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A 4K 27-inch iMac is not a Retina iMac

PatriotInvasion

PatriotInvasion

macrumors 68000
Original poster
Jul 18, 2010
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Boston, MA
So we've been using the term "4K iMac" and "Retina iMac" interchangeably, but in reality they are different things. A 4K iMac at 3840x2160 is an improvement over 2560x1440 but the pixel density would only go from 109ppi to 163ppi. That's a nice to have, but it's not the life changing visual experience the Retina MacBook Pros or iOS devices had after being truly pixel-doubled to Retina.

Plus, a 4K 27-inch iMac would be nearly unusable at native resolution so you'd end up running it at "Best for Retina" which would simply be 1920x1080 HiDPI mode...essentially cutting the perceivable screen real estate vs what we have now. You could then scale the display for more space but you'd lose some of the crispness you bought it for. We're still very far off from 5120x2880 which would be a truly Retina version of the current 27-inch iMac so anyone holding out on buying a 27-inch in hopes for a Retina version may want to reconsider.
 
I agree, 5120x2880 even if apple does it with the screen, which GPU will power that much without skyrocking the prices? doesn't make sense to be honest. Rather get a mac pro with a 4k display.
 
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insane79 said:
I agree, 5120x2880 even if apple does it with the screen, which GPU will power that much without skyrocking the prices? doesn't make sense to be honest. Rather get a mac pro with a 4k display.
Click to expand...

When and if Apple releases an imac with a better display at 27", I'm quite sure they will have figured all this out to most of our satisfaction, regardless of what they "label" it.
 
A 4K iMac is somewhere in-between Retina and when Apple came out with the higher-res 1680x1050 15" MacBook Pro or when they made the 13.3" MacBook Air 1440x900 instead of the standard 1280x800 of the 13" MBP. It's an enhancement but not enough to make you do back flips for it. 5120x2880 is the game changer.

If you want a sneak peak into what "Retina" mode will be like on a 27" iMac just plug this into Terminal and then log out and log back in. Go to Display settings and select the 1280x720 (HiDPI) option. That will show you OS X in a Retina-like mode perfectly pixel doubling a 1280x720 res within the 2560x1440 native display. 4K would work the same way but would pixel double 1920x1080 instead of 1280x720. Everything just becomes bigger with more pixels available to draw objects more clearly.

sudo defaults write /Library/Preferences/com.apple.windowserver.plist DisplayResolutionEnabled -bool true
 
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People tend to sit further back from a 27" screen than a 15" or 7" screen so the effect will largely be the same. What makes a Retina display is that individual pixels are no longer decernable. Viewing distance is a BIG part of that.

Pixel density from smaller to larger Retina display:

iPhone 5(C/S), iPad mini 326ppi
iPad 3/4/A 264ppi
rMBP 13" 227
rMBP 15" 220

A 27" iMac could possibly be considered Retina at 4K or 163ppi.
 
flopticalcube said:
People tend to sit further back from a 27" screen than a 15" or 7" screen so the effect will largely be the same. What makes a Retina display is that individual pixels are no longer decernable. Viewing distance is a BIG part of that.

Pixel density from smaller to larger Retina display:

iPhone 5(C/S), iPad mini 326ppi
iPad 3/4/A 264ppi
rMBP 13" 227
rMBP 15" 220

A 27" iMac could possibly be considered Retina at 4K or 163ppi.
Click to expand...
Assuming that the "retina" 27" iMac will have a resolution of 5120 x 2880 that will be equal to 217 ppi. The current generation iMac ppi is about 108.
 
PatriotInvasion said:
We're still very far off from 5120x2880 which would be a truly Retina version of the current 27-inch iMac.
Click to expand...

What makes that resolution Retina? Retina is just a marketing gimmick created by Apple that doesn't have any actual standards. The whole premise behind Retina is that you can not distinguish individual pixels at a reasonable viewing distance. Nowhere has Apple claimed that the pixel count of some previously set, arbitrary standard has to be doubled in both dimensions. If Apple releases a 4k iMac, they will most likely call it a 4k iMac. If they release some other dimension, they will most likely call it a Retina iMac.

Either way, the standard is completely arbitrary. The current iMac could technically be a Retina iMac if Apple deemed a reasonable viewing distance to be 4-5 feet. This is a pointless argument about a meaningless standard.
 
Given the average distance a person would be sitting from an iMac's 27 inch screen, 3840x2160 is indeed retina.

