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Author Topic: Mac OS X scaling 4K monitors  (Read 33817 times)

Hans Kruse

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Mac OS X scaling 4K monitors
« on: August 11, 2015, 03:43:44 pm »

Hans Kruse

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Re: Mac OS X scaling 4K monitors
« Reply #1 on: August 14, 2015, 09:28:11 am »

I'm surprised nobody had commented on this :)

Tim Lookingbill

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Re: Mac OS X scaling 4K monitors
« Reply #2 on: August 14, 2015, 03:01:50 pm »

I would've commented, Hans, but I don't have a 4K Retina display. I kept ignoring the topic going by the title.

I'm stuck with a 1080 LG 27" hooked to a 2010 Mac Mini. I don't have your problem and frankly your outline of your issue was quite difficult to keep straight in my head due to your detailed account of what 4K scaling does to 1:1 previews in Lightroom.
 
I can only think about how tiny each RGB pixel site looks on a 4K screen and trying to visualize how Lightroom is going to draw all those high rez DSLR pixels contained in your images to screen dots that can't even be seen because they're too small. The antialiasing preview algorithms for scaling up or down has got to be a nightmare.

Even on my 6MP DSLR images at 1:1 LR previews don't give me an idea how sharp it's going to look when I downsize it for web display. I zoom down to a level that invokes antialiasing that gives the closest match to downsampling to 700 pixels on the long end to give me an idea how sharp to make the image.

I also have output sharpening set to Glossy Paper/High whose affect doesn't show up in 1:1 previews. See? Look at all the variables I just came up with. It's confusing as hell.
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Hans Kruse

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Re: Mac OS X scaling 4K monitors
« Reply #3 on: August 15, 2015, 07:27:18 am »

I would've commented, Hans, but I don't have a 4K Retina display. I kept ignoring the topic going by the title.

I'm stuck with a 1080 LG 27" hooked to a 2010 Mac Mini. I don't have your problem and frankly your outline of your issue was quite difficult to keep straight in my head due to your detailed account of what 4K scaling does to 1:1 previews in Lightroom.
 
I can only think about how tiny each RGB pixel site looks on a 4K screen and trying to visualize how Lightroom is going to draw all those high rez DSLR pixels contained in your images to screen dots that can't even be seen because they're too small. The antialiasing preview algorithms for scaling up or down has got to be a nightmare.

Even on my 6MP DSLR images at 1:1 LR previews don't give me an idea how sharp it's going to look when I downsize it for web display. I zoom down to a level that invokes antialiasing that gives the closest match to downsampling to 700 pixels on the long end to give me an idea how sharp to make the image.

I also have output sharpening set to Glossy Paper/High whose affect doesn't show up in 1:1 previews. See? Look at all the variables I just came up with. It's confusing as hell.

A 4K screen has 4x more pixels than yours and the Dell 32" monitor is a bit larger, but it is probably not worthy of being called retina since the PPI is much less than the 15" MacBook Pro retina screen or the 27" 5K display on the new iMac. The PPI of the 32" 4K display is 138. The PPI of the MacBook Pro 15" is 220. In comparison a "standard" 30" 2560x1600 display is 100 PPI.

The reason I wrote this up was to make others aware of the issue of scaling in OS X relative to 1:1 display in Lightroom which is to judge pixel level sharpness in your photos. I felt it would be useful to make others aware of this, if they had not already seen this issue. I could also be read as a warning against getting a 4K display.

I don't have an iMac 5K but I would expect that with the resolution set to default which is 2560x1400 that 1:1 would map pixels from the image to the screen pixels 1:1, but other scaled resolutions would not and therefore make the 1:1 the wrong size on the screen.

You other sharpening considerations has in my opinion not really anything to do with the issue I brought up :)

Tim Lookingbill

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Re: Mac OS X scaling 4K monitors
« Reply #4 on: August 15, 2015, 02:59:11 pm »

Thanks for the clarification, Hans.

I now understand that this is a image frame size scaling issue that doesn't induce any antialiasing artifacts caused by various zoom levels including 1:1 previews.

So you're getting accurate looking previews with regard to image detail captured in accordance with image resolution.

The frame size of the entire image isn't scaling consistently between imaging apps and another display? Is that the issue?

