How is 4K Ultra HD "Four Times the Resolution" of 1080p? - Page 2 - AVS Forum
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post #31 of 49 Old 01-15-2014, 10:09 AM
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"When I use a word," Humpty Dumpty said, in rather a scornful tone, "it means just what I choose it to mean—neither more nor less."
"The question is," said Alice, "whether you can make words mean so many different things."
"The question is," said Humpty Dumpty, "which is to be master—that's all."
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post #32 of 49 Old 01-16-2014, 11:57 AM
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Quote:
Originally Posted by tgm1024 View Post

It is the chief complaint of Passive 3D.  Every other scanline is sent to one eye, the remaining scanlines to the other.  They alternate with Left/Right information all the way down the display.  Google 1920x540 or passive 3d half resolution.

You need to stop fighting this.

It takes 2 to tango.

I'm not questing the math. I think that's where you're confused. I'm questioning the perception. I don't think there's a 1 to 1 relationship between actual resolution and perceived resolution. I don't think most people will view UHD as being 4x as sharp as regular HD. That's what the marketers want to convey by calling it 4K instead of 2K. You seem to think it's a proven fact people will view it as being 4x as sharp as HD. I never thought DVD was 4x as sharp as HD even though HD has about 4x as many pixels.
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post #33 of 49 Old 01-16-2014, 12:01 PM
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Originally Posted by KidHorn View Post
 
Quote:
Originally Posted by tgm1024 View Post

It is the chief complaint of Passive 3D.  Every other scanline is sent to one eye, the remaining scanlines to the other.  They alternate with Left/Right information all the way down the display.  Google 1920x540 or passive 3d half resolution.

You need to stop fighting this.

It takes 2 to tango.

I'm not questing the math. I think that's where you're confused. I'm questioning the perception. I don't think there's a 1 to 1 relationship between actual resolution and perceived resolution. I don't think most people will view UHD as being 4x as sharp as regular HD. That's what the marketers want to convey by calling it 4K instead of 2K. You seem to think it's a proven fact people will view it as being 4x as sharp as HD. I never thought DVD was 4x as sharp as HD even though HD has about 4x as many pixels.

 

Regardless of what you would like to call it, "sharper" or whatever, the person is receiving 4 times the amount of image information in UHD than they are in HD, assuming all compression/subsampling issues are the same.

 

Believe what you like.  I have no more time for your line of reasoning.


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post #34 of 49 Old 01-16-2014, 12:16 PM
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Quote:
Originally Posted by tgm1024 View Post

NO. 4K comes from the HORIZONTAL pixel measurement.  In the film industry 4K was traditionally 4096.  However, to make it an even multiple of 1920, they used 3840 and used the 4K label to describe it.  There are some in the industry mildly upset about this as well, because it complicates how they describe the industry (movie) cameras (often 4096 wide) used to shoot this stuff.

What seems to be confusing you (and many others) is that they switched from 1080 (a vertical measurement) to 4K (a horizontal measurement).  And yes, this whole thing is profoundly annoying.

When you see 1080, think "2K" (and vice-versa) because 1080 in the 16:9 case is 1920 wide.  So "full" HD = "1080" = "2K".  A little nutty at first, PARTICULARLY because 1080 looks like 1/4th of 4096.  But they're differing dimension axes entirely.

So the following are synonyms you can use conversationally:

 



"Full HD" = "1080" (which is vertical) = "2K" (which is horizontal but measures 1920x1080 for a 16:9 screen)



"UHD" = "2160" (which is vertical) = "4K" (which is horizontal and measures 3840x2160 for a 16:9 screen)



 



Note: "Full HD" is usually called merely "HD", though that is technically incorrect because "HD" was originally 720 vertical.  ......which was also in current implementations is 768 vertical.....but try to ignore that because it's confusing as hell.  (LOL!)  Get the sense that this industry can't help but shoot itself in the ass?




Note: this has nothing to do with KidHorn's misunderstandings.

What misunderstanding?
What specifically about your above post have I failed to understand?

By the way, 768 vertical was never a HD standard. Although many TVs had a native resolution of it.
http://www.hdtvfaq.org/hdtv-formats.html#720p-on-a-1366-x-768-display
Assuming you think hdtvfaq.org is an acceptable authority. Unlike Wikipedia apparently.

It used to be very common for HDTVs to handle 1080 or 720 input, but display in a native resolution that wasn't either. I have an older TV that shows 900 lines of vertical resolution.

