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admin's picture
Last seen: 3 days 19 hours ago
Joined: 04/09/2013 - 14:19
Posts: 51588
1080i and 720p

Please help! I have a 46inch rear projection DLP. It's a 1280x720. The book says I can receive 1080i, so does Toshiba. But retailers tell me that it is the 720 that counts and not the 1280. I have read many articles on HD TV and they are not clear. If TVs scan at 720 then why don't they call them 720 sets instead of 1080i sets? And if they scan at 720 horizontal lines what are the 1080i verticle lines doing? And what about 24fps? Our TVs already deliver 50hertz. Newer models now boast 100hertz. I know about full HD 1920x1080p but as we cannot receive this from Sky etc. I am not bothered by it. Can someone please explain? By the way, no matter what they are called, I have an absolutely stunning HD picture on my Toshiba. Paul Dardis.

Andrew Everard's picture
Last seen: 4 years 3 months ago
Joined: 30/05/2007 - 12:34
Posts: 28828
Re: 1080i and 720p

The 720 or 1080 refers to the number of horizontal lines. Your TV has 1280 pixels in the horizontal axis, and 720 in the vertical, so that means 720 lines maximum resolution.

It will accept 1080i signals, but will downscale them to 720 lines, progressive scan - ie 720p.

They don't call them 720 sets because bigger numbers sell. They call them HD Ready instead.

100Hz? Some swear by it, some swear at it. Why's it there? See my earlier answer about HD Ready.

24fps is to do with the ability of Blu-ray players to show movies at their original frame-rate, not slightly speeded up to match a 50Hz TV's scanning rate. Not all TVs can accept this at its native speed, and some show some juddering when showing this kind of signal.

However, unless you're hugely troubled by judder, I wouldn't worry about it.

Anonymous's picture
Re: 1080i and 720p

Thank you for your reply, but your first two sentences are a bit confusing. Is it not 1280 vertical and 720 horizontal?


professorhat's picture
Last seen: 1 week 5 days ago
Joined: 28/12/2007 - 11:34
Posts: 11051
Re: 1080i and 720p

Nope, 1280 along the horizontal axis and 720 along the vertical axis - this gives you 720 horizontal lines and 1280 vertical lines.

The owls are not what they seem...

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