|What is Anamorphic Widescreen DVD?
Widescreen televisions can "blow up" standard, letterboxed (non-anamorphic) films so they fill the entire screen. This means that with widescreen TVs, you don't see the the black bars on the top and bottom or you see smaller black bars. The problem with this is that when you blow up the image, the picture quality goes down.
This is because when you blow up a picture to a larger size, the elements that make up that picture become bigger and more visible. In the case of televisions, the most important elements make up the horizontal resolution. This has nothing to do with the television; it's about the horizontal resolution of the image itself.
To make widescreen films look better on widescreen televisions, you need to add more lines of horizontal resolution and avoid blowing up the picture. Anamorphic widescreen DVD does both of these things.
When studios make an anamorphic widescreen DVD, they take the widescreen image and "squeeze" it horizontally, so the entire width of the image fits into a 4:3 aspect ratio.
Squeezing the image this way increases its horizontal resolution, because the black bars used in letterboxing can be much smaller, if they're needed at all. The black bars at the top and bottom that would be visible with standard letterboxing are "squeezed out" and everything in the picture is taller and skinnier.
Widescreen televisions take the squeezed image from the anamorphic widescreen DVD and stretch it horizontally. This restores the proper aspect ratio of the image.