HD has always and still uses 720 and 1080 as a standard. At least since the 1990's when it had any practical use.
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post #35 of 49 Old 01-16-2014, 12:40 PM
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Quote:
 
Quote:
Originally Posted by KidHorn View Post

Quote:
Originally Posted by tgm1024 View Post

Note: "Full HD" is usually called merely "HD", though that is technically incorrect because "HD" was originally 720 vertical.  ......which was also in current implementations is 768 vertical.....but try to ignore that because it's confusing as hell.  (LOL!)  Get the sense that this industry can't help but shoot itself in the ass?

 

By the way, 768 vertical was never a HD standard. Although many TVs had a native resolution of it.
http://www.hdtvfaq.org/hdtv-formats.html#720p-on-a-1366-x-768-display
Assuming you think hdtvfaq.org is an acceptable authority. Unlike Wikipedia apparently.

It used to be very common for HDTVs to handle 1080 or 720 input, but display in a native resolution that wasn't either. I have an older TV that shows 900 lines of vertical resolution.

HD has always and still uses 720 and 1080 as a standard. At least since the 1990's when it had any practical use.

 

What on earth is all this now?  I didn't say 768 was the HD standard.  I said implementations.  An implementation is how something appears in real life, not a specification nor standard, but how the product is actually made.  And a number of "720p" sets are 768 vertical.


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post #36 of 49 Old 05-23-2014, 12:35 PM
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The UHD display industry hijacked the graphic arts term "resolution" and turned it from a linear measurement (pixels per inch) into an area measurement (pixels wide x pixels high = pixels square). 

 

You see, I come from a graphic arts background where a 300 PPI image is twice the "resolution" of a 150 PPI image, and four times the resolution of 72 PPI. PPI = pixels per inch. It is a one-dimensional metric (horizontal or vertical). In this context, we are talking about a pixel that is square (1:1 ratio of width to height). Of course, non-square pixels used in some imaging technologies do complicate the matter. 

 

"PPI" as a measure of "image resolution" or "input resolution" is similar to the concept of DPI – dots per inch – which is a linear or pitch measure of the "imaging resolution" or "output resolution" of traditional imagesetters (outputting halftone dots on negative film) and current printing devices using stochastic screening. A rule of thumb for good print quality has always been to have 1.5 to 2 times the PPI (image resolution) as DPI (print device resolution).

 

I take offense to the claim that "4K is four times the resolution of 1080p." The UHD industry really needs to say:

 

"4K is four times the total number of pixels as 1080p." – here we are comparing total area – pixels wide times pixels high

 

or:

 

"4K is two times the pixel dimensions of 1080p." – here we are comparing the number of pixels wide and the number of pixels high

 

Note that "1080p" is the number of pixels high. "4K" is the number of pixels wide. So don't make the mistake of saying "4K (4000 pixels) is four times the resolution of 1080p" based on those numbers. 

 

As far as comparing "resolution" in the graphic arts industry, let's take the case of a 10" x 10" 300 PPI Photoshop image vs. a 10" x 10" 72 PPI image.

 

10 inches x 10 inches @ 300 PPI = 9,000,000 pixels square (area)

10 inches x 10 inches @ 72 PPI = 518,400 pixels square (area)

9,000,000 / 518,400 = 17

 

The 300 PPI image would actually be 17 times larger as far as the total number of square pixels in the image.

 

No one in the graphic arts industry would ever say "a 300 PPI scan is 17 times the resolution of a 72 PPI scan." No, they would say "a 300 PPI scan is 4 times the resolution of a 72 PPI scan." This would be a linear measure, in one dimension only, of pixels per inch. 

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post #37 of 49 Old 05-23-2014, 01:56 PM
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Quote:
Originally Posted by rschletty View Post

I take offense to the claim that "4K is four times the resolution of 1080p." The UHD industry really needs to say:

 

"4K is four times the total number of pixels as 1080p." – here we are comparing total area – pixels wide times pixels high

 

No.  "Resolution" technically is related to the ability to resolve.  Essentially how faithfully an image is represented; or your ability to resolve what it is.  It's actually more complicated than it seems....I have a 2x2 sensor explanation elsewhere.

 

And despite how it came to be used within the printing/computer graphics industry as a linear measurement of pixel density, it is not DPI with displays.  Though through common usage it is often used that way now in printing/graphics, so you can use it if you like, but you'll end up with issues here with displays.  You'll see quite a few of us in these parts be careful to use PPI.

