnomer to call resolution, the aspect ratio !!

 

Widescreen  vs  Pan & Scan

Movies are filmed is a very wide format . . . much wider than traditional TV screens.  Enter Pan and Scan . . . . and then later . . . Widescreen

Widescreen vs Pan&Scan  .  .  .  as always, it has become this controversy between purists of both camps.  As always, each format has advantages and disadvantages ad the most honest approach is top simply be aware of both formats and select which one you prefer without going extreme about it

Here is an example of a flash animation from a Widescreen advocacy site . . . http://www.widescreen.org .

a Flash Animation from the Widescreen Advocacy Page
about the "horrors" of Pan & Scan, and the greatness of Widescreen

They forgot to mention that their favorite method shrinks the movie way down !!
Which is why, personally . . . I like Pan and Scan !!!

Now that TV's are moving to HDTV format, the days of the 4:3 (Width:Height) screen ratios are numbered.  But that conversion, originally planned by law to occur in 2008, will actually take quite a while.  So for now the DVD's you rent come in a number of screen resolutions and dimensions, and your DVD player and/or TV must use a method to change it to fit your screen . 

Standard Dimensions

The screen ratio is defined as Width:Height.  NTSC TV's are at 4:3 (1.33 to 1) and HDTV's are at 16:9 (1.78 to 1)

TV (green box), and two common film ratios (blue and red boxes)  -  HDTV not shown

TV = 1.33:1  (same as 4:3)
Film = 2.35:1 (CinemaScope or PanaVision)  and  1.85:1
(HDTV = 1.78:1 which is the same as 16:9)

Pan and Scan - also called "Full Screen" - the typical way that a film is converted to TV.  Information is encoded into the DVD tracks to tell the player where to place a virtual 4:3 window, and where to move it, should the action move off center.  This 4:3 window is - by default - placed in the center of the wide movie, and whatever fill that window, is what fills your screen  -  the rest is chopped off.  If the action moves off center, the pan and scan track tell the player to also move the window off center. 

Now . . . as the viewer, you don't see the movement of this window because your TV is stationary.  There are many ways of creating the pan and scan tracking data.  That is done by the movie houses and finishing shops.  If done right, it is a tedious process, where they try to keep the window in the center as much as possible, and they try to move off center as little as possible, and when they do move . . . as smoothly as possible.

Widescreen - also called "Letterbox" - you've all seen this  .  .  .  the hated black bars.  Well some purists are crazy about preserving the film and they love the black bars !!!  This allows you to see the entire, original movie content, but at a much smaller size.  Letterboxing simply shrinks the original film way down in size, and keeps the same dimensions.  Since it is wider than your 4:3 TV screen, the end result is a mat that the picture fits into.  There are black bars on the top and bottom, enabling the wide center area to show the aspect ratio of the original theatrical presentation.

Black Bars even with HDTV

If you buy an HDTV, most modern DVD movies will fill the screen perfectly, at 16:9 .  But some movies, called widescreen/anamorphic - are shot at an even wider ratio, and those will cause black bars on an HDTV.  You may have noticed the effect on your standard TV, where most black bars are at a certain thickness, but sometimes you insert a DVD and the black bars are huge, while the movie seems really, really short and wide.

Anamorphic DVD's

(16:9 Enhanced)  -  (from http://www.widescreen.org/dvd_anamorphic.shtml )

In order to allow widescreen TV owners to see a movie on their widescreen TV without sacrificing image clarity, anamorphic (also called "16:9 Enhanced") DVDs were created.

First, let's define the term "anamorphic".

There are essentially two definitions. When it comes to movie theatres, anamorphic movies are compressed horizontally. This allows a wide image (up to 2.40:1) to be stored on a standard (1.33:1) frame; however, when you view a raw anamorphic image that has not been expanded horizontally, people look thin and anorexic and circles look like tall ovals. Such a movie is then projected onto the movie screen with a special lens that expands the movie out to its original width on the screen. Below is an example.

 
Example of theatrical anamorphic compression

When it comes to DVDs, anamorphic DVDs are specially encoded to include more visual information than standard DVDs. When an anamorphic DVD is played on a standard 4:3 TV, every fourth line of this extra resolution is ignored. (Keep in mind that your DVD player needs to be set for a 4:3 TV.) You still get a superb picture and you probably would not be able to tell the difference between anamorphic and non-anamorphic DVDs.

When an anamorphic DVD is played on a regular TV and your DVD player is set for a 16:9 TV, that extra information is restored; however, because that image is meant to be stretched by a 16:9 TV, the result will be that people look thin and anorexic and circles look like tall ovals. Now you can see where these DVDs get the term "anamorphic DVDs".

When an anamorphic DVD is played on a widescreen TV and your DVD player is set for 16:9 TVs, that extra information is restored giving you a picture that properly fits the width of the screen but without having to increase the size of the pixels. This gives you a much sharper image than non-anamorphic DVDs.

Both of these share the term "anamorphic" because if you look at the raw image (before horizontal expansion), people will look anorexic, circles will look like tall ovals, and squares will look like tall rectangles. With respect to DVDs, you will see this if you have a 4:3 TV but your DVD player is set to 16:9 and you attempt to play an anamorphic DVD.

The screen shots below demonstrate this.

 
Non-anamorphic image on 4:3 TV
Non-anamorphic display on a 4:3 TV
 
Anamorphic image on 4:3 TV
Anamorphic display on a 4:3 TV
(has an annoying squished look)

Viewing an anamorphic ("16:9 Enhanced") DVD on a widescreen TV results in a clearer image because the image only needs to be expanded horizontally. Because DVDs already have an exceptionally high resolution horizontally, you can see very little difference in quality due to the horizontal expansion or stretching.

When viewing a non-anamorphic DVD on a widescreen TV, the image needs to be expanded horizontally and vertically. Because TVs have a smaller number of vertical lines than they do horizontal lines, zooming in on the image will produce a very grainy result compared to the horizontal-only stretching of anamorphic DVDs.