|
Introduction |
|
The image aspect ratio is its displayed
width divided by its height (usually expressed as 'x:y').
For instance, the aspect ratio of a traditional
television screen is 4:3, or 1.33:1. High definition
television uses an aspect of 16:9, or about 1.78:1.
Aspect ratios of 2.39:1 or 1.85:1 are normally used
for movies, while the aspect ratio of a full 35 mm film frame with soundtrack
(known as 'Academy standard') is around 1.37:1.
The 4:3 ratio for standard television has
been in use since television's origins and many computer monitors use
the same aspect ratio. Since 4:3 is close to the old 1.37:1 cinema academy
format, theaters suffered from a loss of viewers after films were broadcast
on TV. To prevent this, Hollywood created widescreen aspect ratios to
immerse the viewer in a more realistic experience and, possibly, to make
broadcast films less enjoyable if watched on a regular TV set.
16:9 is the format of Japanese and American
HDTV as well as European non-HD widescreen television (EDTV). Many digital
video cameras have the capability to record in 16:9.
Anamorphic DVD transfers store the information in 16:9 vertically
squeezed to 4:3; if the TV can handle an anamorphic image the signal will
be de-anamorphosed by the TV to 16:9. If not, the DVD player will unsqueeze
the image and add letterboxing before sending the image to the TV. Wider
ratios such as 1.85:1 and 2.39:1 are accommodated within
the 16:9 DVD frame by adding some additional masking within the image
itself.
Within the motion picture industry, the convention
is to assign a value of 1 to the image height, so that, for example, an
anamorphic frame is described as 2.39:1 or simply '2.39'.
|
|
Aspect Ratios Comparison
|
|
2.35:1
This aspect ratio offers a very wide viewable
area, and it's often used for epic movies. The real ratio is actually
2.39:1, but it's still referred as 2.35:1 due to old convention.
|
|
Below you can see the different alternatives to adapt the above picture
to other aspect ratios.
|
|
|
1.85:1 (Letterbox)
American theatrical widescreen standard,
slightly wider than the 16:9 ratio (see below).
The addition of black borders is to keep
the entire 2.35:1 picture, this process is called letterbox.
|
|
|
1.78:1 (Letterbox)
The 1.78:1 ratio is better known as
16:9, this is the one for the HDTV standard and widescreen televisions.
The addition of black borders is to keep
the entire 2.35:1 picture, this process is called letterbox.
|
|
|
1.33:1 (Letterbox)
The 1.33:1 ratio is better known as
4:3, the standard television ratio used by computer monitors as
well. This aspect ratio is used since old 35 mm silent films.
The addition of black borders is to keep
the entire 2.35:1 picture, this process is called letterbox.
|
|
|
1.33:1 (Anamorphic
Widescreen)
Technique for capturing a widescreen picture
on standard 35 mm film. To do so, an anamorphic lens is used during
recording; stretching the picture vertically so that it fills the available
film area, providing an increased quality.
Certain DVDs use this method, and since
DVD players are aware of its usage, they automatically adjust the image
to restore the proper aspect ratio accordingly to the TV aspect ratio
used.
|
|
Pan and Scan
|
|
Pan and Scan is a method of adjusting
widescreen film images so that they can be shown within the proportions
of an ordinary TV screen, by cropping off the sides of the original widescreen
image.
This is considered destructive to the directors
original vision and intentions, because it can remove up to 45%
(on 2.35:1 films) of the original image, and hinder the viewer's understanding
of what's happening.
The Pan and Scan method also allows the maximum
resolution of the image, since it uses all the available video scan lines.
This is specially important for NTSC and PAL television, that has a rather
low number of lines available to begin with. It also gives a full-screen
image on analog television. For this reason, Pan and Scan versions of
DVDs are often called Fullscreen.
Certain software
video players (such as RadLight and
Media Player Classic) have a so-called 'pan and scan' feature,
which consists basically in enlarging or reducing the video size to reduce
the black borders from widescreen videos shown on 4:3 displays such as
normal monitors and TV sets. There is no actual 'pan' process because
the borders are cropped equally on both sides constantly.
|
|
|
|
Questions? Comments?
|
|
|
If you have any questions or need support
regarding this guide or article, don't hesitate to ask at the
DivXLand.org forum personally. |
|
|