 

Imagine a 100x100 display next to a 200x100 display.  The 200x100 display has precisely twice the number of pixels, twice the amount of visual information, and therefore twice the resolution.

 

You have four times the visual information with UHD than you do with full HD.  It is absolutely correct to say that UHD is four times the resolution of full HD.  It is incorrect to say that UHD is twice the resolution of full HD.

 

Your (printing) usage of resolution == dpi does not take into account x and y linear resolutions that differ.  You would have no way of explaining what the DPI is of the above monitor in a single number.

 

We go through this over and over and over.


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post #38 of 49 Old 05-23-2014, 03:40 PM
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Maybe we need to describe the resolution of video cameras and monitors as PPW or PPH. 

 

PPW = pixels per screen width

PPH = pixels per screen height

 

Oh wait, we already have a term for that – pixel dimensions. See Photoshop's "Image Size" dialog.

 

Perceptually, a 4K film frame is only twice as "detailed" as a 1080p film frame because it only has twice the number of pixels in width or twice the number of pixels in height.

 

I have 22 years of experience as a Photoshop artist, print designer and prepress consultant. And 10 years as a web designer. I am now shooting with a Blackmagic Production Camera 4K and a GoPro Hero 3+ at 2.7K and 4K. I am editing footage with Adobe Premiere Pro and full DaVinci Resolve. 

 

Cut me some slack. I have a certain way of defining "resolution" that seems to go against the way they are marketing 4K over 1080p. 

 

How would you compare the "resolution" of 4K vs. 2.7K? 1.4X the resolution (comparing horizontal dimensions) or 2X the resolution (comparing total number of pixels)? 

 

2.7K = 2704 px wide x 1524 px high = total of 4,120,896 pixels

4K = 3840 px wide x 2160 px high = total of 8,294,400 pixels

 

Never mind the aspect ratio – whether it is 4:3 or 16:9 or 17:9. What is the perceptual difference? 

 

If I had a box that was "4X as big" as another box, would you visualize a box that is 4X as large in ALL dimensions (64 times the volume)? Or 4X as large in just one dimension (4 times the volume)? 

 

If I asked you, "How big is the Pacific Ocean?" you would probably ask me whether I want to know its width, surface area or volume. 

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post #39 of 49 Old 05-23-2014, 06:32 PM
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As a graphics/imaging software engineer, I spent a very long time conversationally treating resolution as DPI in precisely the same way you do.  Most of the time it's ok.  And in the cases where the pixels were non-square we'd deal with two linear resolutions.  That's how computer graphics and imaging (and prepress) delt with things, and I've written many algorithms using two linear resolutions.

 

But when you get to the point where you say things like:

Quote:
Originally Posted by rschletty View Post

I take offense to the claim that "4K is four times the resolution of 1080p."

 

...you need to accept that perhaps you're missing something.  That twice each linear dimension yielding four times the information is four times the resolution.  Taking "offense"?  This means that you don't understand the concept behind image information.

 

Leaving blur, anti-aliasing, duplicated pixels, etc., etc., etc., out of the equation, and given displays of equal physical dimensions:

  • Twice the image data (from 100x100 to 200x100) yields twice the visual information.  And twice the ability to visually resolve the image.  You then have effectively twice the clarity.  It is twice the resolution.
  • Four times the image data (from 100x100 to 400x100, or from 100x100 to 200x200) both yield four times the visual information.  Four times the ability to resolve the image.  Four times the resolution.

 

Wave your fist into the air and "take offense" all you like, but it's what the notions mean, so your battle will be uphill and pointless.  The display industry absolutely has it right.


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post #40 of 49 Old 05-25-2014, 09:24 AM
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You might want to use 142x142 (sqrt 20000) as an example instead of 100x200, just to keep things more clear.
I think the "problem" of perception lies in the fact that we're so used to 4x pixel count increases.

No one is going to replace original 128x128 game textures with 181x181 versions. It's going to be 256x256 instead. I think might have learned to associate 4x increase as something that's twice as clear.
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post #41 of 49 Old 05-25-2014, 10:18 AM
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You might want to use 142x142 (sqrt 20000) as an example instead of 100x200

 

No, I specifically needed to bring an example that was of differing linear resolutions to drive the point home of what "resolution" means.  "Resolution" is derived from more than just one linear metric when it comes to displays.


