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post #1 of 15 Old 10-02-2013, 01:07 PM - Thread Starter
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I thought I might ask this question as I'm curious as to what the answer is. I know that when the resolution of a display is higher, you can sit closer to it, and the opposite for a lower resolution.

I was thinking, does that same fact apply if the resolution of the content is in SD, but upscaled by the display or another source device to 1080p?


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post #2 of 15 Old 10-02-2013, 01:32 PM
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Yes it does. Depending on the quality of the upscaling device the picture might be noticably better than on an SD device, but not near as good as an actual HD-source.

If your viewing distance isn't depending on your room (or significant other), I would choose based on the content you view most often. I myself usually watch HD content on my 50" Plasma and have a viewing distance of about 6'3" (1,9m).
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post #3 of 15 Old 10-02-2013, 01:46 PM - Thread Starter
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Thanks for the reply. Just to make sure I have it right, if I watch actual 1080p content, but also watch SD content upscaled to 1080p, the viewing distance should be the same, but it also depends on the quality of the scaler?


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post #4 of 15 Old 10-02-2013, 01:54 PM
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If you watch more SD content than HD I would sit a little farther from the TV than the other way around. But I would honestly just try it, see what you like best. The better the scaler, the better the picture will look.
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post #5 of 15 Old 10-02-2013, 01:58 PM - Thread Starter
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Ok, thanks for your help Monvo.


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post #6 of 15 Old 10-03-2013, 06:48 PM
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Ehhhhhh.... I don't really subscribe to being able to sit close to higher-quality upconverted SD. It's still SD and it can't have any more detail than 720x480 which isn't very impressive when upconverted and displayed on a larger screen. Where I'd sit 7.5 feet from an 80" diagonal screen (yes. 80" not a typo), To make SD not look obviously bad on an 80" diagonal screen, 12 or 15 feet from the screen would be more like it. Poorly upconverted SD might look OK at 15 feet, but the best upconverted SD you can get (a Lumagen Radiance video processor is about as good as it gets today) isn't going to let you get much closer than 14 or 13 feet before you begin seeing lots of problems in the image. People general HATE SD on HD displays because the SD images are now typically much larger than the CRTs we used to use and the small sizes of CRTs helped hide how bad SD video was. There's really no such thing as good looking SD video on HD video displays EXCEPT computer animation from DVDs... it upconverts better than any live action SD video source including live action movies on DVD. There are times when computer animation on DVD can look pretty darn good on an HD video display, especially if a Lumagen Radiance processor is doing the conversion.

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post #7 of 15 Old 10-03-2013, 07:08 PM
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if 480i/p looks compromised on a 1080p display from too close, would 720p/1080i/p also look compromised on a UHD display at distances intended for native UHD content (aka also too close)?


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post #8 of 15 Old 10-03-2013, 07:20 PM
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Original SD NTSC television was developed for a 19" 4 x 3 CRT. Seating distance was recommended at about 8 times the screen height. Later televisions were made larger, but the resolution of the programming did not change. Laserdisc brought a slight increase in resolution. Line doublers (deinterlacers) helped a little in the latter days before DVD. DVD brought a slight increase in resolution and digital video. Anamorphic DVDs helped expand the resolution a bit more. DVD can be upscaled on HDTV displays but, as Doug pointed out, no added image content can be realized.

Many consumers watch soft images on their HD displays from SD content and don't mind the softness for the sake of a bigger picture. It is still a soft image at normal HD viewing distances (approx. 3 times screen height). Many folks sit in the front sections of commercial cinemas and don't mind the softer image for the sake of a larger picture. As I have become more and more experienced with viewing reference images over the years on the professional side of the motion imaging industries, I have found myself preferring a sharper image over a large image that is soft. I have moved farther from the screen in the cinema. To achieve the degree of image focus and sharpness the content creators intended for SD programs, a farther viewing distance on an HD display will replicate that "look." This is true for even paintings. Certain paintings are meant to be viewed from a specific distance to achieve the artist's intent.

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post #9 of 15 Old 10-04-2013, 12:47 PM
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Greetings

I recall from the old Digital Video Essentials DVD ... that Joe Kane mentioned something to the effect of 4-6 times picture height for SDTV (DVDs) ... also included the 5-7 times picture height reference as well. referred to as working distance in the disc.

