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"2K" does not mean 2560×1440

Glenwing
10 hours ago, beakhole said:

The title to this post is silly. Anyone who says that is silly. 2K means 2560x1440, sorry guys. It means 2k in the same way that the word "D'oh" ended up appearing in dictionaries with an official meaning after the Simpson's had been playing for 10 years - it is the meaning we've assigned to it as silly humans and that's just the way it is. People bothered by 2k referring to 2560x1440 have OCD or are trying to prove that they know stuff about computers that you don't know - either way they are the silliest of the sillies. 

Yeah... One centimeter means 13 mm. Not 10. So anyone telling you 1 cm = 10 mm are just trying to prove they know more physics than you. Also, the Earth is flat and vaccines cause autism and can only be cured by drinking colloidal silver water.

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  • 7 months later...

I know this thread is a bit old but I have been having this discussion with other people recently and for the benefit of the OP in the usage in Cinematography section - if RED, Canon and Blackmagic aren't enough for some reason:

 

Arri

http://www.arri.com/camera/alexa/tools/arri_formats_datarate_calculator/

 

(just pick ALEXA 65 or AMIRA and see the resolutions - moreover it's clear as day that they use "K" as an approximation since you have 2.2k, 2.8k, 3.2k etc.)

 

Sony

https://pro.sony/ue_US/products/shoulder-camcorders/pxw-z450#ProductSpecificationsBlock-pxw-z450 

 

Sony’s ground-breaking PXW-Z450 combines 4K resolution (3840 x 2160) with superbly balanced shoulder-mount ergonomics and a versatile 2/3-inch B4 lens mount. It’s a robust, high performance acquisition tool for 4K and HD news, documentaries, live events and general field production.

The PXW-Z450 records 4K QFHD (3840x2160) at 50p/59.94p

 

If RED, Arri, Sony, Canon and Blackmagic aren't enough then nothing is enough ;-)

 

 

 

 

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1 hour ago, Lathlaer said:

I know this thread is a bit old but I have been having this discussion with other people recently and for the benefit of the OP in the usage in Cinematography section - if RED, Canon and Blackmagic aren't enough for some reason:

 

Arri

http://www.arri.com/camera/alexa/tools/arri_formats_datarate_calculator/

 

(just pick ALEXA 65 or AMIRA and see the resolutions - moreover it's clear as day that they use "K" as an approximation since you have 2.2k, 2.8k, 3.2k etc.)

 

Sony

https://pro.sony/ue_US/products/shoulder-camcorders/pxw-z450#ProductSpecificationsBlock-pxw-z450 

 

Sony’s ground-breaking PXW-Z450 combines 4K resolution (3840 x 2160) with superbly balanced shoulder-mount ergonomics and a versatile 2/3-inch B4 lens mount. It’s a robust, high performance acquisition tool for 4K and HD news, documentaries, live events and general field production.

The PXW-Z450 records 4K QFHD (3840x2160) at 50p/59.94p

 

If RED, Arri, Sony, Canon and Blackmagic aren't enough then nothing is enough ;-)

What exactly is the point your'e trying to make?

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21 minutes ago, Ryan_Vickers said:

What exactly is the point your'e trying to make?

The same point @Glenwing made when he wrote the original post. Under the section of usage of "k" in cinematography he gave specific examples of RED, Canon and Blackmagic Design.

 

I just thought that for more impact Arri and Sony could be added as some of the leading companies in the cinematography industry.

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  • 4 weeks later...

Finally somebody explained this.

 

I was annoyed by people referring 16:9 1440p as 2K. 2K means ~2000 pixels.

This could be DCi (2048) or ordinary (1920). It was originally meant for DCi, but can be used interchangeably. But 1440p 16:9 is certainly 2,5K due to 2560 pixels of width (in rare occasions 2592 pixels).

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I've even seen a 3440 x 1440 monitor referred to as "2K" now, proving they really have absolutely no idea what it means and are just using it as a drop in replacement for 1440p

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  • 4 months later...

You know what would be less confusing to everyone that probably would be easier at this point that so many use it wrong?

 

Just make everyone stop using 2k and make them only say 1080 or 1440p instead.

