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Author Topic: "Why 4K Matters" - it's 2X rather than 4X...  (Read 2029 times)
Pete Berry
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« on: August 26, 2013, 07:20:13 PM »
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...the resolution of a 1080HD image. Still huge, but 4X would, of course, require 32MP images for 4X the spatial resolution. A very interesting article.
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Ray
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« Reply #1 on: August 27, 2013, 04:54:45 AM »
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The 4K refers to the approximate horizontal resolution which is double that of standard HD, ie, 3840 x 2160 as opposed to 1920 x 1080. In other words, approximately 8 mp as opposed to 2 mp.
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Pete Berry
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« Reply #2 on: August 27, 2013, 11:47:59 AM »
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The 4K refers to the approximate horizontal resolution which is double that of standard HD, ie, 3840 x 2160 as opposed to 1920 x 1080. In other words, approximately 8 mp as opposed to 2 mp.

Yes, but not "...four times the resolution of your 1920x1080 HD TV" as Michael stated in the article, which would be unbelievably extraordinary.
« Last Edit: August 27, 2013, 11:53:01 AM by Pete Berry » Logged
Wayne Fox
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« Reply #3 on: August 27, 2013, 12:03:00 PM »
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I guess it depends on how you define 4x the resolution and in the case of pixel based devices such as sensors and displays, the total pixels are traditionally what is compared.

 4K tv has 8.2 million pixels vs full HD at a little over 2 million pixels.  Doubling the linear resolution of a device requires 4x the total pixels (or sensels in the case of a sensor).  Pretty much an industry term, most describing 4K tv use 4x the resolution somewhere in their description.
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BJL
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« Reply #4 on: August 27, 2013, 12:16:17 PM »
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I guess it depends on how you define 4x the resolution and in the case of pixel based devices such as sensors and displays, the total pixels are traditionally what is compared.
I would not go so far as to say "traditionally" for what is mostly a marketing-hype driven neologism of using "resolution" to refer to pixel count. And it is somewhat contradicted by the video industry's usage of linear measures of resolution, like "1080" or "1920" or ... "4K"! I wish that were commonly done with still cameras, like "6K" or "6K x 4K" instead of "24MP".

How about we avoid ambiguity by saying "four times the pixel count" when that is what we mean, and leave "resolution" to refer to a linear measurement as it always has, at least to technically literate people, even when referring to digital capture and display devices. Or to avoid any ambiguity, "twice the linear resolution".
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RFPhotography
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« Reply #5 on: August 27, 2013, 12:32:25 PM »
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I guess it depends on how you define 4x the resolution and in the case of pixel based devices such as sensors and displays, the total pixels are traditionally what is compared.

 4K tv has 8.2 million pixels vs full HD at a little over 2 million pixels.  Doubling the linear resolution of a device requires 4x the total pixels (or sensels in the case of a sensor).  Pretty much an industry term, most describing 4K tv use 4x the resolution somewhere in their description.

Marketing bafflegarb doesn't make it right.  4X the pixels is 2X the resolution.  There's no way around the math.  Thing is, the people the TVs are being marketed to mostly won't know, so the marketers can get away with the lie.
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hjulenissen
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« Reply #6 on: August 28, 2013, 05:20:45 AM »
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Why does it matter? Some think vertically, some horizontally, some area. PR-people tend to think in whatever domain returns the biggest number (I do remember a Sony "Full-HD" tv bragging about 6.x million pixels, presumably that is counting the r-g-b triplets. Camera EVF/LCDs seems to do the same thing)

It is what it is:
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BartvanderWolf
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« Reply #7 on: August 28, 2013, 05:25:48 AM »
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I guess it depends on how you define 4x the resolution and in the case of pixel based devices such as sensors and displays, the total pixels are traditionally what is compared.

Hi Wayne,

I disagree. Resolution is measured as a dimension per unit length, i.e. width or height.
The total pixels metric is a quantity, not a dimension, thus no resolution can be derived without additional (width/height) information.

Cheers,
Bart
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RFPhotography
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« Reply #8 on: August 28, 2013, 06:07:10 AM »
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Why does it matter? Some think vertically, some horizontally, some area. PR-people tend to think in whatever domain returns the biggest number (I do remember a Sony "Full-HD" tv bragging about 6.x million pixels, presumably that is counting the r-g-b triplets. Camera EVF/LCDs seems to do the same thing)

It is what it is:


Ah yes, the Sigma trick. Grin  It matters because I believe truth in advertising matters.
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ErikKaffehr
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« Reply #9 on: August 28, 2013, 06:21:11 AM »
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Hi,

I project slide shows from digital images on a 1.7 m wide screen at about 2.5 m viewing distance. It is on the edge to acceptable quality with 1080P. With 4K i could have a wider screen and sit closer.

I am looking forward to 4K.

Best regards
Erik


...the resolution of a 1080HD image. Still huge, but 4X would, of course, require 32MP images for 4X the spatial resolution. A very interesting article.
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Wayne Fox
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« Reply #10 on: August 28, 2013, 12:42:39 PM »
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Well, despite the disagreements I think there is plenty of logic to 4x the resolution.   If I have 30" screens, one current high def and one 4K, the 4k has 4 times as many pixels to display the information.  That's how sensors have been marketed and described.  Yes, we all know that linear resolution is what really counts, and we all know that it takes 4x the pixels to double that.

