I think it's done for the same reason they do it with film; to get a wider aspect ratio on the existing format. It allows them to use more of the "image area" (only electronically) to show 1.85. It's not just a buzzword.
If you were to watch the disc without the automatic unsqueeze, it would look like a scope movie projected with a flat lens and scope plate.
(Good God, three answers at the same time! And yes, the widescreen televisions will unsqueeze this sideways and eliminate the letterbox.)
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John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion
Enhanced for widescreen TVs
Enhanced for 16:9 TVs
Anamorphic video
Anamorphic 1.85:1
Anamorphic 2.35:1
are used. There may be others. In the early days of DVD, many disks were not anamorphically encoded. To make matters worse, there were some disks that had packaging indicating anamorphic transfers, but weren't, and some disks were anamorphic, but the packaging did not mention it anywhere.
As people have stated before, DVDs have a resolution of 720 by 480, and that resolution can fit either a 4:3 (1.33:1) area or a 16:9 (1.78:1) area. In neither case are the pixels square.
For 4:3 material on a 4:3 set, the 720 by 480 resolution is fit into a 4:3 rectangle, using the entire screen. (Duh)
For 16:9 material on a 4:3 set, the 720 by 480 image is converted to a resolution of 720 by 360 for display, which produces a 1.78:1 image on the 4:3 set (remember, the pixels aren't square).
For 16:9 material on a 16:9 set, the 720 by 480 image is fit into a 16:9 rectangle, using the entire screen. (Duh)
For scope movies, unfortunately, rather than having a different anamorphic squeeze factor, the 2.39:1 image is letterboxed into the 16:9 rectangle (a 720 by 327 image), which gets converted down to a measly 720 by 268 for viewing on a 4:3 set). Most flat movies are probably transferred at 1.78:1 rather than being slightly cropped to 1.85:1.
The anamorphic squeeze factor for DVD is 1.33, which is much more gentle than film's 2:1.
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Evans A Criswell
Huntsville-Decatur Movie Theatre Information Site
Now what I just said isn't quite the whole story, because on every player I've seen, there is more than just the option to tell it whether you have a 4:3 or 16:9 TV. There are always three options. 16:9, 4:3 letterbox, and 4:3 full frame. I'm not sure what the difference is between those last two, as they both appear to have the exact same effect. As long as you choose one of the two "4:3" options, and it doesn't seem to matter which, 16:9 enhanced discs will show up correctly on your display.
It seems the distinction between the two 4:3 options stems from part of the DVD standard that so far has not been used by any discs in circulation. This question in the "official" DVD FAQ gives a bit more info. It talks about "automatic pan & scan mode" for 16:9 video on 4:3 screens, which is probably why there are two 4:3 options on most players rather than just one, but as far as I know, there are no released discs which use this, so it really doesn't matter which of the two 4:3 options one chooses. They will both have the same effect.
Now, when it comes to labelling, I think they should avoid the term "anamorphic" on DVD covers altogether. Why? Because, as Evans pointed out, in a sense, all DVDs are anamorphic. That is, the pixels are always non-square. If you were to consider the pixels of a 720x480 image to be square, its aspect ratio would be 3:2 (1.5:1). No television in the world is that aspect ratio! So, in the case of 4:3 video, the image must be slightly squeezed in the horizontal direction in order to make it fit. And in the case of 16:9 video, it must be slightly stretched in the horizontal direction in order to make it fit. In both cases, the image is "anamorphic". So, it is misleading for the packages to say "anamorphic" in some cases and not in others. Instead, they should say "enhanced for 16:9 TVs" in cases of 16:9 discs, and nothing at all in the case where it is 4:3. A few discs do actually use this labelling scheme, but most do not.
Here is a little more info:
http://gregl.net/videophile/anamorphic.htm
Here is what we knew then, and I am sure it applies now, about DVD's.
1. there are two kinds of widescreen presentations,
a. ANAMORPHIC
b. LETTERBOXED
When a DVD is letterboxed, it is presented in its theatrical release format, but on a 4:3 or television frame with the black bands at the top and the bottom. You see the same thing on some flat prints that are HARD MATTED. This means that the top and bottom of the frame are cut off. If you show it on a 16:9 screen, you will have to zoom in to make it fit the screen, as it is encoded at 4:3 with the bands at the top and the bottom, resulting in lower resolution.
When a DVD is in an ANAMORPHIC ratio, and it can be at this in the 1:85 or 2:35 or whatever format, it actually takes the entire image and compresses it into the 4:3 tv screen. Your dvd player will automatically be set to to the 4:3 tv screen, and will decode the film appropriately. You will see it in the correct format. If you have a 16:9 screen, you then tell your DVD player to compensate in its settings, and you will fill the screen, with much better resolution than the letterboxed version, because it uses all the pixels to create the image, and has no black bands at the top and bottom. In anamorphic DVD's the black bands you see at the top and bottom on your 4:3 screen are placed there by the DVD player, and not encoded into the DVD itself, as it is with letterboxed.
WITH THIS IN MIND...
it is really necessary to know if a DVD is anamorphic or letterboxed.
Anamorphic = more resolution
Letterboxed = less resolution
Theres my two cents, and now I am broke.
Dave