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Wayne Fox

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Re: Mac OS X scaling 4K monitors
« Reply #5 on: August 15, 2015, 04:58:43 pm »

interesting. I think I know what your saying, but LR is supposed to be "retina display" aware which  means it should be able to take advantage of full resolution when it wants to  (like 1:1 zoom).  So wondering if this is because the Dell is not considered a retina display (to be honest, 138 pip is closer to a normal display than a retina display).  Does a 5k iMac or a rMBP show this same problem?
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Hans Kruse

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Re: Mac OS X scaling 4K monitors
« Reply #6 on: August 15, 2015, 06:03:17 pm »

interesting. I think I know what your saying, but LR is supposed to be "retina display" aware which  means it should be able to take advantage of full resolution when it wants to  (like 1:1 zoom).  So wondering if this is because the Dell is not considered a retina display (to be honest, 138 pip is closer to a normal display than a retina display).  Does a 5k iMac or a rMBP show this same problem?

Well, that was why I was surprised. Dell is a 4K display and there is no reason to believe that another 4K display will be different. It really nothing to do with the PPI as another 4K display like the Dell 24" has a much higher PPI. The MBP retina display is also showing the same issue as I mentioned in my post. Only with the default resolution option will 1:1 in Lightroom be really be mapped 1:1 to screen pixels. This is btw. also documented here (as I found later on) http://macperformanceguide.com/mbpRetina2012-retina.html
I have not tried the iMac 5K but I'm sure it is the same issue.
« Last Edit: August 15, 2015, 06:07:29 pm by Hans Kruse »
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Hans Kruse

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Re: Mac OS X scaling 4K monitors
« Reply #7 on: August 15, 2015, 06:10:43 pm »

Thanks for the clarification, Hans.

I now understand that this is a image frame size scaling issue that doesn't induce any antialiasing artifacts caused by various zoom levels including 1:1 previews.

So you're getting accurate looking previews with regard to image detail captured in accordance with image resolution.

The frame size of the entire image isn't scaling consistently between imaging apps and another display? Is that the issue?



What I'm saying is that I only get 1:1 displayed as 1:1 to screen pixels when using the default scaling option. Other scaling options do not do that. This means that the detail does not look as good as with the default option. This is in contrast with the general understanding that images with high resolution displays where there are scaling options that the native resolution of the display is used. This is not the case.

KarlGohl

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Re: Mac OS X scaling 4K monitors
« Reply #8 on: August 21, 2015, 07:35:32 pm »

Just want to let readers of this thread know that in Hans' original thread (in the Computers forum) he and I have pretty much figured out what is happening.  The key take-aways are:
- This is a result of the "looks like" scaled resolutions offered in Display Preferences.
- This is not a LR bug
- If you want to view an image in LR such that a pixel in the image is displayed by exactly one pixel on the display, you need to set your Display Prefs to either the full resolution of your display (which will make UI elements very small) or to the "Looks like" resolution that is exactly half of your display's resolution. 
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Hans Kruse

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Re: Mac OS X scaling 4K monitors
« Reply #9 on: August 22, 2015, 09:33:42 am »

Just want to let readers of this thread know that in Hans' original thread (in the Computers forum) he and I have pretty much figured out what is happening.  The key take-aways are:
- This is a result of the "looks like" scaled resolutions offered in Display Preferences.
- This is not a LR bug
- If you want to view an image in LR such that a pixel in the image is displayed by exactly one pixel on the display, you need to set your Display Prefs to either the full resolution of your display (which will make UI elements very small) or to the "Looks like" resolution that is exactly half of your display's resolution. 

Thanks Karl for updating this thread as well. Probably even the most important one since Lightroom users really should be aware of the scaling consequences for 1:1 views in Lightroom.

This basically means that on the MacBook retina displays only the default resolution of 1440x900 will show 1:1 as one image pixel on one display pixel. On the iMac retina it would be the default 2560x1440 resolution.
On a 4K display there are two options: One is the 1920x1080 resolution or the default full resolution of 3840x2160. Any other scaling option will not display one image pixel as one display pixel.

This display resolution (scaling) can be changed at any time while applications are running and they will resize the windows or just map the windows to the new resolution. I'm sure that many readers will be puzzled about this so just accept that this is the way it is  ;D and alternatively read the following https://developer.apple.com/library/mac/documentation/GraphicsAnimation/Conceptual/HighResolutionOSX/Introduction/Introduction.html

hokuahi

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Re: Mac OS X scaling 4K monitors
« Reply #10 on: August 22, 2015, 01:23:47 pm »

Just want to let readers of this thread know that in Hans' original thread (in the Computers forum) he and I have pretty much figured out what is happening.  The key take-aways are:
- This is a result of the "looks like" scaled resolutions offered in Display Preferences.
- This is not a LR bug
- If you want to view an image in LR such that a pixel in the image is displayed by exactly one pixel on the display, you need to set your Display Prefs to either the full resolution of your display (which will make UI elements very small) or to the "Looks like" resolution that is exactly half of your display's resolution.  