Retina is a marketing word for a screen in which the pixels blend together and become indistinguishable to the eye per a certain distance. For a small screen like an iPhone, you need more PPI for that effect because you will be looking at it from a closer distance. For a large monitor like the iMac you only need around 160ppi for the same affect given an average viewing distance of 2 feet.

For a 60 inch 1920x1080 tv you can sit from 8 feet and beyond for that TV to become retina. Take a look at the specs for Apple's 'retina' macbook pros. Both sport 220ppi, but they're still retina if you view their screens from at least a foot away.
 
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I am guessing Apple will have to break their 2x factor HiDPi mode for 27" models. 4K is already demanding on mobile GPUs that it's really not realistic to expect 2880p display on iMac. With 163PPI, 1.5x factor HiDPi, 27" model can still achieve 1440p real estate and clearer display at the same time. Now, if they stuck a desktop GPU in them, they'd be another story but I don't see them moving to desktop GPU with current trend in their form-factor and their target market.
 
flopticalcube said:
Next year's 20(16?)nm Maxwell's should be able to do it. A 100W GPU will be the equivalent of today's desktop Titan or 780 which should be enough for 4K... just.
Click to expand...
I thought Maxwell mobile is mostly focused performance per watt?

I think it's 20nm, and 16nm won't happen anytime soon considering how long it took them to get down to 20nm...

But even if they do increase in performance and able to drive UI, it won't be enough to make 2880p realistic in gaming and other GPU intensive tasks are required.
 
It really does come down to distance. If you're like me, and run 2x 1440P 27" displays on your desk a bit further away than average, 4K will be more than enough to satisfy your "retina" desires. As far as screen real estate is concerned, I'm actually currently using SwitchResX to pump 3200x1800 to my 27s in HiDPI mode (meaning "looks like 1600x900"), which is then scaled down to 2560x1440 on the displays. I found I was, often as not, zooming in on Safari and increasing the size of the type elsewhere to get by in 2560x1440. But then, I operate a lot of my apps in full-screen. As such, a 27" 4K display in 1080p HiDPI mode would present more than enough screen real estate for a user like me.

That being said, Magic Trackpad gestures and bigger on-screen elements in full-screen are my happy place. Others won't feel that way. It clearly does depend upon how one works, and how close one sits to the display. A user with a single 27" who wants to use screen real estate to have multiple functional windows open at once would find "looks like 1600x900" or perhaps even "looks like 1080p" non-negotiable.

On the other hand, while my current HiDPI resolution isn't as sharp as it would look on a true 3200x1800 screen, it actually looks pretty great. Who knows? "Looks like 1440p" might be close enough for government work on at 4K. And given the increasing popularity of 27" true 1080p displays, I wouldn't be too shocked if Apple bit the 3280x2160 bullet on the 27". Especially since they're bundling that crazy-expensive 4K Sharp monitor with the current Mac Pros. 2880p would be astounding, but I'm not sure it's realistic.

Ironically, I think the most compelling argument against a 4K 27" iMac is what to do with the 21.5" iMac? Give it the same resolution? That seems distinctly unlike them. Bumping it to 1440p is a maybe, but pixel-doubling it just like was done with the MBPs seems tidier. Of course, Apple could take the opportunity to simply fundamentally change the iMac lineup for the first time since 2009. The broad ID hasn't really changed even since 2007. Single-SKU 25" 4K iMac, anyone?
 
Truthfulie said:
I thought Maxwell mobile is mostly focused performance per watt?

I think it's 20nm, and 16nm won't happen anytime soon considering how long it took them to get down to 20nm...
Click to expand...

It is but looking at the 28nm 60w part (750ti), it looks entirely feasible that we could see a 20nm (or 16nm if they are ready) next year that would be sufficient for 4K at around a 100W considering the current Kepler can do it around 230W.

But even if they do increase in performance and able to drive UI, it won't be enough to make 2880p realistic in gaming and other GPU intensive tasks are required.
Click to expand...
Yes, this is only for 2160. Even top-end desktop cards will have a tough time at 2880. I think Apple may well wait until all the stars align.
 
PatriotInvasion said:
So we've been using the term "4K iMac" and "Retina iMac" interchangeably, but in reality they are different things. A 4K iMac at 3840x2160 is an improvement over 2560x1440 but the pixel density would only go from 109ppi to 163ppi. That's a nice to have, but it's not the life changing visual experience the Retina MacBook Pros or iOS devices had after being truly pixel-doubled to Retina.

