# Lightroom Display size with 4K display



## Leadfoot (Nov 23, 2015)

I have recently upgraded to a 4K monitor (Dell P2715Q), which is 3840x2160 natively, and I use it on a MacPro at mostly 3008x1692.

In LR 6.1 and 6.3, Help->System info, it shows the display as double this, 6016x3384.
In addition, LR->Catalog Settings->File Handling, shows the "auto" preview size to be this, 6016x3384.

If I switch the 4K display to 2560x1440, again, it's doubled in LR in the System Info and "auto" preview size.

All the other non-4K displays I tried (1920x1080, 2560x1600, and an Macbook Pro 2880xsomething) show the correct size in LR, but not with the 4K display.

Anyone have any ideas?  I think the display size effects preview generation, and sometime I notice thinks like scrolling in Grid view, etc are very laggy.
Could this have something to do with how Mac OS scales for "retina" quality display?

mid-2010 MacPro, 7970 display board, running Yosemite 10.10.5

BTW, the Dell P2715Q is a fantastic monitor - the image quality is just stunning.


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## Jim Wilde (Nov 23, 2015)

What does it show if you run the monitor at the native 3840x2160?


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## Leadfoot (Nov 23, 2015)

Mac OS Yosemite doesn't give me the option at 3840x2160 in Preferences->Display.  The highest option is 3200x1800, and again, it's doubled in LR to 7400x3600, both System info Display size, and "auto" preview size.

[I'm not sure if this is a bug in Mac OS, ie not being able to use full 3840x2160.  I can force it by using a third party tool called SwitchResX (I think), but it's not very useful, as 3840x2160 is too high a resolution and everything is too small to be usable without a magnifying glass]


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## Jim Wilde (Nov 23, 2015)

OK, thanks. Unless another 4k user has some insight into the problem, I'd suggest sticking in a bug report at the official Adobe feedback site (link at the top of the page).


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## clee01l (Nov 23, 2015)

Leadfoot said:


> Mac OS Yosemite doesn't give me the option at 3840x2160 in Preferences->Display.  The highest option is 3200x1800, and again, it's doubled in LR to 7400x3600, both System info Display size, and "auto" preview size.
> 
> [I'm not sure if this is a bug in Mac OS, ie not being able to use full 3840x2160.  I can force it by using a third party tool called SwitchResX (I think), but it's not very useful, as 3840x2160 is too high a resolution and everything is too small to be usable without a magnifying glass]


In OS X System Preferences, what happens when you choose "Default for Display"  instead of a Scaled Resolution? What resolution do you get?  What is the diagonal size of your new monitor (in inches)?

You might need to upgrade to ElCapitan — OS X 10.11.1, since it has been tuned to accommodate 4 & 5 K displays. The problem with HiDPI displays is the increased pixel density. If a character (say the letter "M") is displayed *by an app* on a standard monitor of 120dpi, it's size will be ~1/10" in a side.  The same letter "M" displayed on a HiDPI monitor of 240 dpi, it size will be ~1/20" and take up a square 1/4 the size on the standard display (120dpi).   This is the geometry problem that applications need to overcome.  If the OS or the app being executed can't adapt to  HiDPI screens, then you need to down grade the resolution of the monitor.  This defeats the purpose of getting the 4K monitor to begin with.  You will want your app to adjust the size of the displayed fonts, buttons and icons so that HiDPI monitor display fonts, buttons and icons at a comfortable viewing size but with greater fidelity due to the higher resolution. 
I would recommend the upgrade to OS X 10.11.1 to see if these issues go away. With the OS X API for windows controls used by all apps including LR you may see better fidelity

I do not have an explanation as to why your LR screen resolution is double the actual. (mine mirrors my display numbers in system preferences (which are set for the "Default for the Displays") I don't have a 4 K monitor  and I often resort to using {Cmd}{+} to zoom text to a readable size. (it doesn't help with windows controls or menus, but it makes the high res 27" (2560X1440) screen usable and I still get to see photos with full fidelity.


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## Leadfoot (Nov 23, 2015)

Thanks Cletus, was hoping you'd respond.

Preferences->Display:  Default is 1920x1080, LR is 2x this in LR Help->System info Display size and preview size.
For all resolution choices in Preferences->Display, Scaled, LR is 2x

Now, if you hold the Option key down, and click on "Scaled" in System Preferences->Display, more resolution options magically appear:







The "(low resolution)" options all appear as well some additional normal resolution options.  The native resolution, 3860x2160, has no "(low resolution)" option.

