Getting confused about resolution, please help ;)

Computers with retina screens allow you to choose from a wide variety of 'virtual' resolutions depending on whether you prefer 'more space' which will make things smaller, or 'larger text' if you prefer things bigger, or something in between. I doubt you will have any complaints with the options.

 

Lack of scaling built into OSX...

 

What he meant was that older OSX versions did not have scaling built in, as the modern versions do. If you run a modern OSX on an older high resolution MBP, then you would also get scaling now. (Assuming that they are supported, which I certainly assume they are)

 

The older screens pretty much only worked acceptably at their native resolution. If you put it any lower, everything would be overly blurry. This is still somewhat the case with the retina screens, but screen resolution is handled differently in two ways - first, with the majority of retina Macs, the native resolution is exactly 4x the actual resolution that will be used - so to get a 1440x900 desktop, Apple specs a 2880x1800 screen - this means that the scaling is perfect with little computational overhead, and remains very sharp. For any other resolutions, Apple uses some fancy scaling to achieve a result that is not quite perfectly sharp, but because of the high resolution of the screen, which means the pixel size is very small, it turns out 'acceptably' sharp for the majority of users who want either more desktop space or larger text.

In short, your old screen had relatively large native pixel size, and was not optimized to work at anything other than the native resolution, which at 1680x1050 on a 15" screen, could mean some elements are a bit small.

 

1440x900 was just an example. It can be any resolution that Apple chooses to work with.

 

Here's what my display preferences panel looks like on an imac 5k


Here's what happens when I press the option key when selecting Scaled.


Note that the default is 2560x1440.

And here's what happens when I tick the "Show low resolution Modes". Apparently "low resolution" doesn't take advantage of the extra pixels, so everything is as blurry as on a non retina mac.

I leave it on default. As much room and as readable as a 1440p display, but with an extra degree of sharpness and no visible anti-aliasing. It does not feel cramped or too small to read.

 

For the most part, the biggest advantage of a retina display is that it makes everything that is properly designed for it much sharper. Using the 'default' settings maximizes this sharpness.

 

Everything said here is true - but just to make it super simple: nothing will be tiny. Even without changing any settings, the physical size of everything on a Retina iMac is identical to everything on a non-Retina iMac (same size in points, just rendered with 4x more detail). Take text for example - it is exactly the same size, only sharper. In fact, the Retina model is EASIER on the eyes than the non-retina one (as a lot of people with poor eye-sight report).

The reason your MBP with 1680x1050 is tiny is because the difference in resolution was not enough to justify scaling in Apple's eyes. In other words, they designed it so that you get more screen space but with smaller sizes of everything. It's a bit hard to explain the difference, but all you need to know is that it's not the same as retina screens. In fact, current Retina MacBook Pro's have every UI element bigger in size (with more detail) even though their resolution is quite higher than your MBP.

 

It IS the 5K resolution, but the points are 2560x1440. What this means is that you have 4x as many pixels drawing something that is physically sized like a non-retina 2560x1440 screen. So, everything is the same SIZE as a 2560x1440 screen but drawn with 4x as much detail.

So, when you leave your iMac 5K at it's default setting you get the same size (as in, if you took a ruler and measured it on screen) as if you had a non-retina 2560x1440 screen (so, yeah, things are not super tiny). The difference is everything is 4x sharper and more precise. You will appreciate the sharpness without straining your eyes

 

You have to get past the old way of thinking of using monitors in native resolution vs scaled.

With retina you get BOTH, in essence, because it's a combo of a higher pixel density (PPI) AND software that is aware of that, and so displays things bigger so that you get the best of both worlds. Note I didn't necessarily mean "scaled" bigger, because that isn't what it does all the time.

Here's an example to make it clearer. I have a digital photo, say 4000x3000. On my regular 2560x1440 it will only fit if it is viewed at about half size, and even then it will probably require scrolling cuz I have to leave room for the interface of the program I'm using, all the menus, panels, etc, in something like Lightroom. If I want to show it at 1:1, pixel in image to pixel on screen, it's WAY big. Let's say I do that; now in the viewer in Lr I'm only seeing about half the horizontal and a third of the vertical pixels of the photo, since I need room for all of Lr's tools.

