John nailed it. The term "anamorphic" originated with film (CinemaScope?) where the camera lens and the projector lens were compliments of each other, so that by using the standard 35mm frame rectangle, a much wider image could be recorded and reproduced. In essence the same number of "pixels" (silver grains) are used to represent a wider image.)
If an anamorphic film were projected using a non-anamorphic lens, the resulting image (I won't say 4:3 because I don't know the precise aspect ratio of a standard 35mm film frame and I am too lazy to look it up, but it's darn close to 4:3) the images are horizontally squeezed so that people look unnaturally tall and skinny, and a circle would be a vertical oval.
In video, a 720x480 frame can either be 4:3 aspect ratio or 16:9 aspect ratio. If the image was captured as 16:9, when it is subsequently displayed on a 4:3 monitor the images will have the same horizontally squeezed look. However, examining the video signal (analog NTSC or SD-SDI digital) line by line, frame by frame, pixel by pixel, it is impossible to distinguish 16:9 material from 4:3 material. It isn't until you actually view it on a display can you tell that the image is right or wrong.
The term "anamorphic" has become standard industry practice to refer to just such a 16:9 aspect ratio image that is presented in 720 (or 704)x480, either i or p. I can point to countless video camera instruction manuals that use the term "anamorphic" when referring to recording in the 16:9 aspect ratio. The term "anamorphic widescreen" is also used by the DVD industry. Wiki has an excellent article on the subject.
Therefore, when an image is intended to be viewed in a 16:9 aspect ratio, and the active video occupies the entire 720x480 frame, I refer to it as "anamorphic 16:9" to distinguish it from an image intended to be viewed in a 4:3 aspect ratio, and the active video also occupies the entire 720x480 frame.
Since both 1280x720p and 1920x1080 i or p video is always 16:9, it is not standard industry practice to refer to it as "anamorphic." The term "anamorphic" is reserved for those formats that have more than one "native" aspect ratio, such as 720(704)x480.
John----- Original Message ----- From: "John Willkie" <johnwillkie@xxxxxxxxxxxxx>
Could you provide us with an ATSC or MPEG-2 definition of this "anamorphic?" It's a term used in the DVB world, but not so much in the ATSC one, so "you"are the one saying that a program is transmitted anamorphic. I'm familiar with the film term anamorphic; a pickup and complementary presentation lens that distort the aspect ratio. I don't think you are talking about lenses.
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