aspect ratios

AF
Posted By
angus_farquharson
May 12, 2005
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215
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where do the pixel figures come from i.e 720 x 576 for PAL? are they just arbitrary figures chosen to represent a ratio. I presume 720 x 576 = 4×3 aspect ratio…TV sets after all come in different sizes so an absolute pixel figure would be useless…right?

angus
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SpaceGirl
May 12, 2005
wrote:
where do the pixel figures come from i.e 720 x 576 for PAL? are they just arbitrary figures chosen to represent a ratio. I presume 720 x 576 = 4×3 aspect ratio…TV sets after all come in different sizes so an absolute pixel figure would be useless…right?

angus

720 x 576 is the pixel size of a DVD… Uhm google for TV resolution.
LM
Lynch_Mike
May 12, 2005
nope. The pixel size (quantity) is an exact number despite different size screens.
JO
Jim_Oblak
May 12, 2005
This is why PPI is a bit of a bogus measurement for screen display.

Also note that you might be working with non-square pixels: so be careful with aspect ratio math.
DM
Don_McCahill
May 12, 2005
TV sets after all come in different sizes so an absolute pixel figure would be useless…right?

Not really. Different sized TV sets just have different sized pixels (san lines, actually). A small size set has the lines closer together, which is why they seem so sharp, and when you get close to a big screen, things look fuzzier. It tends to even out because people tend to back away from larger screens.

(Of course this does not apply to high definition TV systems).

Don

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