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On 11/16/2016 at 10:23 AM, EminentSun said:

The whole 4k thing is kind of ridiculous. We should just be calling it 2160p, but nooooooo. Some marketing team decided to introduce a ridiculous moniker.

Yeah it is ridiculous but it takes longer to type 2160p i say 4k because everyone knows what it is same goes for 2k, fuck calling it the longest thing possible if you're going to do that may as well say 3840x2160p and 4096x2160p who would want to do that? if you're buying something the specs are on the box.

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14 hours ago, Wormhole said:

Yeah it is ridiculous but it takes longer to type 2160p i say 4k because everyone knows what it is same goes for 2k, fuck calling it the longest thing possible if you're going to do that may as well say 3840x2160p and 4096x2160p who would want to do that? if you're buying something the specs are on the box.

Well the problem is actually that a lot of people don't know what 4K or 2K means, hence this thread :P

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  • 1 year later...

As a tangential topic to this, is there any point in having the 'p' in the resolutions that refer to the vertical? Unless you're working in news/entertainment broadcast TV, you're never going to be using an interlaced signal and surely all consumer displays are progressive scan these days so the 'p', while accurate, is arguably irrelevant I'd say.

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1 hour ago, W.D. Stevens said:

As a tangential topic to this, is there any point in having the 'p' in the resolutions that refer to the vertical? Unless you're working in news/entertainment broadcast TV, you're never going to be using an interlaced signal and surely all consumer displays are progressive scan these days so the 'p', while accurate, is arguably irrelevant I'd say.

Very true, but something like "1080p" is instantly recognizable as a resolution since (at least as far as what's coming to mind at the moment) nothing else is really stated that way.  The number "1080" alone on its own like that however is far less clear.  Plus, it's not really so much effort to add it.

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  • 1 year later...

Thank you for this thread, I'm glad there are others who realize how stupid this 4K and 2K shit is, and how people call 1440p 2K, but not 1080p...

hug?

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On 2/17/2019 at 12:55 AM, Mihle said:

You know what would be less confusing to everyone that probably would be easier at this point that so many use it wrong?

 

Just make everyone stop using 2k and make them only say 1080 or 1440p instead.

It's like the whole "2K21" instead of 2021 thing. It literally doesn't even save time to use these ridiculous abbreviations.

If someone did not use reason to reach their conclusion in the first place, you cannot use reason to convince them otherwise.

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7 hours ago, Hug said:

Thank you for this thread, I'm glad there are others who realize how stupid this 4K and 2K shit is, and how people call 1440p 2K, but not 1080p...

Thanks for bumping this!  I'm glad someone laid it out.  There's a lot of misinformation that keeps creeping back into discussions on display resolutions.

 

@vanished

 

the "P" is for progressive scan.  This was useful nomenclature when many displays were marketed as "1080 capable" but were only capable of 1080i (interlaced).  Since I don't anticipate progressive scan to be a discriminating factor much in the future (if at all)--I would like to see a letter added for aspect ratio.  That would make it very easy to compare displays at a glance.  This would also eliminate "ultrawide" and "super-ultrawide" from the lexicon--further easing confusion.

 

For example:

 

5:4 = "A"

4:3 = "B"

16:10 = "C"

16:9 = "D"

21:9 = "E"

32:9 = "F"

etc.

 

So a conventional 1080p panel could be called "1080D", whereas a WUXGA panel could be called "1200C"  A gaming monitor like the G9 could be called 1440F.

 

What do you think?

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3 hours ago, IPD said:

the "P" is for progressive scan.  This was useful nomenclature when many displays were marketed as "1080 capable" but were only capable of 1080i (interlaced).  Since I don't anticipate progressive scan to be a discriminating factor much in the future (if at all)--I would like to see a letter added for aspect ratio.  That would make it very easy to compare displays at a glance.  This would also eliminate "ultrawide" and "super-ultrawide" from the lexicon--further easing confusion.

 

For example:

 

5:4 = "A"

4:3 = "B"

16:10 = "C"

16:9 = "D"

21:9 = "E"

32:9 = "F"

etc.

 

So a conventional 1080p panel could be called "1080D", whereas a WUXGA panel could be called "1200C"  A gaming monitor like the G9 could be called 1440F.