Plus, a 4K 27-inch iMac would be nearly unusable at native resolution so you'd end up running it at "Best for Retina" which would simply be 1920x1080 HiDPI mode...essentially cutting the perceivable screen real estate vs what we have now. You could then scale the display for more space but you'd lose some of the crispness you bought it for. We're still very far off from 5120x2880 which would be a truly Retina version of the current 27-inch iMac so anyone holding out on buying a 27-inch in hopes for a Retina version may want to reconsider.
Click to expand...


Who has been using the terms "4K iMac" and "retina iMac" interchangeably??

Not I. :)
 
mad3inch1na said:
What makes that resolution Retina? Retina is just a marketing gimmick created by Apple that doesn't have any actual standards. The whole premise behind Retina is that you can not distinguish individual pixels at a reasonable viewing distance. Nowhere has Apple claimed that the pixel count of some previously set, arbitrary standard has to be doubled in both dimensions. If Apple releases a 4k iMac, they will most likely call it a 4k iMac. If they release some other dimension, they will most likely call it a Retina iMac.

Either way, the standard is completely arbitrary. The current iMac could technically be a Retina iMac if Apple deemed a reasonable viewing distance to be 4-5 feet. This is a pointless argument about a meaningless standard.
Click to expand...

First, I understand the marketing aspect behind what the term "Retina" has become, but go ahead and watch how Steve Jobs first introduced it (skip ahead to the 1:50 mark of the video below). He clearly says that 300 pixels per inch is right around the threshold where the human eye can't detect pixels on the display. He does mention from about 10-12" away, but he and the Keynote slide behind him clearly focus on 300 ppi being the Retina threshold.

http://www.youtube.com/watch?v=kcnKi7GxZ2k

Regardless, part of my original point was that a 4K iMac would not be Retina in the way Apple has always done a Retina display...which is to pixel double a resolution so that you're left with an ultra crisp version of the same screen real estate. Because 5120x2880 is a pipe dream, we'd be left with a sort of half-the-way-there version of a Retina iMac...since pixel doubled 1920x1080 would be a real estate downgrade for 27" iMac users who are used to 2560x1440.
 
He says 300dpi specifically for the iPhone. He does say the eye can't differentiate more pixels after 300dpi, but you also have to sort of visualize your vision as a grid, and the closer a display is to your eye, the more pixels it must have as a single inch of it takes up a larger percentage of your vision (hence needing more dpi on the display itself.) The further away the display, the less percentage of your vision an inch of the display will take up, and thus the display needs less dpi to attain a retina effect.

Neither Apple or Steve Jobs has ever said a display has to be at least be 300dpi to be retina, again look at their retina macbook pros. Those are clearly labeled as retina displays and their dpi is only 220 or so.

This is a convenient and simple calculator that will tell you if something is retina or not. http://isthisretina.com
 
TMRaven said:
He says 300dpi specifically for the iPhone. He does say the eye can't differentiate more pixels after 300dpi, but you also have to sort of visualize your vision as a grid, and the closer a display is to your eye, the more pixels it must have as a single inch of it takes up a larger percentage of your vision (hence needing more dpi on the display itself.) The further away the display, the less percentage of your vision an inch of the display will take up, and thus the display needs less dpi to attain a retina effect.

Neither Apple or Steve Jobs has ever said a display has to be at least be 300dpi to be retina, again look at their retina macbook pros. Those are clearly labeled as retina displays and their dpi is only 220 or so.

This is a convenient and simple calculator that will tell you if something is retina or not. http://isthisretina.com
Click to expand...

Still, there seems to be some truth to what SJ was saying. On the 326 ppi iPhone 5s in front of me, I cannot detect a single pixel regardless of viewing distance. Forget 10-12"...I can put my eyeball up to the display and can't make out one single pixel. There must be a point where the pixel almost becomes microscopic and that's what the original Retina Keynote first alluded to. This is not true for my work issued 15" rMBP in front of me. If I lean forward and look hard enough, I can pinpoint a single pixel.

Even the link you provided admits that all displays can be Retina displays if you sit far enough away. It seems then that the 300ppi marker is sort of the true definition of what Apple was really hinting at originally back in 2010 with the iPhone 4 announcement. Over time, Retina has become the marketing term for any pixel doubled display on an Apple device regardless of final ppi count though...I get that.

Lastly, a 4K iMac marketed as Retina would almost surely come default with a 1920x1080 real estate in HiDPI mode...a downgrade over the existing screen real estate of the 2560x1440 27" iMac.
 
PatriotInvasion said:
Still, there seems to be some truth to what SJ was saying. On the 326 ppi iPhone 5s in front of me, I cannot detect a single pixel regardless of viewing distance. Forget 10-12"...I can put my eyeball up to the display and can't make out one single pixel. There must be a point where the pixel almost becomes microscopic and that's what the original Retina Keynote first alluded to. This is not true for my work issued 15" rMBP in front of me. If I lean forward and look hard enough, I can pinpoint a single pixel.