For any "(low resolution)" option, the LR System info and "auto" preview size, is not 2x, but the correct size and matches the display. However, the display becomes fuzzy, which defeats the purpose of a 4K display.
For any normal resolution, ie not "(low resolution)", the LR System info Display size, and "auto" preview size is 2x the Display resolution.

The only option that seems correct, where the screen resolution matches the LR sizes, is the native resolution of the display, 3860x2160.  This isn't practical, since everything is too small.

It appears you are correct Cletus, LR and Mac OS (Yosemite) don't seem to play well with this particular display. The "(low resolution)" options is Mac OS down sampling the pixels for a lower resolution display, thus making the display fuzzy.

If I had to guess, I think it's a LR bug, and not seeing that the 4K monitor is a Retina display.  I've never seen anything like this anywhere else...


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## clee01l (Nov 24, 2015)

Is the native resolution for your monitor 3840x2160 and does your Video card support that resolution? I'm guessing that it does not. How is the monitor connected? HDMI? DisplayPort? (both digital) VGA? (analog). 

Can you copy and paste the System Info screen from LR into a reply here?   I'm still thinking that you should update to ElCapitan.


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## Leadfoot (Nov 24, 2015)

Thanks for your advice and assistance, much appreciated.

The native resolution of the P2715Q monitor is 3840x2160, and I'm driving it with a HD 7970 graphics card.  It's connected via miniDP to DP cable.

Your suggestion about updating to El Capitan is a good one, but not one I'm prepared to make until a few more iterations of the OS come out.

Here is the System Info from LR.  I'm currently running at 3008x1692, and you can see LR thinks the display is two times this.

Lightroom version: 6.3 [ 1052427 ]
License: Perpetual
Operating system: Mac OS 10
Version: 10.10 [5]
Application architecture: x64
Logical processor count: 12
Processor speed: 3.3 GHz
Built-in memory: 32,768.0 MB
Real memory available to Lightroom: 32,768.0 MB
Real memory used by Lightroom: 795.6 MB (2.4%)
Virtual memory used by Lightroom: 1,434.9 MB
Memory cache size: 1,026.6 MB
Maximum thread count used by Camera Raw: 12
Camera Raw SIMD optimization: SSE2
Displays: 1) 6016x3384

Graphics Processor Info: 
AMD Radeon HD Tahiti XT Prototype OpenGL Engine

Check OpenGL support: Passed
Vendor: ATI Technologies Inc.
Version: 4.1 ATI-1.32.25
Renderer: AMD Radeon HD Tahiti XT Prototype OpenGL Engine
LanguageVersion: 4.10


Application folder: /Applications/Adobe Lightroom
Library Path: /Volumes/Data/LR Catalogs/Photos LR6.lrcat
Settings Folder: /Users/XXX/Library/Application Support/Adobe/Lightroom

Installed Plugins: 
1) Aperture/iPhoto Importer Plug-in
2) Canon Tether Plugin
3) Facebook
4) Flickr
5) HDR Efex Pro
6) HDR Efex Pro 2
7) jf Metadata Wrangler
8) Leica Tether Plugin
9) LRT Export 4
10) Nikon Tether Plugin

Config.lua flags: None

AudioDeviceIOBlockSize: 512
AudioDeviceName: Built-in Output
AudioDeviceNumberOfChannels: 2
AudioDeviceSampleRate: 44100
Build: Uninitialized
CoreImage: true
GL_ACCUM_ALPHA_BITS: 0
GL_ACCUM_BLUE_BITS: 0
GL_ACCUM_GREEN_BITS: 0
GL_ACCUM_RED_BITS: 0
GL_ALPHA_BITS: 8
GL_BLUE_BITS: 8
GL_DEPTH_BITS: 24
GL_GREEN_BITS: 8
GL_MAX_3D_TEXTURE_SIZE: 16384
GL_MAX_TEXTURE_SIZE: 16384
GL_MAX_TEXTURE_UNITS: 8
GL_MAX_VIEWPORT_DIMS: 16384,16384
GL_RED_BITS: 8
GL_RENDERER: AMD Radeon HD Tahiti XT Prototype OpenGL Engine
GL_SHADING_LANGUAGE_VERSION: 1.20
GL_STENCIL_BITS: 8
GL_VENDOR: ATI Technologies Inc.
GL_VERSION: 2.1 ATI-1.32.25
GL_EXTENSIONS: (I deleted these...)


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## Leadfoot (Nov 26, 2015)

Ok, I installed El Cap, and the same problem exists for 6.0, 6.1.1 and 6.3 - the Lightroom Display size is always 2x the real display size on the 4K monitor.