 

What do you think?

I think letters won't solve a thing. You are just hiding the information in a similar label as "2k" or "4k" and will create similar confusion. The other reason why letters will be confusing is because e.g. "1200R" is used to indicate curvature, so how is one supposed to know if R indicates some weird 1200p aspect ratio or a 1200 mm radius of curvature.

 

If it's a 16:9 1080p display, simply label it as a 16:9 1080p display.

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6 minutes ago, tikker said:

I think letters won't solve a thing. You are just hiding the information in a similar label as "2k" or "4k" and will create similar confusion. The other reason why letters will be confusing is because e.g. "1200R" is used to indicate curvature, so how is one supposed to know if R indicates some weird 1200p aspect ratio or a 1200 mm radius of curvature.

 

If it's a 16:9 1080p display, simply label it as a 16:9 1080p display.

16:9 1080p 21:9 1080p etc

if 1440p is actually called 3k i'd have no problem, but i digress, whatever.

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1 hour ago, tikker said:

I think letters won't solve a thing. You are just hiding the information in a similar label as "2k" or "4k" and will create similar confusion. The other reason why letters will be confusing is because e.g. "1200R" is used to indicate curvature, so how is one supposed to know if R indicates some weird 1200p aspect ratio or a 1200 mm radius of curvature.

 

If it's a 16:9 1080p display, simply label it as a 16:9 1080p display.

 

I'm not sure how that's hiding any information.  It's using a letter-designator to identify something.  I'm also aware that r-value is used for identifying curvature.  I wasn't anticipating having enough aspect-ratio standards to justify letters that far in the alphabet.  In my mind, it's far simpler to say "1080D" than "1080p, 16:9"

 

To me, the ideal monitor spec would be like reading tire specs.

 

225/55r16 95H

 

This^ tells you the width, aspect ratio, wheel size, radial tire (not bias ply), load rating and speed rating--all at a glance.  Just like (for example):

 

1080D/144 R1500

 

Could tell you at a glance the resolution, refresh rate, aspect ratio and curvature.  No hiding information.  Everything is there in digestible format; and once you understand the nomenclature, it's very easy to differentiate products.

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15 minutes ago, IPD said:

I'm not sure how that's hiding any information.  It's using a letter-designator to identify something.

I guess obscuring is a better word than hiding. We already have the designations: 4:3, 16:9, 21:9. By saying A=4:3, B=16:9, C=21:9 you're merely adding another layer that needs translating.

15 minutes ago, IPD said:

1080D/144 R1500

 

Could tell you at a glance the resolution, refresh rate, aspect ratio and curvature.  No hiding information.  Everything is there in digestible format; and once you understand the nomenclature, it's very easy to differentiate products.

Yet another problem I'd see is the "p" suffix. 1080D would be confusing next to 1080p. A label "1080p 16:9" tells you the same in the same glance without the additional translation of "what aspect ratio did D indicate again?". The spec can simply read "16:9 1080p@144Hz" without such letters and all the information would be there and recognised as quickly, if not quicker. The less knowledgeable consumer would probably also confuse 1080D being better or worse than 1080A, just like an A-label fridge is more energy efficient than a D-label one.

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3 hours ago, IPD said:

Could tell you at a glance the resolution, refresh rate, aspect ratio and curvature.  No hiding information.  Everything is there in digestible format; and once you understand the nomenclature, it's very easy to differentiate products.

If you want notation that entirely describes a video format, how about:

 

1920 × 1080 (16:9)

 

Now that's digestable. There's no need to come up with a complicated code language for no reason.

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5 minutes ago, Glenwing said:

There's no need to come up with a complicated code language for no reason.

Absolutely.

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I'm guessing you never shop for tires either.  ^^

 

40V-2160D/60 R3000 - is my current 40" monitor, VA panel, 2160p resolution, 60hz refresh, and 3000r curve

 

15.6I-1620D/60 R0 - is the original IPS, 3k, 60hz panel on my 15" GT60 laptop

 

15.4T-1200C/60 R0 - is the TN, WUXGA, 60hz panel on my old 15" Sager 8662

 

22C-1440B/70 R0 - is my old NEC 22" 1920x1440, 70hz CRT from back in 2002

 

it's not complicated when you are taking specs that you'd have to find in 6+ locations and putting them all in one header.

