I don't understand the iMac resolution

[jonatious]

So this is my first iMac and yes it is 5k. But Apple mentions that It looks best at half the resolution, lets say 2.5k, downscaling it by 2. So I don't get how 4 pixels forced to display the same color of a dot is better than 4 pixel being able to display 4 variants of the same color for the dot? Isn't that the whole point of high res displays?

The second question is what happens to my media at native 2.5k resolution? My desk background image? The videos I watch and the images/photos I edit? Are they all downscaled by 2?

I am pretty sure there is a valid reason for this. But I am just not getting it. Any insight is appreciated

For people who don't get it, the iMac ships and runs with 2560x1440 resolution by default and not the 5k resolution of the display

 

[SkiHound2]

5k is basically 2 x the 2560 x 1440 resolution in both dimensions. But think about how small text would be if displayed at that resolution on a 27" monitor. I'm writing this on a 2560 x 1440 monitor and the fonts and icons are about the right size for me. The 27" iMac monitor displays text and icons at the same size, but with with 4 pixels for every 1 displayed by my monitor. Just looks nicer and sharper. Because it's doubled it scales easily. The 4k 21.5" has pretty much the same screen quality, but 2560 x 1440 would make things too small for most of us on a 27" screen. 4k is essentially a doubling of 1080p in both dimensions (4 x the pixels). Scaling at resolutions that aren't native to the monitor (e.g, 4 k on a 5k monitor) can really tax the gpu and often doesn't look very good.

 

[Zandros]

No, the 27" iMac ships with a Hi-DPI mode setting that makes things look the same size as a traditional 2560x1440 monitor. Applications that are not aware of this will indeed be rendered by using four pixels of the same colour on the display for each pixel the app thinks it's using which looks kind of bad (but makes the app an usable size at least), but nowadays almost everything is aware and will use the full resolution available to them.

How videos and photos are rendered by default is up to the app (I think Preview will pixel-double everything when you tell it to zoom to native resolution, which is kind of weird), but be assured you are viewing all the data available.

With some trickery you can set the display to a 5160x2880 non-Hi-DPI mode, but everything will look really small.

 

[scottrichardson]

The whole hi-DPI thing can be confusing at first.

Allow me to help.

Think of there being two actual resolutions at play now. One is the pixel resolution, and one is the logical or perceived resolution measures in “points”.

So your iMac has a pixel resolution of 5120 x 2880 pixels.

And a logical point resolution is 2560 x 1440.

It renders elements on screen the same physical size as a non retina 2560 x 1440 monitor but with four times the density of pixels.

So the user interface elements and text will be twice as sharp, as there’s now four pixels available in the space where there would normally be one pixel.

Images or photos viewed at 100% will now occupy a quarter of the desktop space they used to.

So interface designers like myself now need to create artwork assets and images that are double the pixel count in both dimensions to ensure they take up the right amount of space when viewed at 100% on retina displays. So an icon that I want to “look like” a 100 x 100 pixel icon needs to be created at 200 x 200 pixels in photoshop. That 200 x 200 icon will take up the “space” of a 100 x 100 point icon.

 

[macduke]

All that is happening is that it makes everything look sharper at the same UI scale. Just like the iPhone and iPad. It’s basically a retina display.

Otherwise if you run at 1:1 5K scale your windows and text will be very small for only a 27” display.

 

[TheyCallMeBT]

I'll be going from a non retina 27" iMac to the 2019 27". When using Photoshop and setting up a canvas-- how does it appear? Like say I want to make an icon for a website at 250 x 250 px, 72 dpi. Is it going to appear like the 2560 x 1440 "logical" resolution, or is it going to be the actual pixel count at 5K?

 

[Fried Chicken]

Read anand’s article on the first Retina Macbook Pro.

He breaks it down.

 

[Crotonmark]

So what is the best display setting to see the best images on a 5k retina iMac?

 

[Zdigital2015]

So what is the best display setting to see the best images on a 5k retina iMac?

"Best for Display" or 2560X1440, which will be the most crisp resolution as it is @2x of 5120x2880, meaning divisible by two (2).
[doublepost=1556494733][/doublepost]

I'll be going from a non retina 27" iMac to the 2019 27". When using Photoshop and setting up a canvas-- how does it appear? Like say I want to make an icon for a website at 250 x 250 px, 72 dpi. Is it going to appear like the 2560 x 1440 "logical" resolution, or is it going to be the actual pixel count at 5K?

You have to choose between Points or Pixels, each pixel is two points when running @2x Retina resolution.

 

[Fried Chicken]

You have to choose between Points or Pixels, each pixel is two points when running @2x Retina resolution.

four*

 

[Fishrrman]

Zdigital wrote:
"You have to choose between Points or Pixels, each pixel is two points when running @2x Retina resolution."

Is not "retina" actually 2x2 ?
Double the pixels vertically, AND double horizontally?

Seems to me that "looks like" 2560x1440 would use 4 pixels for each "virtual pixel"...