Any ideas?


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## clee01l (Nov 27, 2015)

Leadfoot said:


> Ok, I installed El Cap, and the same problem exists for 6.0, 6.1.1 and 6.3 - the Lightroom Display size is always 2x the real display size on the 4K monitor.
> 
> Any ideas?


None whatsoever. ????  If you disconnect the 4K monitor, Does the Display size still show double?


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## Leadfoot (Nov 27, 2015)

No difference, Yosemite, El Cap, and LR version, all show Lightroom Display size is always 2x the real display size.

If I connect a non-4K display in addition to the 4K, LR can see both: The non-4K at it's native resolution, and 4K at 2x the real display size.  The only time LR detects the correct display size (other than HiDPI resolutions, which just downscales it for non-retina displays I think) is when Mac OS sets the display size to the native resolution, 3840x2160.

As a wild guess, LR asks the Mac OS what the display resolution is, and probably the maximum resolution of the display.  And LR interprets this to be a non-retina display (ie low resolution), and then doubles the size, so then when it's displayed, it gets down sampled by the Mac OS.  Essentially, LR thinks this 4K display is a non-retina display.


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## Johan Elzenga (Dec 6, 2015)

I believe I can shed some light on this problem. If you use a lower resolution setting on a 4K monitor, the system uses a little trick to keep the result as crisp as possible. Just sending the lower resolution image to the monitor would cause it to be blurry, so the system first renders the image at four times the resolution (twice the width and twice the height) and then this image gets resized to the native resolution of the display. Apparently Lightroom gets confused by this trick and thinks that the monitor is really four times the resolution setting.


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## clee01l (Dec 6, 2015)

JohanElzenga said:


> Apparently Lightroom gets confused by this trick and thinks that the monitor is really four times the resolution setting.


If this is true then it should be reported as a bug


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## Johan Elzenga (Dec 6, 2015)

It's not really a bug. It means Lightroom is not yet compatible with this. What Lightroom should do is kind of 'split up' the displaying. When it renders the interface items, it should indeed behave like the monitor is four times the resolution you've set. When it renders the image however, it should use the native display resolution. That it does not do (yet). If I understand it correctly, Photoshop does indeed do this, so Adobe is aware of the problem and how to tackle it.


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## Leadfoot (Dec 6, 2015)

Thanks for your response Johan and Cletus.

After looking at it  more, I agree and don't think it's a bug.  The same thing happens on a 13" retina  MBP, the Auto Preview size is always 2x the display size selected in  System->Preferences->Display.  Any sluggishness that I saw with  LR, is simply because large, 5120x2880 previews (15 Mpixel) is a lot  more data to shove around, than, for example 1920x1200 previews (2.3  Mpixel) that map directly onto a display with no scaling.  LR might  limit the preview size anyway, to 1:1.

If Photoshop can do what  you suggest - render the UI scaled, and render the image at full  resolution of the monitor - it would be great to have this in LR.


The longer story:

I  looked at the Utilities->Console->System Log, and search for  "Resolution", when I turn a display on/off, or switch resolution in  System->Preferences->Display:

Whenever the 4K display is connected (Unit 1), and it's startup resolution is NOT 4K, the Resolution is 2.
Whenever the 4K display is connected (Unit 1), and it's startup resolution is 4K (3840x2160), the Resolution is 1.
Whenever a non-4K display 1920x1200 is connected (Unit 0), the Resolution is 1.

Dec   6 04:22:52 Bob-Mac-Pro.local WindowServer[732]: Display 0x2b101c0d:  Unit 1: Startup Mode 2560 x 1440, CGSThirtytwoBitColor, Resolution 2,  ...
Dec  6 04:22:52 Bob-Mac-Pro.local WindowServer[732]: Display  0x2b3c378c: Unit 0: Startup Mode 1920 x 1200, CGSThirtytwoBitColor,  Resolution 1, ...
Dec  6 04:23:46 Bob-Mac-Pro.local  WindowServer[732]: Display 0x2b101c0d: Unit 1: Mode 3840 x 2160,  CGSThirtytwoBitColor, Resolution 1, ...
Dec  6 04:23:46  Bob-Mac-Pro.local WindowServer[732]: Display 0x2b101c0d: Unit 1: Startup  Mode 3840 x 2160, CGSThirtytwoBitColor, Resolution 1, ...
Dec  6  04:23:46 Bob-Mac-Pro.local WindowServer[732]: Display 0x2b3c378c: Unit  0: Startup Mode 1920 x 1200, CGSThirtytwoBitColor, Resolution 1, ...
Dec   6 04:24:17 Bob-Mac-Pro.local WindowServer[732]: Display 0x2b101c0d:  Unit 1: Mode 2560 x 1440, CGSThirtytwoBitColor, Resolution 2, ...
Dec   6 04:24:17 Bob-Mac-Pro.local WindowServer[732]: Display 0x2b101c0d:  Unit 1: Startup Mode 2560 x 1440, CGSThirtytwoBitColor, Resolution 2,  ...
Dec  6 04:24:17 Bob-Mac-Pro.local WindowServer[732]: Display  0x2b3c378c: Unit 0: Startup Mode 1920 x 1200, CGSThirtytwoBitColor,  Resolution 1, ...