 

 

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17 hours ago, tikker said:

I guess obscuring is a better word than hiding. We already have the designations: 4:3, 16:9, 21:9. By saying A=4:3, B=16:9, C=21:9 you're merely adding another layer that needs translating.

Yet another problem I'd see is the "p" suffix. 1080D would be confusing next to 1080p. A label "1080p 16:9" tells you the same in the same glance without the additional translation of "what aspect ratio did D indicate again?". The spec can simply read "16:9 1080p@144Hz" without such letters and all the information would be there and recognised as quickly, if not quicker. The less knowledgeable consumer would probably also confuse 1080D being better or worse than 1080A, just like an A-label fridge is more energy efficient than a D-label one.

I get what you're saying.  At the same time, "gauge" is inversely proportional when talking about wires/cabling (smaller gauge = larger wire).  On the other hand, with model railroads "gauge" is nomenclature that's all over the place with sizing.  That's just how some industries are.

 

My frustration is that there's no industry standards in display nomenclature.  The terms thrown around are so nebulous that we even have this thread to explain why "2k" does not --and should not--be used to signify 1440p.  Add onto that 32:9 and 21:9 displays being called "1080p" or "1440"--meaning no differentiation from 16:9 unless you dig down into the specs.  And then there's "UHD, QHD, and FHD--all of which technically apply to multiple resolutions--and you end up with even more confusion.

 

There are a lot of specs to cover, and the more succinctly you can cram that into one universal format--the better; even if there's a small learning curve to understand.  Ideally this then eliminates marketing chicanery that obfuscates product information.  My only wish is that ANSI would put its foot down and enforce something even if not my suggested method here.

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On 11/15/2016 at 6:18 PM, Glenwing said:

 

Terms like "2K" and "4K" don’t refer to specific resolutions. They are resolution categories. They are used to classify resolutions based on horizontal pixel count. "2K" refers to resolutions that have around 2,000 (2K) pixels horizontally. Examples include:

  • 1920 × 1080 (16:9)
  • 1920 × 1200 (16:10)
  • 2048 × 1080 (≈19:10)
  • 2048 × 1152 (16:9)
  • 2048 × 1536 (4:3)

All of these are examples of 2K resolutions. 1920×1080 is a 2K resolution. 2048×1080 is another 2K resolution. 2560×1440 is not a 2K resolution, it is a 2.5K resolution.

 

"2.5K" refers to resolutions around 2,500 (2.5K) pixels horizontally. For example:

  • 2304 × 1440 (16:10)
  • 2400 × 1350 (16:9)
  • 2560 × 1080 (64:27 / ≈21:9)
  • 2560 × 1440 (16:9)
  • 2560 × 1600 (16:10)

All of these are examples of 2.5K resolutions.

 

So why do people call 2560×1440 "2K"?

 

Because when "4K" was new to the consumer market, people would ask: "What's 4K?", and usually the response was "it’s four times as many pixels as 1080p". Unfortunately most people misinterpreted this and assumed that the "4" in "4K" actually stood for "how many times 1080p" the resolution was, and since 2560×1440 is popularly known as being "twice as many pixels as 1080p" (it's 1.77 times, but close enough), some people decided to start calling it "2K", and other people heard that and repeated it.

 

While it’s true that 4K UHD (3840×2160) is four times as many pixels as 1920×1080, that isn’t why it’s called "4K". It’s called 4K because it's approximately 4,000 pixels horizontally. The fact that it’s also 4 × 1080p is just a coincidence, and that pattern doesn’t continue with other resolutions.

 

For example, the 5K resolution featured in the Retina 5K iMac, 5120×2880, is equivalent to four 2560×1440 screens. If 1440p is "2K" because it’s twice as many pixels as 1080p, then wouldn’t four of them together be called "8K"? (Well, technically 7K since like I said 1440p is 1.77 times not 2 times 1080p, but that’s beside the point). We don’t call it 7K or 8K. We call it 5K, because it's around 5,000 pixels horizontally. It has nothing to do with "how many times 1080p" the resolution is.

