Is 540p the same quality as 1080i??? - AVS Forum
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Old 01-12-2002, 11:30 AM - Thread Starter
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I am looking at a TV that is 540p capable, but I need to know if I should stay with a set that's 1080i. I realize that most programming out there is 1080i so the tv would have to convert everything to 540p, RIGHT??? I will also be running an X-Box in to it and some of those games are 1080i......


Thanks in advance,
Mike

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Old 01-12-2002, 01:42 PM
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540p and 1080i are close cousins, but 1080i definately has more detail at twice the verticle resoulution. Most 1080i sets will also do 540p as they use the same sync timing.
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Old 01-13-2002, 06:12 AM
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You have to factor in the original source of a 540p signal, too. Tuner/decoders such as the vintage RCA DTC100 can upconvert standard 480i NTSC signals to 540p for display. Some current HDTV sets also perform this upconversion. But the images displayed were originally scanned at ~480 active (visible) lines.

A 1080i signal originating with a HDTV camera or film scanner (telecine) starts with 1080 visible scan lines and more horizontal resolution. But when motion occurs in 1080i HDTV scenes, as a section on resolution of this ATSC report points out, the scenes appear the same as when they're displayed at 540p. A while back I simplified measured resolutions from this report (my 8/22 post) .

Electrically, to the drive circuits of HDTV displays, 1080i and 540p also appear the same. This can simplify set design and reduce costs if only one sweep rate is needed. So more HDTV manufacturers are upconverting 480i to 540p. -- John
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Old 01-14-2002, 09:44 AM
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Was wondering, what resolution would the human eye be capable of? Or is that a stupid question? 2160i? 4320i?
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Old 01-14-2002, 03:08 PM
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There are no stupid questions.

As for the answer remember that the most important thing is the distance from the display to your eyes. A 20/20 vision is computed based on the resolution of your eyes at a specific dinstance. Now if someone can calculate what 20/20 vision corresponds to in terms of distance and resolution that would be cool.
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Old 01-15-2002, 06:52 AM
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Quote:
Was wondering, what resolution would the human eye be capable of?...2160i? 4320i?
Don't have a ready answer, but recall some snippets from various threads that are indirectly relevant. This range of vertical resolutions, assuming an equivalent or greater range of horizontal resolution, is typical of some JVC D-ILA panels for projectors that been demonstrated or are under development. They're aimed initially at theater and industrial use. Such projector systems, with no moving parts except for hard-disc drives, can put such high resolutions on screens.

By contrast, although the initial negatives shot for movies may have resolutions matching or exceeding these numbers, copies made for mass distribution sharply cut resolution. Then, when this reduced-resolution film is run through theater projectors, the mechanical 'jitter' further diminishes resolution. Details on screen may actually be worse than the best HDTV available in homes.

Also, for about $20k, IBM will sell you a LCD monitor with such exceptional 9+ megapixel resolution. They just got an award for the display, described here (about 1/3 down, or search for "Model T220.") It's meant for commercial/industrial use, such as displaying photos. And someone in the CRT forum recently mentioned routinely working with such resolutions related to X-ray images. -- John
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Old 01-15-2002, 08:41 AM
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As I understand it, the human eye contains approximately 6 million cones and 120 million rods. The cones are mostly responsible for everything but peripheral vision. Also, the human eye can discern 1 minute of arc separation. That should give enough information to figure out the resolution of the human eye, but it is unlikely to be as simple as that, I would guess.

David S.
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Old 01-16-2002, 02:19 PM
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michaeldare, what TV is it exactly? It probably displays BOTH 540p and 1080i since they are the same frequency. The TV would 'see' them as being pretty much identical.
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Old 01-16-2002, 02:38 PM - Thread Starter
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John,


I did some further research after reading some of these posts. It's the Toshiba 50X81 and it does support both 540p and 1080i. The first page I saw on it only stated 540p.