But I have no problem with someone stating that a 4K TV has 4x the resolution of HD.

It's all marketing speak, and certainly those marketing are going to color it in the best way possible.  Can't blame them ...
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bcooter
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« Reply #11 on: August 28, 2013, 01:53:49 PM »
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Well, despite the disagreements I think there is plenty of logic to 4x the resolution.   If I have 30" screens, one current high def and one 4K, the 4k has 4 times as many pixels to display the information.  That's how sensors have been marketed and described.  Yes, we all know that linear resolution is what really counts, and we all know that it takes 4x the pixels to double that.

But I have no problem with someone stating that a 4K TV has 4x the resolution of HD.

It's all marketing speak, and certainly those marketing are going to color it in the best way possible.  Can't blame them ...

One thing I've noticed through the years is people do what they want.  If they think they see a difference in a 80mpx back they do, if they think they see a difference in 2k to 4k video . . . they do and they will use the cameras they like, want, can afford, or whatever.

I've shot a truck load of 4k, tons of 2k, usually side by side and went with 4k REDS, not for the sheer resolution, but because of the raw workflow, a 444 file, 12 to 14 stops of dr.  The R1's make a great file and give you a lot of room to work and even when edited in 2k I see a difference, but mostly due the professional nature of the file.

In regards to viewing 4k, I don't care.  I've seen a lot of 4k projected in every form of media and I don't see enough difference to care.

What I do see with 4k is your storage, processing power from computers, graphic cards goes up in kind.  There is no free lunch.

Red's next camera will be 8k and honestly at this point I see that more as a marketing trick rather than anything anyone really needs.

Personally, I view 90% of my entertainment from an Ipad, or computer screen, always download the SD versions for drive space, speed to download and costs.   If the production is professional, the editing and coloration expert, I notice that a lot more than I notice 2k, 4k, etc.

I'm not alone in the ipad world of viewing.   It's probably not socially acceptable, but I find so many people viewing streaming video on their own devices even in the same room.   I can hear my wife in her office listening to one program, I'm downstairs in another office working and watching something else, so if it really is a streaming world I don't think you'll see 4k anytime soon.

In regards to the Blackmagic camera, I wish them well, though know the original black magic had some issues, especially with noise at anything above base iso.  The 4k may be better (I hope so) and may be a game changer due to price, though price in motion imagery is all over the place.

Saving 10 grand on a body is a drop in the bucket compared to evfs, monitors on board and off, ssd cards, storage, computers, graphic cards, breakout boxes,  mounting rigs, supports . . . well you get the idea.  When cinema lenses average about 8 grand a lens, the actual digital brain is not the highest price item in the room.

IMO

BC
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BJL
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« Reply #12 on: August 28, 2013, 02:01:09 PM »
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Seriously Wayne, how hard is it to say "four times the pixels", and avoid any ambiguity?

And I will say it again, in partial contradiction to your comment that "That's how sensors have been marketed and described", the way that _video_ sensors, displays, and formats are marketing does NOT generally use pixel counts, it mostly uses linear measures like "1080p" and "4K". If TV buyers and movie-goers can handle measures like "4K", it should easy enough for us still photographers!
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mac_paolo
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« Reply #13 on: August 28, 2013, 05:13:13 PM »
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Oh well, so now the D7100 has twice the resolution of my old D40 because, sure, 6000 is 2x 3000. Ouch!!

No matter how people tend to perceive the terms, standards use the "Q" letter to express quarter/quadruple when a single dimension (which is NOT the resolution) is halved/doubled. Remember QVGA vs VGA?
Many people confuse pixel density (which effectively doubles from 1080p to 4K by retaining the same panel size) with resolution.

That "x" is not a marketing cliché, it really means it's a multiplication. It's way easier to remember two something-thousand factors than a single something-million number, but the latter is the resolution, whether you like it or not.

So…

* No need to invent new terms when the ones we have are just right.
* Michael is right.
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Pete Berry
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« Reply #14 on: September 07, 2013, 12:20:55 PM »
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"....Many people confuse pixel density (which effectively doubles from 1080p to 4K by retaining the same panel size) with resolution.

That "x" is not a marketing cliché, it really means it's a multiplication. It's way easier to remember two something-thousand factors than a single something-million number, but the latter is the resolution, whether you like it or not.

So…

* No need to invent new terms when the ones we have are just right.
* Michael is right."
mac_polo


Mac, I believe it's you who are confused! Increase the linear dimensions X2, which is what 4K does over 2K 1080 HD, and you have 4X the pixel density (pixels per unit area of same size sensor): 2x1=2, 4x2=8 = 4x(2x1). Resolution is a linear measurement only, expressed as lines/mm, inch, picture height, etc: when you double the pixel linear dimensions you double the sensor resolution, period. Draw any straight line through it - eg a diagonal, and it still intersects only twice as many pixels.

As Michael obviously knows this, my only conclusion is that he was either a bit addled by a sundowner or two too many when early on in the article he stated "...four times the resolution..." , or more likely he just threw it out as a teaser, a come-on to draw us into the article. Definitely got my attention to the end!

Pete

« Last Edit: September 07, 2013, 02:08:21 PM by Pete Berry » Logged
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