 

In addition, an actual 8K resolution such as 8K UHD (7680×4320) is equivalent to four 4K UHD screens. A single 4K UHD screen is four times as many pixels as 1080p, so four of those together is sixteen times as many pixels as 1080p. But 7680×4320 isn't called "16K", it’s called "8K", because it’s approximately 8,000 pixels horizontally. Again it doesn't have anything to do with "how many times 1080p" the resolution is.

 

So although 2560×1440 is around twice as many pixels as 1080p, it is not called "2K", because that isn’t where these names come from. Since 2560×1440 is approximately 2,500 pixels horizontally, it falls into the 2.5K classification.

 

Examples of How the Cinematography Industry Uses These Terms

  Reveal hidden contents

RED:

  Reveal hidden contents

 

large.58364b40a1101_ss(2016-11-06at03_05

 

large.58364b416c8d7_ss(2016-11-06at03_06

 

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RED Scarlet-W Manual

 

In the charts above, the naming convention is made pretty clear, though it's not without its inconsistencies. For example, every 6:5 format has a far lower horizontal pixel count than its name suggests since these formats are intended to be used with anamorphic lenses, and the images will have a wider horizontal pixel count once they are de-squeezed. There are other minor oddities like 5568×3160 being classified as 6K while 5632×2948 is classified as 5.5K, but this is somewhat expected since this naming convention does not have any "official" set of rules for determining names, it's all just convention-based. In any case, despite the occasional deviation, the main pattern of the naming convention quite clearly follows the horizontal pixel count, and definitely not "how many times 1080p".

 

Just to sum up some of the more interesting parts of the above charts from the RED Scarlet-W manual:

  • 1920×1080 is listed as "2K 16:9 (HD)".
  • 2560×1080 is listed as "2.5K 2.4:1". Despite being an "ultrawide" version of 1920×1080 (2K 16:9), calling it "2K ultrawide" is improper usage of the term 2K, as it is a 2.5K resolution, not 2K.
  • 2560×1340 is listed as "2.5K Full Frame", it’s safe to say if 2560×1440 were included on the list it would be classified as a 2.5K resolution as well. (You might think ''1340" is just a typo for "1440", but actually it's more likely a typo for "1350", which would make it a 256:135 (≈19:10) ratio which is consistent with the other full frame resolutions listed)
  • 3840×2160 and 4096×2160 are both classified as 4K resolutions. 4096×2160 is not "the only" 4K resolution.
  • 5120×2160 (ultrawide version of 3840×2160) is listed as "5K 2.4:1". Calling it "4K ultrawide" is improper usage of the term 4K, as it is a 5K resolution, not 4K.

 

Blackmagic Design:

 

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Blackmagic Cinema Camera PL

2400×1350 is classified as a 2.5K resolution here. A slightly higher resolution like 2560×1440 would also be classified a 2.5K, certainly not 2K.
 
Canon:
 
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Note here that 2048×1080 and 1920×1080 both fall under the "2K" categories. 2K definitely does not refer to 2560×1440 or similar resolutions. 4096×2160 and 3840×2160 are also both classified as "4K" resolutions. 4096×2160 is not "the only" 4K resolution.

 

"True 4K"

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"True 4K"

 

While I’m here, I may as well address this one too. Some people will get upset when you call 3840×2160 "4K", and will say:

 

"3840×2160 isn’t ‘4K’, that’s ‘UHD’! True 4K is 4096×2160!"

 

And some go as far as saying 4K TVs are a consumer scam because they're not "real 4K". This is nonsense, really. As explained at the top, "4K" isn’t a resolution. It’s a category. The term is used to refer to any resolution approximately 4,000 (4K) pixels horizontally, for example:

  • 3840 × 1600 (24:10 / ≈21:9)
  • 3840 × 2160 (16:9)
  • 3840 × 2400 (16:10)
  • 4096 × 2160 (≈19:10)
  • 4096 × 2304 (16:9)
  • 4096 × 2560 (16:10)
  • 4096 × 3072 (4:3)

All of these are examples of 4K resolutions. None of them is "the one true" 4K resolution, because there is no such thing. They are all classified as 4K resolutions, and neither 3840×2160 nor 4096×2160 is more "true" than the other.

