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February 8th, 2013, 05:47 AM | #16 | ||||||||
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Re: 1080 vs 720, i vs p
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Also, 1080p is compressed more than 720p, even on the web. This 'extra' compression reduces perceptible resolution. It's all about perception. Quote:
No rocket science, just basic trigonometry. Hope this helps.
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February 11th, 2013, 03:29 AM | #17 |
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Re: 1080 vs 720, i vs p
That was a wonderful answer, Sareesh. Really appreciate it!
I'll check out your blog now and add it to my RSS feeds :) |
February 13th, 2013, 11:50 AM | #18 | |
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Re: 1080 vs 720, i vs p
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It's easy enough to show. For the 720p, 50" TV he refers to, that will be 50" across the diagonal, so for 16:9 aspect ratio, that gives a height of 30" and a width of 40". (By Pythagorus theorem.) Now if it's 720p, there must be 720 pixels vertically in those 30", or 24 per inch, which equates to a pixel spacing of 0.042" - NOT 0.034". I agree with his other figures about the limiting resolution of a typical human eye (1 minute of arc, or 0.035" at 10 foot viewing distance), but that means the eye is capable of resolving more detail than a 720p screen is capable of giving at that distance. Redo the figures with 1080p, and 1080 in 30" means 36 per inch, or a spacing of 0.028". So better than human vision. And that's the maths and science behind why 720p is not good enough for 50" screens at normal viewing distances, whilst 1080p is generally regarded as OK up to about 60". In ball-park terms, at 10 foot viewing, 720p is normally regarded as good enough up to about 37-40" screens, but you'll see an improvement with 1080 with bigger screens. 1080p should be good enough up to about 50-55" - bigger than that, and there will be a noticeable difference with 4k. Practically, it's better to oversample, rather than be right on the resolution limit, for reasons so 4k may start paying dividends even around the 50" mark. Certainly the CNET conclusion (".....at 10 feet, your eye can't resolve the difference between otherwise identical 1080p and 720p televisions") is simply not true. |
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February 21st, 2013, 03:47 AM | #19 | |
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Re: 1080 vs 720, i vs p
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As web delivery of content by broadcasters becomes more and more significant (and in the future may well overtake traditional broadcasting over the air) less and less interlace will be used. The majority of HD content is watched on progressive display devices that have to use tricks like bob-deinterlacing. Many productions are edited on computer systems that only have progressive computer monitors for display. I think that interlace is something that will gradually disappear.
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February 21st, 2013, 04:15 AM | #20 | ||
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Re: 1080 vs 720, i vs p
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I agree with you about intelacing disappearing. The UHDTV standards make no room for it.
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February 21st, 2013, 08:33 AM | #21 |
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Re: 1080 vs 720, i vs p
I wonder when we will actually move to true1920x1080 50/60P since almost all the consumer cameras can now do this as well as my latest GoPro !!! There is a difference and it would make display a lot easier.
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February 21st, 2013, 02:50 PM | #22 |
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Re: 1080 vs 720, i vs p
Sareesh, Paragraph 2:1:1 Material may be originated with either progressive or interlace scan.
If you shoot progressive and place it in an interlaced stream what do you get? PsF. An interlaced master that contains progressive material is PsF, the content on the tape is still progressive, it hasn't become interlaced, its still progressive, only the single progressive frame is now split into odd and even lines. The temporal motion of the footage is still the same, there is no temporal difference between the fields. The delivery master may well be a tape or file that has 50 fields per second, but if the two fields contain odd and then even lines from material that was originated progressively, then this is PsF. Most BBC documentary production is progressive, almost all drama is progressive.
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February 21st, 2013, 09:29 PM | #23 | |
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Re: 1080 vs 720, i vs p
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February 22nd, 2013, 03:33 AM | #24 |
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Re: 1080 vs 720, i vs p
Agreeing, if we both agree that the BBC do accept productions that are shot, edit and produced in progressive. It is only the delivery file or tape that must use PsF. As PsF is still progressive, then the BBC do accept progressive files, you just can't send them a straight from the camera 25p frame only file.
To me your original statement sounded like you we're saying the BBC don't accept progressive programmes.
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February 22nd, 2013, 06:03 AM | #25 |
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Re: 1080 vs 720, i vs p
Not at all. We agree 100%!
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February 25th, 2013, 04:43 PM | #26 | ||
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Re: 1080 vs 720, i vs p
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A 16:9 ratio display the sides can not be 3:4 with a hypotenuse of 5. @16:9 ratio the sides will be 24.5" and 43.6" with a diagonal of 50". And 720 pixels over 24,5" gives a pixel size of 0.034" Quote:
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March 3rd, 2013, 12:06 PM | #27 | |
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Re: 1080 vs 720, i vs p
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If I have any excuse, it's that my (incorrect) working seemed to agree with conclusions that have been generally found in practice, so maybe I didn't check the figures as closely as if they had seemed to show something surprising. As illustration, the best research I've come across was done a while back by BBC R&D and is online at http://downloads.bbc.co.uk/rd/pubs/w...les/WHP092.pdf . Then, they came to the conclusion that 720p should be good enough for general broadcast - but were basing that on the assumption that screen sizes for the home were likely to be around 37" typically, up to about 42" max. In practice, that was very pessimistic, home screens are often larger than 42" now and the conclusion was out of date almost before the document was published (though not the test results). Look at figure 9 and it shows that up to a 40" screen only 15% of observers could see a benefit to 1080 over 720. That increases to nearly 30% for a screen size of 42" and nearly 50% for a 50" screen. |
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March 4th, 2013, 04:18 PM | #28 |
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Re: 1080 vs 720, i vs p
I was lucky enough to spend a weekend using an 84" 4K Sony Bravia to show and demo some 4K footage and HD footage.
Up close (within 4m) the difference between the 4K and HD was clear to see, but further away the difference became harder to see. 4m is pretty close to such a big screen. However, even when at the back of the room, about 8m to 10m away there was something incredibly "real" about the 4K image that wasn't there with HD material. I would not say the footage looked sharper, or that I could see more detail, but many in the room could sense something different about the footage when it was shown as 4K compared to HD. It really was like looking out of a window. Perhaps it was just the scale, but I've never had such a distinct sensation of looking out of a window with 4K projection. I get to play with the TV again next week at CabSat.
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