Vim & Vision
[ #223 ] TV Aspect Ratios Permalink
NB: This post was written for my mum :-) It is based on Australian information, it most likely applies to everywhere else but I don't know.
If you own an HDTV you might be wondering about black lines. Your experience might be something like this:
- TV station promos and new television shows take up the whole screen
- Old TV shows have vertical black lines
- DVDs still have horizontal black lines
- Some advertisements have horizontal black lines
Why, I hear you ask?
All Australian digital TV is broadcast at the 16:9 ratio. This is the ratio of your new TV. All new TV shows and promos are filmed at this ratio. This is why new TV shows take up the whole screen on your new TV.
When you see an old TV show (or an old movie on TV) you will notice vertical black lines down the sides because these shows were filmed at the 4:3 ratio. The picture that is being broadcast by the digital TV station is still actually 16:9 (it always is) - the black lines are actually being sent to you as part of the picture. Obviously it still must be presented to you at 4:3 because we can't go back in time and add new information to the recording... and if we stretch it out to fit on the screen horizontally then the picture will be warped.
When you play a DVD through your new TV you will notice horizontal black lines on the top and bottom because, while the DVD is indeed presented at 16:9, the film was originally shot at a ratio something like 2.40:1 (or maybe 2.35:1) and shrunk down to fit to 16:9. Why don't they crop the film down to real 16:9? Because horizontal strips of information at the sides of the film would be lost.
What about ads? Sometimes a brand new ad on a brand new HDTV will still display with horizontal black lines. This is because some ads have been made to purposely have the black lines for visual effect - to make their presentation appear more cinematic.
Colophon
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