Just to be very clear on this, there's absolutely no way then that one can have the full resolution of a 4K display and be able to read the UI elements in Photoshop and/or Lightroom at their 'normal' size at the same time?
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Hans Kruse

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Re: Mac OS X scaling 4K monitors
« Reply #11 on: August 22, 2015, 01:27:25 pm »

Just to be very clear on this, there's absolutely no way then that one can have the full resolution of a 4K display and be able to read the UI elements in Photoshop and/or Lightroom at their 'normal' size at the same time?

As I mentioned in the post just above, there are two choices on a 4K monitor: half resolution and full resolution which will render 1:1 at the right size in LR. 1920x1080 and 3840x2160. It is possible to read text at 4K resolution on a 32" monitor but they are very small.

Tim Lookingbill

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Re: Mac OS X scaling 4K monitors
« Reply #12 on: August 22, 2015, 02:53:42 pm »

As I mentioned in the post just above, there are two choices on a 4K monitor: half resolution and full resolution which will render 1:1 at the right size in LR. 1920x1080 and 3840x2160. It is possible to read text at 4K resolution on a 32" monitor but they are very small.

I don't know about third party app interfaces with regard to UI text and icon sizes but the OS X Finder does have under menu View>Show View Options... the ability to increase UI font and icon size.

Apple has got to have provided a better UI viewing tool option for ALL apps or else there's no point to having 4K resolution if no one can use it to do basic navigating of apps and OS.

I hope it's not having to rely on using "Universal Access" in OS X's System Preferences. I'm on OS 10.6.8 so I don't know if newer versions done away with this UI tool or renamed or moved it under some "Appearance" Preference section that is meant to be used for those with less than perfect vision.
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Hans Kruse

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Re: Mac OS X scaling 4K monitors
« Reply #13 on: August 22, 2015, 04:08:11 pm »

I don't know about third party app interfaces with regard to UI text and icon sizes but the OS X Finder does have under menu View>Show View Options... the ability to increase UI font and icon size.

Apple has got to have provided a better UI viewing tool option for ALL apps or else there's no point to having 4K resolution if no one can use it to do basic navigating of apps and OS.

I hope it's not having to rely on using "Universal Access" in OS X's System Preferences. I'm on OS 10.6.8 so I don't know if newer versions done away with this UI tool or renamed or moved it under some "Appearance" Preference section that is meant to be used for those with less than perfect vision.

As mentioned earlier on there are scaling options as attached which scales visual elements like menues and text. graphics gets scaled to the resolution of the backing store.

Maybe it is difficult to understand this if you don't have a system that has a high resolution display, but the choices Apple have made does really work well. One just need to understand how this impacts image oriented applications like Lightroom and Photoshop if you want to have pixels in images display 1:1 to pixels on the display. You don't have to adjust text sizes in individual applications.

If you have a retina MacBook Pro of an iMac retina just use the default resolution (which really is default!) and all is well. However if you choose a different scaling option then all will look great, but 1:1 is no longer exactly 1:1 as mentioned. For 4K it is different since default is full resolution 4K and therefore one need to understand how this works. For the Apple supplied display options it is easy since Apple have chosen display sizes and resolutions that work well with the socalled default resolution.

Tim Lookingbill

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Re: Mac OS X scaling 4K monitors
« Reply #14 on: August 22, 2015, 04:37:35 pm »

...but 1:1 is no longer exactly 1:1 as mentioned.

Oh, so there really is no problem here with 4K UI. I see.
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Hans Kruse

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Re: Mac OS X scaling 4K monitors
« Reply #15 on: August 22, 2015, 04:40:57 pm »

Oh, so there really is no problem here with 4K UI. I see.

What are you trying to say?

Tim Lookingbill

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Re: Mac OS X scaling 4K monitors
« Reply #16 on: August 22, 2015, 05:28:27 pm »

What are you trying to say?

That one can't see pixels that appear microscopic both in a high rez image and 4K display to determine 1:1 pixel mapping to screen. One can only see the frame size differences when switching from native display resolution between two displays of different size and pixel resolution.

I have the same issue with my two displays that have different native resolutions and panel sizes. My solution is to only use my 27" display and retire the 22" higher resolution display to my closet. I don't need two gigantic displays to edit my images.
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Hans Kruse

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Re: Mac OS X scaling 4K monitors
« Reply #17 on: August 22, 2015, 05:57:01 pm »

That one can't see pixels that appear microscopic both in a high rez image and 4K display to determine 1:1 pixel mapping to screen. One can only see the frame size differences when switching from native display resolution between two displays of different size and pixel resolution.

I have the same issue with my two displays that have different native resolutions and panel sizes. My solution is to only use my 27" display and retire the 22" higher resolution display to my closet. I don't need two gigantic displays to edit my images.

But you do understand what was pointed out in the thread?
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