I'm not sure anyone out there would change their viewing distances given the content. I haven't seen it in the 1000's of homes I've been to.

My parents traditionally sat about 12-15 feet from the Tv ... be it the old 45" Mits RPTV or the 47" Panasonic RPTV to the current 50" Plasma. That's just the way the room is and where the couch needs to sit. As the screens get larger ... they are defacto moving closer to the TV.

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post #10 of 15 Old 10-04-2013, 01:11 PM
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Quote:
Originally Posted by PlasmaPZ80U View Post

if 480i/p looks bad on a 1080p display from too close, would 720p/1080i/p look bad on a UHD display at distances intended for native UHD content (aka also too close)?
"Bad" is a strong word for such considerations. "Compromised" might be more appropriate. Practical living includes compromises regularly. Reference imaging is a choice, and a goal, that necessitates following certain imaging industry standards, engineering guidelines, and recommended practices. These elements enter into the conversation more in this calibration section of the AV Science Forum than others. Most video consumers simply have conflicting priorities and interests that are much more casual, or even disinterested, toward the pursuit of reference imaging. Excellence is sacrificed for the sake of convenience, limited budget, and/or due to indifference.
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post #11 of 15 Old 10-04-2013, 02:37 PM
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Hum.. maybe I sit way to far away (3 x screen height} from 110" screen, but paying a DVD in a BRP and projecting it with a PD8150 does not look "BAD" at my house. It is not 1080p24 from a BR disk, but it is very watchable and looks rather amazing considering it is STD. Watching the SD channels from the HD Set top box, now that is a different story all together...

Doug

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post #12 of 15 Old 10-04-2013, 03:18 PM
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Quote:
Originally Posted by airscapes View Post

Hum.. maybe I sit way to far away (3 x screen height} from 110" screen, but paying a DVD in a BRP and projecting it with a PD8150 does not look "BAD" at my house. It is not 1080p24 from a BR disk, but it is very watchable and looks rather amazing considering it is STD. Watching the SD channels from the HD Set top box, now that is a different story all together...
Why do you say "too far away?" Three screen heights is the typical recommendation for 1920 x 1080 since the early days of HDTV system design research in Japan. Both the SMPTE and ITU publications still discuss that as being the best general recommendation for critical viewing distance of HDTV images. SD programming on either satellite or cable set top boxes is the other extreme end of the quality scale, unless you still watch VHS tape.
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post #13 of 15 Old 10-04-2013, 03:31 PM
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Quote:
Originally Posted by airscapes View Post

Hum.. maybe I sit way to far away (3 x screen height} from 110" screen, but paying a DVD in a BRP and projecting it with a PD8150 does not look "BAD" at my house. It is not 1080p24 from a BR disk, but it is very watchable and looks rather amazing considering it is STD. Watching the SD channels from the HD Set top box, now that is a different story all together...

You are right that SD channels are well below DVD quality, in the same sense HD channels aren't close to BD quality. Lower native resolutions/high levels of compression are probably the reason TV channels don't compare well to optical disc formats. Netflix streaming (1080 Super HD quality) is in my experience much closer to BD than HD channels, provided your internet connection is fast and stable enough to support this level of quality during the whole video playback.


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post #14 of 15 Old 10-05-2013, 04:42 PM
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HD upconverted to UHD actually looks a little better if the upconversion includes anti-aliasing which most seem to do.

Say you have a diagonal line... aliasing is the stairstepping you inevitably get when you display the diagonal line on a video display with (square) pixels.

You may not be aware of aliasing in your HD images, but it IS there. When you go to UHD you have the opportunity to fill-in the big stairsteps with single pixels that smooth the diagonal line much more than is possible on an HD display. You also have an opportunity to remove the "sharp" pixel at the corner of a stairstep to make that step less coarse. So when you convert HD to UHD, you don't see more detail, per se, but the detail you do see is more distinct and "smoother" along all edges except perfectly vertical or perfectly horizontal edges. The most improvement would appear on 45 degree diagonals, but round objects are improved also, except at the 9-12-3-6 o'clock positions there that single pixel will look about the same on HD and UHD displays.

