[opendtv] Re: Definition of Anamorphic
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: "opendtv@xxxxxxxxxxxxx" <opendtv@xxxxxxxxxxxxx>
- Date: Tue, 6 Oct 2009 15:58:26 -0500
Mark Schubin wrote:
>> I believe that DVDs are encoded as 720 X 480, at least
>> in Region 1. That translates to 1.5:1 aspect ratio.
>
> No. That translates to a horizontal-to-vertical active
> sample ratio of 1.5:1.
Poor choice of words. I meant to say, that would translate to an aspect ratio
of 1.5:1 were the pixels meant to be square.
The point of my thesis remains the same. Which is, pixels in the DVD format are
never square, whether for 4:3 or for 16:9 content. So that the term
"anamorphic," when related to DVD content, cannot mean distorted with respect
to a square pixel frame.
It must indicate, instead, "distorted with respect to a 4:3 frame, requiring
the compensating distortion in playback."
> FYI, when an anamorphic lens is used on film, there is
> greater vertical resolution in the displayed image than
> horizontal
Also true for "anamorphic" DVDs. The horizontal dimension in playback is
created from fewer pixels per unit length than the vertical. I'm talking about
source data pixels here, not diplay system pixels.
Bert
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