 

In digital cinema where these terms originate from, "4K" is and always has been a generic term that refers to a class of resolutions, not any one specific resolution. This idea that 4096×2160 is the "true 4K definition" used in cinema, you may notice, is only held by consumer-level internet people, not by anyone actually involved in cinema.

 

Yes, 4096×2160 is established as a standard resolution by the DCI specification, and they do refer to it as 4K, but that is not a term that they came up with, it's only a generic term. It's no more of a name for 4096×2160 than if you wrote a new standard saying "we're going to establish a standardized 16:9 resolution, 1600×900" and then you had a bunch of people running around on the internet saying "1600×900 is the true 16:9 resolution, it's defined in this standard, 1920×1080 isn't really 16:9!"

 

4096×2160 is not "the definition" of 4K, it is just one of several standardized 4K resolutions, just as we have several standardized 16:9 resolutions but none of them are "the definition" of 16:9, because 16:9 isn't a resolution, it's a category (in this case, anything with a width-to-height ratio of 16:9 fits in that category). And in both cases, it's not really about what resolutions are established by standards. If you have a resolution with a ratio of 16:9, then it's a 16:9 resolution, it doesn't have to have a standards document to go with it, and the same applies to 4K; any resolution with ≈4,000 horizontal pixels is a 4K resolution, because that's the definition of 4K.

 

The entire "4096×2160 is true 4K" thing was completely made up by tech news websites when 4K TVs were first starting to appear. Of course, all the major tech websites wanted to write a "4K explained" article, and of course being consumer-level writers, they themselves knew nothing about the established usage of the term "4K" (which had been used for years in cinema at this point).

 

Long story short, all the articles about "4K explained" were written by a bunch of consumers who know nothing about cinema, and are based on a few Google searches for "4K" in which these writers saw that 4096×2160 was mentioned a lot (since it is quite a common resolution), investigated a little and saw that it was a DCI standard, and leapt to the conclusion that "4K" was a unique name that referred exclusively to 4096×2160 in the same way that "Full HD" refers to 1920×1080.

 

Unfortunately their little assumption was completely wrong, and none of them researched enough to understand how the term "4K" was (is) actually used in industry. But boy did it catch on. Mostly, I suspect, because people on the internet like the feeling of knowing things that other people don't know, or feeling that they're doing things (or saying things) "how the pros do it", and believing the 4096×2160 true 4K thing makes them feel as though they have special cinema industry insider knowledge. Sadly, the entire thing was completely made up by consumers. Sorry to say.

 

"UHD" is not a name for 3840×2160

 

Secondly, UHD is not a name for 3840×2160. The whole "4096×2160 is 4K, and 3840×2160 is just called UHD" thing is entirely wrong; both of those resolutions are 4K resolutions, and in fact both of those resolutions are UHD resolutions as well. UHD is a term created by CEA as a marketing standard to refer to displays that meet certain requirements. Here is the relevant part of the definition of UHD:

 

UHD is basically a class of display; note that the definition is at least 3840×2160, and 16:9 or wider. This means that higher resolutions and wider ratios, such as 4096×2160, or even 5120×2880 or higher, or ultrawide resolutions, qualify as "UHD resolution". UHD does not have to be 3840×2160, or even a 4K class display at all.

 

3840×2160 is established as a standard by ITU, and it never defines "UHD" as 3840×2160. This is, again, something made up by the internet because it's simple and easy to say "4096 is 4K, and 3840 is UHD", so it catches on easily.

 

This standard does the exact same thing, establishing "4K" and "8K" as shorthand terms for discussing the formats in the context of the standards document. It does not mean 4K is "the name" for 3840×2160, just as the DCI specification's usage of the term does not mean 4K is "the name" for 4096×2160 either. It is just a general term used in the industry for anything ≈4,000 pixels horizontally, but of course may have specific meanings within certain standards documents, which are made clear in the documents themselves and only apply within that respective document.

 

There is no sense in which 3840×2160 is "just called UHD", or in which 4096×2160 is the "one true" 4K resolution.