Thanks for the replies,
Mike

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Old 01-18-2002, 10:20 AM
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D = H * 3438 / V

D is the distance from a screen of height H at which normal eyes can resolve at most V lines of vertical resolution.

Example:
A particular screen has a height of 30 inches.
It is displaying an image with 1080 lines of vertical resolution.
D = 30 * 3438 / 1080 = 95.5 inches = approx. 8 feet
So you can see all 1080 lines only if you are located no farther than 8 feet from the screen.

Variations of this equation may be useful.

V = H *3438 / D

H = D * V / 3438
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Old 01-18-2002, 11:23 AM
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Does the TV actually display 540P or is it able to accept a 540P signal and then convert it to 1080i for display?

Ron
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Old 01-18-2002, 02:29 PM
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Quote:
Originally posted by Ronald K
Does the TV actually display 540P or is it able to accept a 540P signal and then convert it to 1080i for display?

Ron
I believe the HDTV Monitor would display it natively.

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Old 01-18-2002, 03:27 PM
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540p is just a single field of 1080i.

Think of it this way: A regular NTSC TV can output 240p, which is a single field of 480i. In fact all the early console game systems up to the Playstation (and most playstation games) output 240p only.

I seriously wouldn't mind if 540p became the standard for SDTV (for news broadcasts and other things that are not detail oriented) rather then 480p/i. I don't know if it's in the ATSC specs though.
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Old 01-18-2002, 04:02 PM
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Nope, 540p is not in the ATSC standard, but it is in the CableLabs spec for advanced cable set-tops. Any 1080i capable TV should have no trouble with a 540p signal.
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Old 01-18-2002, 06:26 PM
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Quote:
540p is just a single field of 1080i.
Don't believe that's quite right. A single field of 1080i has half the lines, or 540, but in viewing both 1/60-sec 540 fields our eyes merge them together into a 1/30-sec frame. A single field is only half the image.

In the ATSC report section I mentioned earlier, they said 540p appears very similar to 1080i when motion is occuring. But that 540p image must be presented each 1/60 sec to duplicate the content of two visually merged fields creating a 1/30-sec HDTV frame. 'Course that's just my opinion. I could be wrong. -- John
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Old 01-18-2002, 07:31 PM
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Comparing 540p to 1080i is analogous to comparing 240p to 480i.

I can easily notice the difference between 240p and 480i on a regular NTSC TV. Besides the difference in resolution, there are just certain artifacts (flickering, jaggies, feathering, etc.) that are inherent to interlacing regardless of the resolution.
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Old 01-20-2002, 07:02 PM
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John Mason

Your clarification doesn't disagree with me ;) If you're talking about timing issues, then yes a single field of 1080i would only be output at 30Hz. I meant the difference between 540p vs. 1080i from the CRT's perspective (which is basically nil).
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Old 01-21-2002, 09:42 AM
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Agree, roman, that timing is a key consideration. (BTW, a single field of 1080i would be output in 1/60-sec.) Think it's also important not to mix concepts of 540p produced from non-HDTV sources (a DTC-100 upconversion, for example) and 540p related to true-HDTV (1080i) analysis. For example, the FCC's experts, here , refer to the diagonal resolution of a 1080i image as being the vector sum of the horizontal and vertical resolution (540 in their table 2.3). Also, they mention, "In the case of an interlaced scanning system, for vertical resolution under motion, the picture will take on the characteristics of a progressively
scanned system with half the number of scanning lines (i.e., vertical resolution of 1080I becomes 540P under motion)." -- John
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Old 01-21-2002, 09:53 AM
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Quote:
(i.e., vertical resolution of 1080I becomes 540P under motion)." -- John
Which is why 720p is so much better for sports than 1080i.
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Old 01-22-2002, 02:49 PM
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A good Visual ...

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Old 01-22-2002, 05:57 PM
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I created an image to compare the resolutions of 540p, 720p, and 1080i.
LL
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