is there a way to "scale" them?
Yes, by changing the monitor's dpi (ppi). For example if one screen is 24" and the other is 21" with the same resolution then the smaller one has 12.5% higher dpi, just set its dpi to ~112.5%
But in reality it's not simple as that. Previously all monitors are supposed to have the same dpi. That means you're out of luck if you use older Windows versions
However Windows 8.1 introduced the ability to have different dpi's, so you can have setups like two full HD monitors, one 18" at 150% dpi and the other 24" at 100% dpi and having things shown at the same size
That said, the support was very sketchy, because it's the first time ever Windows has per-monitor dpi settings. A program opening on a monitor will inherit that monitor's DPI. And when moving to another monitor it'll be scaled up/down depending on the dpi instead of being notified about dpi change, so the result will be worse (blurrier or sharpener)
Since then, MS has announced Per-Monitor V2 in Windows 10 1703 which are much better at handling hidpi displays
In conclusion, you need at least Windows 8.1 for this to work
Below is the summary of dpi support in Windows
DPI Awareness Mode |
Windows Version Introduced |
Application's view of DPI |
Behavior on DPI change |
Unaware |
N/A |
All displays are 96 DPI |
Bitmap-stretching (blurry) |
System |
Vista |
All displays have the same DPI (the DPI of the primary display at the time the current user session was started) Bitmap-stretching (blurry) |
|
Per-Monitor |
8.1 |
The DPI of the display that the application window is primarily located on |
• Top-level HWND is notified of DPI change • No DPI scaling of any UI elements. |
Per-Monitor V2 |
Windows 10 Creators Update (1703) |
The DPI of the display that the application window is primarily located on |
• Top-level and child HWNDs are notified of DPI change • Automatic DPI scaling of: • Non-client area • Theme-drawn bitmaps in common controls (comctl32 V6) • Dialogs (CreateDialog) |
High DPI Desktop Application Development on Windows
See also