 

"K" and "Ultrawide"

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"K" and "Ultrawide"

 

Every once in a while I see someone asking about "4K ultrawide", and what they mean by that is the most common 4K resolution (4K UHD, 3840×2160) extended horizontally to a ≈21:9 aspect ratio, so something like 5120×2160 (or four times 2560×1080).

 

Unfortunately this is really a misuse of the term "4K". Remember that 4K isn’t a name for a specific resolution like 3840×2160, so "4K ultrawide" doesn’t mean "that resolution, but wider". The "K" term refers to the width in pixels, so "something wider than 4K" would be called 5K. Saying "4K ultrawide" is like asking for an extra-wide 4-meter-wide table or something like that. "You mean...a 5-meter-wide table?" "No, a 4 meter table, but extra wide! Like maybe 5 meters in width!" "...Right..."

 

5120×2160, being ≈5,000 (5K) pixels horizontally, is a 5K resolution, so calling it "4K ultrawide" doesn’t really make sense. Terms like "1080p" and "1080p ultrawide", or "1440p" and "1440p ultrawide" work because the numbers 1080 and 1440 refer to the height rather than width, so when you have a resolution that is the same height but wider, you can still use the same number and it makes sense.

 

But a term like "2.5K" can’t just be used as a drop-in replacement for "1440p", because not all 1,440 pixel-tall screens have ≈2,500 pixels horizontally. Only 1440p screens with 16:9 ratios do. A 1440p screen with a wider ratio like 21:9 will have more horizontal pixels, which will classify it as a 3K or 3.5K resolution, even though the vertical pixel count (1440p) remains the same.

 

The same is true with 4K resolutions. A resolution like 3840×2160 (a 16:9 ratio) is a 4K resolution that could also be referred to as "2160p", but this does not mean "2160p" and "4K" are interchangeable. Extending 3840×2160 to a wider ratio like 21:9 results in a resolution that is still 2,160 pixels tall, but is 5K pixels wide instead of 4K. So even though "2160p ultrawide" still makes sense for that resolution, the "4K ultrawide" name does not.

 

"But if I can’t call it 4K ultrawide, what should I call it? If I say "5K", people will think I’m talking about 5120×2880 (16:9), and if I say 5K ultrawide then people will think I mean an ultrawide extension of that resolution, plus 5120×2160 is more like 5K ultrashort anyway..."

 

Usually it’s assumed when you say "4K" or "5K" that you’re talking about the 16:9 resolutions since they are the most common, so when people refer to different aspect ratios they’ll usually include the aspect ratio to avoid confusion. 5120×2160 can be referred to as as "5K 21:9" or something like that.

 

Another alternative that has been used is writing out both dimensions with "K" instead of just the horizontal. For example, 3840×2160 (4K UHD) is often called "4K × 2K". An ultrawide version of that resolution, 5120×2160, would be referred to as "5K × 2K", meanwhile the 16:9 resolution of 5120×2880 is referred to as "5K × 3K", so this convention does make the two resolutions distinguished from each other.

 

A third option (and probably the best option for most people) would be to not mix "K" and "ultrawide" together at all. Just use the old "vertical pixel count" convention and call it "2160p ultrawide".

 

Of course, you can always just write out the full resolution if you want to avoid any ambiguity, that option is always available too.

 

"But what about..."

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"But what about..."

 

Q: "But what about resolutions like 1280×720? Is that 1K? 1.5K? 1.25K? 1.28K? If we round to the nearest 0.5K, then it’s 1.5K, but then what about 1600×900? Is that also 1.5K?"

 

"K" is a casual shorthand, not a full-blown naming system. Typically it isn’t used at all for low resolutions like 1280×720, and there are some mid-range resolutions like 2304×1440 and 2880×1800 where people question how sensible this convention is (should 2560×1440 be called 2.5K while 2880×1800 and 3200×1800 are both 3K, even though 2880 is an equal distance between 2560 and 3200?).

