Understanding screen resolution / scaling

Question

Hi all,

New windows user here Coming from Mac I'm trying to figure out the resolution\scaling effect. I have a XPS 15 with 4k display and it's set by default to full resolution and 250% scaling (which I reduced to 225%). I was wondering what would be the difference if I reduce the resolution to something smaller (e.g. 2560 x 1600) and change the scaling accordingly. I read somewhere that it doesn't really change the real resolution. Is it true? The reason I'm asking is that for some games (RDR2) I have to close all applications, manually reduce the resolution in display settings and after I'm done change the resolution back and re-launch all applications (to avoid window size changes). It's really annoying ...

Thanks in advance

Haim

jphughan · Accepted Answer

@babysnakes That would look worse. When you’re running at the native resolution, then Windows is still rendering at the native resolution of the display, and then in terms of scaling, vector assets that can scale with zero loss in quality (like text) don’t suffer any scaling effects — as long as the application is coded to implement scaling properly, which admittedly isn’t always the case. But if you switch to 2560x1600, then Windows isn’t even rendering for the native resolution of the display anymore. Instead, it renders for 2560x1600 and then either the display itself or the GPU (depending on hardware and settings) will take that rendered image and scale it up to the native resolution of the display. The problem there is that a 2560x1600 rendered image does not map cleanly onto a 3840x2400 pixel grid, so EVERYTHING will look a bit worse. The only exception here is that if you have some application that handles scaling horribly, then running your display at a lower resolution and using 100% scaling might look better overall — but that’s a specific case, and it doesn’t sound like you’d be planning to run a resolution low enough to make 100% scaling possible anyway.

The thing you may have read about changing the resolution not really changing the resolution may have been a post of mine. That has to do with the distinction between the desktop resolution and the active signal resolution. Essentially, depending on your hardware and GPU, when you run a resolution below the display’s native resolution, one implementation is for the render work to be done at that lower resolution and then for the GPU to scale up the rendered image to the native resolution of the display, so that the signal actually on the wire is still the display‘s native resolution, rather than the display having to do the scaling. But the question of whether the scaling would be done in the GPU or the display wouldn’t change the problem I just described. 2560x1600 doesn’t map cleanly onto 3840x2400 pixels, no matter where that scaling occurs.

Does RDR2 really not allow you to choose a custom resolution within the game? Most games do.

babysnakes · Answer

Thanks for the detailed explanation, much appreciated.

The problem with RDR2 is that I can't play in native resolution (not enough GPU RAM) and otherwise it will not play full screen. I don't think I tried 1920x1200 (half my resolution) without changing the actual resolution - maybe it'll map better and allow full screen.

jphughan · Answer

@babysnakes Hmm, I haven't played RDR2 on PC, but I'm surprised to hear that you have to choose between native resolution or windowed gaming. The game really doesn't offer an option to run full screen at a lower than native resolution? That is VERY unusual for a game. Are you absolutely sure about that? It just sounds hugely odd, because a game like RDR2 would be very graphics-intensive, so MANY systems today would be unable to run it acceptably at their display's native resolution, and therefore there would be a lot of demand to run at a lower resolution but still main full screen.

But yes, 1920x1200 should look much better since in that case each rendered pixel maps precisely onto a 2x2 physical pixel. (It's actually 25% of native since it's half the resolution in each dimension.)

babysnakes · Answer

Well, It does offer a fullscreen option but it does't show in full screen, just a borderless window. Only when I match the exact resolution does it play fullscreen. Searching the internet I was certainly not the only one with this problem (this is how I found the idea to match resolutions) but there were also references to make sure I'm running with DX12 (which I don't have any idea how to check ). Since it's my second week on windows It's very possible that I'm missing something.

In any case, trying half resolution didn't work either.

jphughan · Answer

@babysnakes  Especially given that others are reporting this issue, this sounds like it may be some sort of RDR2 bug. Checking whether you’re using DX12 would have to be using some mechanism provided by the game, but it is overwhelmingly likely that you are, since DirectX is far more widely used on Windows for game rendering than the alternative, namely OpenGL. Sorry I don’t have any further suggestions though!

babysnakes · Answer

Thanks a lot for your patience. Your first answer was the info I was looking for

XPS

Understanding screen resolution / scaling

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