This is the Mac OS, WindowServer's view of the display,  2560x1440, scaled by 2.  LR should be working with 5120x2880  display size, to account for the OS scaling.

It's  interesting that 2560x1440 is exactly 2/3'rds  of a 3840x2160 display, and the OS/display knows how to scale, not just  by 2 pixels, but by 1.5 pixels.  And other scaling factors.  Pretty  nifty trick by the OS/display!


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## Johan Elzenga (Dec 6, 2015)

Yeah, it's indeed a clever trick. If the OS would simply send a 2560 x 1440 pixels image to a 4K display, it would have to be *up*scaled. By using this trick, it's now *down*scaled. Anyone who has ever scaled images in Photoshop knows how different the results would be. The only problem is that the same thing now happens to the image that is displayed by Lightroom, and that is something you don't want. A complication is that your previews are too small if you made them while you were still using a non-4K display. You want Lightroom to understand that the final resolution is 4K, and use that for the images (and build previews accordingly). That's probably just a matter of time.


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## brenda degnan-kormylo (Jun 24, 2016)

I called adobe yesterday spending hours on the phone. I bought a new all in one computer with 4k monitor. it installed properly but the print in the side columns were too small. I am using lightroom 4.4. apparently this is still an issue in lr6 and also in cc. no one was able to help me. it was not a windows 10 issue but adobe issue. after continual research I found the fix and it worked. I hope this will help others out there. you do not need to upgrade your version of lightroom.
the link is this for the fix: 
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>

<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0" xmlns:asmv3="urn:schemas-microsoft-com:asm.v3">

<dependency>
  <dependentAssembly>
    <assemblyIdentity
      type="win32"
      name="Microsoft.Windows.Common-Controls"
      version="6.0.0.0" processorArchitecture="*"
      publicKeyToken="6595b64144ccf1df"
      language="*">
    </assemblyIdentity>
  </dependentAssembly>
</dependency>

<dependency>
  <dependentAssembly>
    <assemblyIdentity
      type="win32"
      name="Microsoft.VC90.CRT"
      version="9.0.21022.8"
      processorArchitecture="amd64"
      publicKeyToken="1fc8b3b9a1e18e3b">
    </assemblyIdentity>
  </dependentAssembly>
</dependency>

<trustInfo xmlns="urn:schemas-microsoft-com:asm.v3">
  <security>
    <requestedPrivileges>
      <requestedExecutionLevel
        level="asInvoker"
        uiAccess="false"/>
    </requestedPrivileges>
  </security>
</trustInfo>

<asmv3:application>
  <asmv3:windowsSettings xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">
    <ms_windowsSettings:dpiAware xmlns:ms_windowsSettings="http://schemas.microsoft.com/SMI/2005/WindowsSettings">false</ms_windowsSettings:dpiAware>
  </asmv3:windowsSettings>
</asmv3:application>

</assembly>

copy and paste this into the lightroom exe file.

for a you tube video of this through step by step instructions: https://www.youtube.com/watch?v=l4GCfugE0xQ

I hope this will help. it fixed my problem which adobe was not able to help except telling me to purchase monthly cc version.


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## clee01l (Jun 24, 2016)

brenda degnan-kormylo said:


> I hope this will help. it fixed my problem which adobe was not able to help except telling me to purchase monthly cc version.


I think it is important to realize that CS6 code is 4 years old and was developed before 4K monitors were common.   Software developers are under no obligation to update obsolete legacy software to accommodate advances in technology.  Updates to Photoshop are now found in the current CC app.  If you don't want to come a CC subscriber, this is your choice.  Adobe no longer supports a product that sold for $1500USD, but instead gives you the choice of remaining current with technology in a app that you pay for annually


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