External monitor and DPI

[VectraMan]

I currently have an old 1366x768 15" laptop with a 21" 1080p screen attached. This works out quite well as the pixel size is roughly the same between the two. I've been looking at new laptops and quite a few come with QHD screens, but that means using a higher DPI to make text readable which will then make the text on the external monitor far too large.

From what I've Googled, Windows 7 has no solution to this, Windows 8.1 has a solution that doesn't work very well, and Windows 10 does it properly - "almost as good as OSX". Though how much this depends on applications supporting a particular API I don't know.

Before I spend the money does anyone have experience of this, and how well does it work in reality?

[VectraMan]

Bump. Is no-one here doing this? Should I ask my accountant?

[NotAllThere]

I don't really understand the question. I plug my laptop into a docking station and set the screens accordingly. I have the laptop screen at 1366x768, screen 2 at 1920x1080 and screen 3 at 1280x1024. All works nicely (windows 7).

Or are you replicating the laptop screen to your monitor?

[VectraMan]

I mean what if the laptop screen is much higher resolution - i.e. 3200x2160 (or whatever they are)? That's going to make the text unreadable with standard settings, so you have to increase the DPI, which then means the text is too large on an external second monitor, unless it also has a QHD resolution. Even a 1080p 15" laptop is going to be hard to read without increasing the DPI.

All the high end laptops are pushing the QHD / Retina displays, but does this make them unusable with external second monitors? That is the question.

[WTFH]

I mean what if the laptop screen is much higher resolution - i.e. 3200x2160 (or whatever they are)? That's going to make the text unreadable with standard settings, so you have to increase the DPI, which then means the text is too large on an external second monitor, unless it also has a QHD resolution. Even a 1080p 15" laptop is going to be hard to read without increasing the DPI.

All the high end laptops are pushing the QHD / Retina displays, but does this make them unusable with external second monitors? That is the question.

You go into the settings on the laptop and adjust each display to suit.


Your limitations are:
1. The graphics card capability of the laptop
2. Each individual screen resolution.


(I've just tested this by dropping my monitor down to 800x600 while running the laptop at 1600x900. Both displayed at their respective resolutions/sizes.)


If you want the text to remain the same size on both screens then you drop the res of the laptop when it's connected to an external.

[VectraMan]

You go into the settings on the laptop and adjust each display to suit.

Your limitations are:
1. The graphics card capability of the laptop
2. Each individual screen resolution.


(I've just tested this by dropping my monitor down to 800x600 while running the laptop at 1600x900. Both displayed at their respective resolutions/sizes.)

If you want the text to remain the same size on both screens then you drop the res of the laptop when it's connected to an external.

Which is a crap solution as you lose the benefit of the higher resolution display and if you can't get exactly half resolution it'll be doing an irregular stretch which looks terrible on LCD displays.

[NotAllThere]

I mean what if the laptop screen is much higher resolution - i.e. 3200x2160 (or whatever they are)? That's going to make the text unreadable with standard settings, ...

[WTFH]

Which is a crap solution as you lose the benefit of the higher resolution display and if you can't get exactly half resolution it'll be doing an irregular stretch which looks terrible on LCD displays.

OK, so if you want to keep both displays at their maximum (and the graphics card can cope), then do so, but you'll have differing "sizes" of text. You cannae change the laws of physics.


As for the "irregular stretch", again, your graphics card should cope with that based on how you set it up. The text will not be stretched. If a character is 10 pixels high by 10 pixels wide on one screen, it will be 10 pixels high and 10 pixels wide on another screen, irrespective of screen resolution. If one screen has a different ratio to the other (e.g. one is 16:9 and the other is 4:3) then the results will depend on your graphics card. Either one screen will be displaying more vertical information than the other, or you will have black bars on one screen to mimic the ratio of the other.


Let's say a character is 10px square and screen 1 is 3200x1800. You will get 320 characters across the width of that screen. Screen 2 is 1600x1200. You'll get 160 characters across it. That's using both screens at their maximum resolution.


So, now you tell me that screen 1 is 15" and screen 2 is 31"
1. 15" diagonal = 32cm width (roughly). That means each of the 320 characters will take up 1mm of space.
2. 31" diagonal = 64cm width (ish). That means each of the 160 characters will take up 4mm of space.
Physical size difference is x4 due to the screen size and pixel size.


Back to what I said earlier - if you want to change the text to be the same physical size on the two screens then you need to adjust one screen to suit the other. In the above example, that would mean dropping the laptop to 800x450, or upscaling the text on the laptop (if the graphics card supports independent upscaling)

[VectraMan]

OK, so if you want to keep both displays at their maximum (and the graphics card can cope), then do so, but you'll have differing "sizes" of text. You cannae change the laws of physics.

Actually you can change the laws of physics. In this case anyway as the program running on one monitor can increase the size of its fonts based on the system DPI setting for that monitor. Also it seems under Windows 8.1/10 the system scales the output of a non-compliant application to suit the monitor it's running on.

Read all about it:

https://msdn.microsoft.com/en-US/library/dn469266.aspx

What I was trying to find out is if anyone is doing this in practice and can confirm how well it works. Obviously I'm just going to have to buy the thing and try it.

As for the "irregular stretch", again, your graphics card should cope with that based on how you set it up. The text will not be stretched.

Nothing to do with that. If you have a 1920x1080p LCD panel and you put it in 800x600 mode it's going to look crap as the pixels from the output don't correspond to the physical pixels in the panel. This is how it's always been with LCD. Text is stretched, because everything is stretched because the OS thinks it's in 800x600.

[WTFH]

Nothing to do with that. If you have a 1920x1080p LCD panel and you put it in 800x600 mode it's going to look crap as the pixels from the output don't correspond to the physical pixels in the panel. This is how it's always been with LCD. Text is stretched, because everything is stretched because the OS thinks it's in 800x600.

Right now my laptop is running at it's recommend 1600x900 (16x9)
My monitor is running at 1680x1050 (16x10)
So, you might say I won't see the difference between 1600 and 1680. I'll drop the monitor down to 1440x900. No stretching.
Next test - drop the laptop from 1600x900 to 1440x900 (i.e. change the ration from 16:9 to 16:10) - laptop now has black bars down either side. It does NOT stretch the output to fit the panel.


Check your graphics card settings.


(running Win7 on an Lenovo laptop with Intel graphics)