 

[Zdigital2015]

four*

Zdigital wrote:
"You have to choose between Points or Pixels, each pixel is two points when running @2x Retina resolution."

Is not "retina" actually 2x2 ?
Double the pixels vertically, AND double horizontally?

Seems to me that "looks like" 2560x1440 would use 4 pixels for each "virtual pixel"...

Yes, I had a complete brain fart on that one...I was watching TV and answered in haste.

1 point = 2pixels, so a 1 point x1 point square on a Retina = 2 pixels x 2pixels. You are both correct, my apologies.

Here is a post that describes things in more detail for those that wish to explore the subject further - https://medium.com/@pnowelldesign/pixel-density-demystified-a4db63ba2922

 

[Eugen Mezei]

I need to see lots of charts (stock exchange) at the same time. So I looked for big monitors with even more important high resolution. So I bought two iMacs, late 2009 and mid 2011.
I would have liked Retina monitors, but they cost too much.

Now I found this thread.
Are you saying the Retina monitors would not offer me more "surface"? What I mean, can I not stuff more charts into the 27" than what I already can with the classic 27incher?
(Phyiscal size does not really matter, I sit close to the screen, so the charts can be tiny.)

 

[wilberforce]

I need to see lots of charts (stock exchange) at the same time. So I looked for big monitors with even more important high resolution. So I bought two iMacs, late 2009 and mid 2011.
I would have liked Retina monitors, but they cost too much.

Now I found this thread.
Are you saying the Retina monitors would not offer me more "surface"? What I mean, can I not stuff more charts into the 27" than what I already can with the classic 27incher?
(Phyiscal size does not really matter, I sit close to the screen, so the charts can be tiny.)

The retina 27" iMac default "resolution" is 2560x1440, so that the UI elements look the same size as a non-retina 2560x1440 monitor (but much sharper)

However you can set a "scaled" resolution up to 5120x2880 (twice the default), in which case all the text, windows, icons etc are all extremely tiny. You will need better than 20/20 vision to read it.

The next step down is 3200x1800, which is much more readable, but is only 25% more that the default 2560x1440.

 

[coolguy4747]

I need to see lots of charts (stock exchange) at the same time. So I looked for big monitors with even more important high resolution. So I bought two iMacs, late 2009 and mid 2011.
I would have liked Retina monitors, but they cost too much.

Now I found this thread.
Are you saying the Retina monitors would not offer me more "surface"? What I mean, can I not stuff more charts into the 27" than what I already can with the classic 27incher?
(Phyiscal size does not really matter, I sit close to the screen, so the charts can be tiny.)

A "retina" screen would show finer detail, so you could size your charts smaller than you could on a "non-retina" screen while still being legible.

 

[Eugen Mezei]

By pure luck I got me a retina iMac.
First thing I did, I updated to Monterey and installed Win10. (I would prefer Win8.1 but I already installed Monterey so it was to complicated to install 8.1 with Boot Camp.)

Monterey shows the resolutions not in absolute numbers but in more text, even more text, less text and even more less text.
I have no problem using the screen in native resolution. It is a bit tiny, but I can read everything.

In Win10 it is another story. In native resolution the writing is really tiny, unusable. If I put the resolution at 200% as recommended by Windows, than it is ok. In fact it is the resolution of the non-retina models.

What is the reason of this difference?

 

[Amethyst1]

I have no problem using the screen in native resolution.

What iMac do you have? And what setting did you select in macOS?

5120×2880 (native for 27") which is only available by holding [Alt] when clicking "Scaled", or "More Space", which corresponds to "Looks like 3200×1800" on a 27" iMac IIRC?

If you selected "More Space", that's the difference right there. A setting that simulates 3200×1800 real estate results in larger text and UI elements than running unscaled at 5120×2880 (e.g. in Windows at 100%).

In Win10 it is another story. In native resolution the writing is really tiny, unusable. If I put the resolution at 200% as recommended by Windows, than it is ok. In fact it is the resolution of the non-retina models.

Well, the screen is always driven at 5120×2880 (on a 27" iMac), so at 100%, everything is quite tiny. If you scale everything to 200% (twice as high and twice as wide), it looks like on a 2560×1440 screen, but much sharper. If you want the equivalent screen estate of macOS' "Looks like 3200×1800" mode, try a scaling factor of 5120/3200×100 = 160%.

 

[Eugen Mezei]

I have the 27", sorry I forgot to mention.

Yes, I selected more space. I just noticed that it says 3200x1800 when I pause the mouse for a second above that button.
Pressing Alt, did the trick, just as you described. Now it behaves identical to Windows.
Thank you for your help.

Lets see if I can get acostumed to this resolution. Remembers me to the tiny text on workstations, Suns eg.

 

[Eugen Mezei]

Btw, for me Retina looks not sharper. Could be it is the fault of the nano structure glass. I have it on the Retina screen but not on the older ones.