Even the link you provided admits that all displays can be Retina displays if you sit far enough away. It seems then that the 300ppi marker is sort of the true definition of what Apple was really hinting at originally back in 2010 with the iPhone 4 announcement. Over time, Retina has become the marketing term for any pixel doubled display on an Apple device regardless of final ppi count though...I get that.

Lastly, a 4K iMac marketed as Retina would almost surely come default with a 1920x1080 real estate in HiDPI mode...a downgrade over the existing screen real estate of the 2560x1440 27" iMac.
Click to expand...



I can see pixels on my iPhone 4s. The 15" Retina macbook pro by your definition has less real estate then my 2011 macbook pro (1440 X 900 vs 1650 x 1050) and therefore also a downgrade from the old ones. The 13" retina has less real estate then the 13" macbook air also by your definition.
 
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cfedu said:
The 15" Retina macbook pro by your definition has less real estate then my 2011 macbook pro (1440 X 900 vs 1650 x 1050) and therefore also a downgrade from the old ones. The 13" retina has less real estate then the 13" macbook air also by your definition.
Click to expand...

Both true statements, but that higher real estate 15" MBP was never the base configuration but rather an orphan add on that cost a $50 premium mainly to appease those who wanted a matte display.

The MacBook Air and 13" Retina MBP are different products. The 13" MBP always had a 1280x800 real estate before going Retina but I see your point and that's why I think Apple will ultimately follow this path on a 4K iMac...1920x1080 in HiDPI mode. But it would be the first time they've downgraded real estate on a base config when going Retina (on the 27").
 
PatriotInvasion said:
So we've been using the term "4K iMac" and "Retina iMac" interchangeably, but in reality they are different things. A 4K iMac at 3840x2160 is an improvement over 2560x1440 but the pixel density would only go from 109ppi to 163ppi. That's a nice to have, but it's not the life changing visual experience the Retina MacBook Pros or iOS devices had after being truly pixel-doubled to Retina.

Plus, a 4K 27-inch iMac would be nearly unusable at native resolution so you'd end up running it at "Best for Retina" which would simply be 1920x1080 HiDPI mode...essentially cutting the perceivable screen real estate vs what we have now. You could then scale the display for more space but you'd lose some of the crispness you bought it for. We're still very far off from 5120x2880 which would be a truly Retina version of the current 27-inch iMac so anyone holding out on buying a 27-inch in hopes for a Retina version may want to reconsider.
Click to expand...

Wrong.

A 4k panel at 27" on an iMac would definitely be retina.

The current 2560x1440 resolution is almost retina at the optimal viewing distance from the screen - it's 80% to 90% of the way to being retina as it is. Going to 4k resolution would be more than adequate - at a 21" viewing distance a 27" 4k panel is a retina screen.

You don't need 5120x2880 for "truly" retina, since retina simply means "the inability to distinguish individual pixels" - for a 4k 27" panel this distance occurs at 21 inches - well inside the viewing distance for a 27" panel, so a 4k 27" screen is already "truly retina".
 
joe-h2o said:
Wrong.

A 4k panel at 27" on an iMac would definitely be retina.

The current 2560x1440 resolution is almost retina at the optimal viewing distance from the screen - it's 80% to 90% of the way to being retina as it is. Going to 4k resolution would be more than adequate - at a 21" viewing distance a 27" 4k panel is a retina screen.

You don't need 5120x2880 for "truly" retina, since retina simply means "the inability to distinguish individual pixels" - for a 4k 27" panel this distance occurs at 21 inches - well inside the viewing distance for a 27" panel, so a 4k 27" screen is already "truly retina".
Click to expand...

I think truly retina means a very crisp, clear screen... and that an inability to distinguish individual pixels is just part of that.

Another important part of that, as OP points out, is the the pixel doubling.

So, while you don't need 5120x2880 @ 27" for the sake of pixel size (for most of us), you do need it to double the pixels without losing screen real estate vs. the current iMac.

Personally, I think the 27" iMac has an overabundance of screen real estate, so I'd be willing to give up some... but not to the degree of 1920x1080 (which pixel doubles to 3840 x 2160). Also, I suspect that's not quite retina even by the pixel distinguishing rule for most of us... just a guess though... maybe 4K at ~23" would do it?

Anyway, you're all welcome to define retina any way you want, but if the display quality isn't there, then what's the point?
 
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