Now I move the Lr window from that 2560x1440 monitor to a 5k iMac. Whoa! the photo is still at 1:1, and is still 4kx3k, but now it almost ALL fits in the Lr window, with no scrolling needed. But automagically the user interface elements of Lr appear the SAME size as they do on the old iMac screen: their dimensions on the screen are the same, so a button that is 1cm on the 2.5k display is 1cm on the 5k display. Why? cuz the system knows that you want it that big so you can still see it, so with something like Lr it chooses a special hiDPI button image (it doesn't scale it; it has another hi res button in storage, and now uses it). That hiDPI button is TWICE as big, so on the retina screen it shows up as the same dimensions (1cm) as on the old iMac screen. That's what they mean by retina-aware. And it goes for web pages too: they can use icons, images, etc that are twice as big on retina, which means they'll appear the same dimensions as they did on that old iMac screen.

The same thing happens with icons and other elements of the OS X interface. A Safari icon is say 1cm square on both the 2.5k and 5k displays. But the dimension IN PIXELs is different; the 2.5k icon is say 100x100, the 5k is 200x200, 4x the size. And because it has more pixels, it can show more detail. Like a higher res DSLR photo vs an old smartphone photo. So on retina I can see all the little tick marks in the compass, and I can't see them on the 2.5k. It didn't SCALE the icon; it actually used another more hi res version of the icon.

 

2560x1440 HiDPI, meaning elements fit on a standard 2560x1440 pixel grid, but are rendered 4x as detailed. This is how HiDPI/Retina is meant to work-no physical size change for elements, but they look 4x as crisp. OS X handles this very well.

 

If I use it in 5k resolution, everything's very tiny.

If I use it in 2550x1440 resolution, everything's normally sized. But unlike a non retina 27 inch imac, each of those pixels is actually made of 4 smaller "mini-pixels". If the mac can render things (such as fonts, or photos, or 4K movies at a higher level of detail, it will take advantage of those smaller "mini-pixels" to make for crisper, more readable, more detailed graphics. It's rather like antialiasing. Except that instead of trying to simulate the extra resolution through grays, the extra resolution actually exists.

(And each of those minipixels is itself composed of the three "subpixels" that feature in "subpixel antialiasing", a less well developed and markedly inferior technology to make text more readable)

 

Of course you can zoom in. To view it the same size as on a non-Retina you would zoom in to 200%.

 

oops wrong thread

 

Note that what "100%" or "200%" actually means depends on the software, the format of the image and the physical size of your screen. Some file formats store the dimensions of images in "real world" units or the intended print resolution of images in pixels-per-inch.

Its a can of worms. The version of Photoshop Elements I have bases its "%" sizes on actual pixels, but if you choose "print size" it displays it at what would be "print size" if it was 1995 and your screen had a resolution of 72ppi*. Word does the same. 'Preview' seems to base its "%" sizes on actual print size, and also seems to have a better idea of the real size of a pixel, so it gets it more or less right).

(* Back in the day, when Apple only supported proprietary screens, all Apple screens were fixed at 72 ppi, so 1 pixel = 1 point - you couldn't change the resolution easily, if you wanted a 'higher' resolution you bought a bigger screen. )

 

I was curious about that, too, and made a test icon (attached) containing various resolutions to figure out which resolution is used where, by setting that icon on an app.

On a 5K iMac with default 2560x1440 virtual resolution and default dock size and size of icons in Finder views, it uses:

• 16@2x in Finder list view, and Get Info window bar - so it's actually using an icon that's 32x32 to fill a screen space of 16x16 virtual pixels, i.e. with much finer detail.
  
• 128@2x in Finder icon view - again using a huge 256x256 icon to fill a space apparently only 128x128, very neat.
  
• 32@2x is used in the Get Info top info
  
• 256 is used in the Get Info "preview" - not sure why it's not using a hi-res icon there.
  
• 512 is used in the Preview itself - not sure why it's not using a hi-res icon there.
  
• 512@2x is used in the task list, and on the dock on the left side if I have the app shortcut there - those places show the icon scaled down a lot, so I'm guessing the OS uses the biggest size so that the scaling has the most pixels to work with (and also, you could resize the dock to have larger icons)
  
• 128@2x is used as part of a running app's screenshot (if minimized) on the right side of the icon - this is scaled down and actually tiny, because it's only a part of the icon, so I guess 256x256 was deemed enough to work with.

The only thing I initially found a bit confusing is that if you open an image in Preview and you click on the 100% button (showing a "1" in a circle), the image takes up 1:1 virtual pixels, i.e. a 3000x2000 image is too big for the screen.
I guess it's because the idea is that the user thinks in virtual pixels, and it's only the system internally that makes use of the actual native resolution. So, if you display an image in Preview at 50%, the scaling should use the native pixels and end up effectively mapping the image 1:1 to native pixels - I haven't verified that though.

The last point in particular suggests to me that any app would have had to have at least minor changes made to it to be "retina-aware" and make optimal use of the available hi-res underlying the virtual pixels...?