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post #42 of 49 Old 05-25-2014, 03:44 PM
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Shouldn't they measure the resolution you will be getting on the TV for different content to give you a more accurate/representative idea of the 'resolution' of the display (when displaying actual/average, available video - and not just static charts), and for the increase in 'resolution' of the display compared to full HD displays?

ie. take into account motion, blurring, frame rates, shutter settings, content quality (which would depend on lens, sensors, compression, motion, etc. - different scenes/parts of scenes will have a higher resolution) and not just number of pixels in the display. Just saying the number of pixels in the display isn't telling the whole story, especially for a TV which is for moving video. Just saying pixel count/increase isn't telling you the increase in 'resolution' you will actually be getting.
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post #43 of 49 Old 05-25-2014, 04:15 PM
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Shouldn't they measure the resolution you will be getting on the TV for different content to give you a more accurate/representative idea of the 'resolution' of the display (when displaying actual/average, available video - and not just static charts), and for the increase in 'resolution' of the display compared to full HD displays?

ie. take into account motion, blurring, frame rates, shutter settings, content quality (which would depend on lens, sensors, compression, motion, etc. - different scenes/parts of scenes will have a higher resolution) and not just number of pixels in the display. Just saying the number of pixels in the display isn't telling the whole story, especially for a TV which is for moving video. Just saying pixel count/increase isn't telling you the increase in 'resolution' you will actually be getting.

 

You'd then have to issue a complete set of metrics for every frame of every TV show and movie ever watched on the thing.


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post #44 of 49 Old 05-25-2014, 04:29 PM
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Quote:
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You'd then have to issue a complete set of metrics for every frame of every TV show and movie ever watched on the thing.
No, just a representative sample.

eg.
Actual achievable 'resolution' when watching:
* Blu-ray 1080p24 content (show an average resolution figure based on the 10 (or more if they want it to be more accurate) most popular titles, based on the average for each of those titles or a representative section of each title (eg. 10 min of each).
* Freeview HD channels
* Freeview UHD 2160p50 content
* Freeview UHD 2160p100 or 150 content
* Blu-ray 4K 24 fps content
* Blu-ray 4K 100/120 fps content
- so the above is just showing a resolution figure (average) for each of those source types. eg. an average resolution (eg. horizontal and vertical amount of detail which can be resolved on average when watching those sources - not static)

Or just show figures from the main video content (not static content) that can achieve the highest 'resolution' figures for the TV (without motion interpolation).
eg. "Achievable Resolution: ... * when watching Blu-ray UHD 120 fps".

edit: there could also be something a bit like in the BDInfo stats where it shows a graph of the bitrates, but instead it would be a graph of typical/average resolutions for a particular length of time. eg. for the video (not static) sources with the highest available resolutions.
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post #45 of 49 Old 05-27-2014, 09:24 AM
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I agree with tgm. In TV parlance, resolution is directly related to the number of pixels. It's the same with camera's. A 10 mb camera is considered twice the resolution of a 5 mb. In this case, the mb number is the number of pixels.

Whether or not this is misleading is up to each person, but the term resolution has been used this way consistently over the years for TVs and cameras.
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post #46 of 49 Old 05-27-2014, 10:41 AM
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In print you would definitely refer to dots-per-inch (DPI) and not use any other method to judge resolution.
TV and camera manufacturers would of course love it if you refer to 2x the density as 4x the resolution. It's in their favor to do so.

I agree that density (pixels-per-inch) is what actually matters as far as actual resolution is concerned - though I'm not too pleased with the per inch measurement, and would rather see something using metric.
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post #47 of 49 Old 05-27-2014, 04:50 PM
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Even in print, my rendering algorithms had to take into account two linear resolutions.

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post #48 of 49 Old 05-28-2014, 12:26 AM
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Quote:
Originally Posted by tgm1024 View Post

Even in print, my rendering algorithms had to take into account two linear resolutions.
A 300 DPI print is still considered to be twice the resolution of a 150 DPI print though, not four times the resolution.
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post #49 of 49 Old 05-28-2014, 07:19 AM
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Quote:
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Quote:
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Even in print, my rendering algorithms had to take into account two linear resolutions.
A 300 DPI print is still considered to be twice the resolution of a 150 DPI print though, not four times the resolution.

 

Sure.....and that's how we casually referred to it as well, and at the application level it is often errantly presented as a single number.  But algorithmically, that number is only valid right up until that printer is actually (say) 400 dpi horizontally and 300 dpi vertically at the lowest level.  I had to deal with this kind of thing back in the day.  If you wrote a renderer that took into account only square pixels, you were in for trouble eventually.

 

But none of this relates to the display industry usage anyway, and railing against their usage of resolution borders on pedantry, especially since they actually have it right.


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