 

The "K" shorthand originated in the cinema industry where discussions about resolution are generally centered around a few monolithic classes of resolutions, so this shorthand was never intended to be "high precision". If used for resolutions in the PC industry, yes there will be some that are ambiguous in what they should be called. If you’re talking about an unusual resolution, then it’s best to write out the full resolution rather than using abbreviations. These shorthands don’t cover every possible resolution and they were never intended to do so.

 

Q: "But if we round to the nearest 0.5K, shouldn’t 7680×4320 be called 7.5K rather than 8K? If it’s not 7.5K because you’re rounding to the nearest whole number, then 2560×1440 shouldn’t be 2.5K either!"

 

2560×1440 rounds up to 3K if using the nearest whole number, so you still don’t have any reason to call it 2K. Good try though.

 

This system of shorthands isn’t strictly defined by any industry body, and so there are no absolute rules. But the general consensus is that at the higher values (above 5K, usually) more "plus or minus" margin is given and we round to the nearest whole number instead of 0.5 value. At lower resolutions, it doesn't take as many pixels for two resolutions to be significantly different, so more granularity is needed to distinguish them, so we round to the nearest 0.5. There is no "definition" of where the absolute cutoff point is though.

 

For example if we rounded to the nearest 1K for all resolutions, then 1600×900 and 2304×1440 would both be considered "2K" resolutions, even though the difference between them is very significant. So instead, we round to the nearest 0.5K, and the names become 1.5K vs 2.5K, which gives a better representation of the difference. On the other hand if you had higher resolutions that were maybe 7680 vs. 8192, the difference isn’t really very significant (percentage-wise it's the same as the difference between 1920 and 2048), so there’s not much point in naming them to different categories.

 

Q: "Why are we suddenly using horizontal pixels anyway, vertical makes much more sense! The "4K" name is just marketing gibberish created by TV companies!"

 

The "K" shorthand was not created by TV companies. It is borrowed from the cinematography industry, where it has been used commonly for years prior to the introduction of 4K TVs to the consumer market. In cinematography, it makes much more sense to use horizontal resolution to classify images, because movies are often cropped vertically (black bars on top and bottom), so naming resolutions by vertical pixel count would mean the resolution classification of the material would change just based on how much black bar is added, even though the detail level of the image hasn’t changed. Since resolution is used to classify detail level, it doesn’t make any sense to have a classification system that changes designations when the detail level remains the same.

 

Instead, horizontal resolution is used to classify images, so that images with the same level of detail will be classified in the same group regardless of what aspect ratio has been chosen for the material.

 

However, in gaming, images are not cropped vertically when moving to a wider aspect ratio, but instead they are expanded horizontally because the content is rendered in real time, so it is possible to generate additional new content to fill the extra width rather than just expanding the existing image to fill the screen and cropping the top and bottom off. In this case classifying resolutions based on width alone isn’t all that useful, because the aspect ratio plays a much larger role in how the content appears on the screen.

 

But since the TV industry is more concerned with cinematic material than it is with gaming, they chose to use the "K" shorthand that is used in cinematography.

 

Q: "Ultimately a shorthand "means" whatever everyone agrees it means; if it’s universally accepted that "2K" means 2560×1440, and whenever you say 2K that’s what people interpret it as, then it DOES mean 2560×1440 no matter if it has logical basis or not!"

 

But everyone doesn’t agree that 2K means 2560×1440, that’s just the problem. Although "2K = 2560×1440" is becoming a widespread misconception among consumers, with people pointing to websites like Newegg and companies like ASUS starting to use the term "2K" to refer to 2560×1440, this is far from "universal agreement" on the meaning of 2K. It may be worth noting that Newegg also lists resolutions like 3440×1440 as "2K" which shows just how far out of touch they are; they’re just using "2K" as a drop in replacement term for "1440p" without any thought about it.

 

Within the cinematography industry, where this naming convention originated from in the first place, it is agreed without any ambiguity that "2K" refers to resolutions like 1920×1080 or 2048×1080, while 2560×1440 is definitely classed as a 2.5K resolution. Examples of this can be seen in the above section, "Examples of How the Cinematography Industry Uses These Terms".

 

 

or you can just call it 720p, 1080p 1440p, 4k, and 8k

or 2160p and 4320p if you're like that

 

just don't call it 1080p 1k and 1440p 2k, or you will get laughed at

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