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A closer look at Aspect Ratios (divxstation)
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The way in which movies are presented on DVD can be a source of confusion. There are various terms such as "enhanced for widescreen TVs", "pan and scan", figures such as 4:3, 1.85:1 etc. that may be used on the DVD packaging to explain how the movie is presented on the disc. The following will attempt to explain the differences in presentation and show how they look on both standard and widescreen televisions.
The Different Ratios
The ratio of width to height is often quoted when dealing with different methods of movie presentation. A standard TV screen has a ratio of 4:3 i.e. for every 4 units wide it is 3 units high. This ratio is sometimes quoted as 1.33:1 which is exactly the same as 4:3. Widescreen TVs are obviously wider and their screens have a ratio of 16:9 i.e. for every 16 units wide they are 9 units high. This ratio is the same as 1.78:1.
Movies shown at the cinema are filmed in a variety of ratios but the most common are 1.85:1 and 2.35:1. When these movies are shown on a standard TV in their original format (i.e. preserving how they were shown in the cinema) the picture appears letterboxed, with two black bars at the top and bottom. The bars are larger when 2.35:1 material is shown because the picture is much wider. 1.85:1 material is often cropped to 1.78:1 on DVD so that the picture fills the 16:9 screen of a widescreen TV, but this cropping does not result in any noticable loss of picture information. If the original 1.85:1 ratio is preserved the picture doesn''t quite fill the whole 16:9 TV screen. When 2.35:1 material is shown on a widescreen TV the picture appears letterboxed with two small black bars at the top and bottom - the bars are not as large as on a standard TV when 2.35:1 material is shown however.
In addition, DVD content may be presented in the 4:3 ratio, either modified from it''s original cinematic presentation (more on this later) or originally filmed in this way - older movies may not have been filmed in a wider format. If this is the case the picture will fill the screen of a standard TV but on a widecreen TV there will be black bars to the left and right of the picture, unless the image is "stretched" to fill the wider frame (most widescreen TVs have this facility).
Pan and Scan
There is a technique called "pan and scan" which is used to modify widescreen material (be it 1.85:1, 2.35:1 or any other ratio) so that it fills the whole screen of a standard TV. Rather than just take the middle of a widescreen picture and crop the sides, the pan and scan technique takes a centre of interest which may not necessarily be the middle of the picture. The 4:3 "window" can be moved around the widescreen picture so that important information is not missed. However, the result of the pan and scan process if often not satisfactory and the viewer ends up missing a lot of the picture.
Some people like movies to be panned and scanned so that they don''t have to view them letterboxed, but others prefer to see the movies as they were shown in the cinema i.e. letterboxed on standard TVs, which is why many DVDs have both the pan and scan and widescreen versions of the movie on the same disc. When there is a pan and scan version present on the disc the DVD packaging usually states that the movie has been "re-formatted to fit your TV screen", or something similar.
Enhanced for widescreen TV's
Many DVDs have the statement "enhanced for 16:9 widescreen TVs" or "anamorphic widescreen" on the packaging. What this means is that the widescreen picture has been stored on the disc in a way that gives a better quality picture than normal (consisting of a greater number of lines) when viewed on widescreen TVs - the DVD presentation is said to be "anamorphic".
Normally, when widescreen movies are stored on VHS, Laserdisc or non-anamorphic DVDs the image is shrunk until it fits inside a 4:3 frame. This means the black bars are stored as well, taking up horizontal lines that could be used for the actual picture. With anamorphic DVDs the widescreen picture is first "squashed" to fit into the 4:3 frame without black bars and then this is stored on the disc i.e. all the horizontal lines are used for picture information. When shown on widecreen TVs the picture is restored to it''s original aspect ratio and is of higher resolution because a greater number of lines have been used. For standard TVs the DVD player restores the picture to it''s original ratio, creates the two black bars and adds them to the image which is then displayed. Therefore, the picture from a DVD that is "enhanced for widescreen TVs" will be of higher quality when displayed on a widescreen TV than a DVD that is not enhanced.
-Richie Rags |
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Published on 23-01-2003 |
