Ed's View - HDTV Quality Reduction - A Time for Action

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miller
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Re: What's the Problem?

Post by miller »

[email protected] wrote:First of all, you have to have a screen larger than 50" to see the full 1080p resolution anyway unless you sit closer to the screen than one would normally comfortably view a TV set. Paying for 1080P with a 50 inch or less screen is probably a waste of money. So unless you have a very large display, you'll never notice a quality problem with any source 720P or greater.
All subjectivity aside, there is one thing you may not have considered: Scaling artifacts. If you watch a lot of 1080 source on a 720p set, everything will be down-converted to 720, which will produce visible artifacts at any screen size.

So while most may not get the benefit of 1080p on smaller screen sizes, you won't have the visual artifacts related to downrezzing.

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Thanks for the Heads-up!

Post by hharris4earthlink »

Downsizing artifacts is something I did not know about and has not appeared in any of the technical reviews I've read, although I can certainly see how it's possible. Thanks for the heads-up!

Can you give me a technical reference to this problem? I'm afraid I'm just a physicist so I'd be interested more in first principles.

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Post by Richard »

viewtopic.php?t=5479
FPD is what it says, fixed pixels and that means it cannot change to any other scan rate than what it was designed for.
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Post by hharris4earthlink »

Okay, but when I download movie previews from the Internet using my PS3 with an option of 1080P or 720P I can't really tell the difference between the two on my 720P Samsung display. The artifact phenomenon must very minimal or I don't know what to look for. I was expecting some small difference in edges of letters but they looked clean in both images.

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Post by Richard »

They may call it 720p but chances are it really isn't. What is the model number?
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Post by hharris4earthlink »

Yes, my understanding is it could be 768p. 720p is sort of a shorthand. It's a HP-T6054 Samsung.

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Post by Richard »

That model gets 0 hits on Google... but since you suggest 768p...

If a fixed pixel display is not exactly 1280X720 or 1080X1920 then you will never get the locked in detail response that only comes with 1:1 pixel mapping. Your comparison of 720p versus 1080i/p is invalid because you are always looking at the scaler. All you can do without test patterns is subjectively guess which one performs better with that scaler.
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Oops!

Post by hharris4earthlink »

Sorry, I transposed two digits. It's really a Samsung HP-T5064. So, is looking at the scaler inherently lower resolution, are does the larger number take care of that?

A site that discusses this model is

http://reviews.cnet.com/flat-panel-tvs/ ... l?tag=coco

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Post by Richard »

Yep, the typical 1366X768. The mismatch causes a filtering effect as your scaler attempts to fit a square peg in a round hole forcing a loss in detail.

Go to the Overscan section and look for a picture comparing two sets of lines
http://www.hdtvmagazine.com/reviews/200 ... jector.php
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An outstanding OTA broadcast: not to be missed

Post by andrewleblanccox »

I have both Blu-Ray, Toshiba HD, Direct TV, and OTA reception of all the networks. Generally, the OTA, Blu-Ray, and HD discs are
comparable. Depending on the transfer, some movies on Direct TV look look almost as good as the disc versions. A recent broadcast
from the PBS HD Channel which has blown away anything I've ever seen on OTA is the Oscar winning short animated film, "Peter And
The Wolf" with music by Prokofiev. It repeats on Friday, March 28, at 11 am Eastern. This is a real show off for any system and is not
to be missed. The DVD is forthcoming, but is only in SD.
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