Quote:
Originally Posted by eiren You're referring to anamorphic stretching, but that wouldn't apply in the case above... surely? |
No, I'm not referring to anamorphic stretching. As you state, that does not apply here (at least not in the strict 4:3 to 16:9 sense we're used to).
Anamorphic stretching is a reference back to anamorphic lenses used in cinema. In order to achieve a wide field of view and record it in the highest quality they used lenses which, put simply, squeezed a wide "oblong" of view along the horizontal axis to record it onto a "square" film frame - using the full height of the frame. This was played back in the cinema through a similar lens to create a wide image.
When widescreen TV broadcasting started they used a similar approach and squeezed wide programmes into "square" SD broadcasts. Your widescreen TV then did the anamorphic stretch to undo this and recreate the original 16:9 image. Some people leave this on (when they shouldn't) for normal 4:3 broadcasts - resulting in fatty-vision
[I'm ignoring the cerebral issue about whether or not the broadcast of a series of electronic values (analogue or digital) is truly "square" or "rectangular" in nature]
With HD the broadcast is already deemed to be 16:9 and so no "un-squeezing" is required.
[Although you could argue that spreading the incoming image details over a 16:9 screen is in essence the same as un-squeezing a 4:3 image]
What we're talking about here is
slightly different (although quite similar).
The native resolution of an HD broadcast can vary. No matter how many (or few !) pixels, nor what "shape" they take, the image is deemed to be 16:9 in shape. The Sky box will create a 1920x1080 image from this image to send to your TV.
Upon reflection, the
addition of pixels to fill out the 1920 "across the way" requirement is pretty much the same thing as anamorphically stretching the incoming picture actually. So perhaps I am being unduly picky.
The important thing is that HD broadcasts are often made with a resolution less than 1920 ... and do not result in black "pillar box" bars.
Regards