The problem with SD is you are upconverting it WAY MORE than you upconvert SD to fit an HD screen. When you do beyond doubling the horizontal or vertical resolution, you get into having to interpolate (i.e. making an educated guess) at how you should allocate pixels to make the SD image better. That doesn't always work very well. In fact, SD edges are so blurry that the upconversion process is more difficult to do well. And even the best SD upconversion I've ever seen can't make SD look better on an HD display than it looked on a good SD display. The leap from 720x480 pixels to 1920x1080 is just too big and starts with too little "information". There's just 345,600 pixels in an SD image (1 green dot, 1 red dot, and 1 blue diot make up 1 pixel). While HD has a little more than 2 million pixels, pretty close to a 6x increase. You'd think the 6X increase from SD to HD wouldn't be much worse than the 4X increase in pixel count from HD to UHD. And to answer that, I'd say that converting HD to 6X more pixels would look WAY better than converting SD to HD with 6X more pixels because the SD pixel count is so small from the outset. When you get below a threshold, the intormation density in the original image is so low, that upconversion doesn't do anything to make the image look better. The only way to make the images look better is to get farther from the screen when the information density is as low as SD. On the other hand, HD images have way more information to begin with so upconverting them is not as problematic. FURTHER... to see all the resolution of UHD images, you have to sit around 4 to 5.5 feet from a 60" display to see it all. if you upconvert HD to UHD, you'd want to sit somewhere close to the same distance as if you were watching an HD display, say 7-8 feet from a 60" display (yes, I know a lot of people don't sit that close, but they aren't seeing all the available detail at farther distances, their choice).
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post #15 of 15 Old 10-05-2013, 08:29 PM
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Quote:
Originally Posted by Doug Blackburn View Post

HD upconverted to UHD actually looks a little better if the upconversion includes anti-aliasing which most seem to do.

Say you have a diagonal line... aliasing is the stairstepping you inevitably get when you display the diagonal line on a video display with (square) pixels.

You may not be aware of aliasing in your HD images, but it IS there. When you go to UHD you have the opportunity to fill-in the big stairsteps with single pixels that smooth the diagonal line much more than is possible on an HD display. You also have an opportunity to remove the "sharp" pixel at the corner of a stairstep to make that step less coarse. So when you convert HD to UHD, you don't see more detail, per se, but the detail you do see is more distinct and "smoother" along all edges except perfectly vertical or perfectly horizontal edges. The most improvement would appear on 45 degree diagonals, but round objects are improved also, except at the 9-12-3-6 o'clock positions there that single pixel will look about the same on HD and UHD displays.

The problem with SD is you are upconverting it WAY MORE than you upconvert SD to fit an HD screen. When you do beyond doubling the horizontal or vertical resolution, you get into having to interpolate (i.e. making an educated guess) at how you should allocate pixels to make the SD image better. That doesn't always work very well. In fact, SD edges are so blurry that the upconversion process is more difficult to do well. And even the best SD upconversion I've ever seen can't make SD look better on an HD display than it looked on a good SD display. The leap from 720x480 pixels to 1920x1080 is just too big and starts with too little "information". There's just 345,600 pixels in an SD image (1 green dot, 1 red dot, and 1 blue diot make up 1 pixel). While HD has a little more than 2 million pixels, pretty close to a 6x increase. You'd think the 6X increase from SD to HD wouldn't be much worse than the 4X increase in pixel count from HD to UHD. And to answer that, I'd say that converting HD to 6X more pixels would look WAY better than converting SD to HD with 6X more pixels because the SD pixel count is so small from the outset. When you get below a threshold, the intormation density in the original image is so low, that upconversion doesn't do anything to make the image look better. The only way to make the images look better is to get farther from the screen when the information density is as low as SD. On the other hand, HD images have way more information to begin with so upconverting them is not as problematic. FURTHER... to see all the resolution of UHD images, you have to sit around 4 to 5.5 feet from a 60" display to see it all. if you upconvert HD to UHD, you'd want to sit somewhere close to the same distance as if you were watching an HD display, say 7-8 feet from a 60" display (yes, I know a lot of people don't sit that close, but they aren't seeing all the available detail at farther distances, their choice).

interesting... thanks for the reply


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