Scaling windowed games to full screen using state-of-the-art spatial scaling algorithms, sharpening algorithms and machine learning.
Example screenshot ^^^. You don't need to copy these settings exactly. It's easy/quick to experiment for the best settings for you. The 1.8x scaling is for my high res monitor, yours will probably need less.
Update: Sept 21 2022. There is no more free demo version. Use Magpie or IntegerScaler if you don't want to pay (this costs $5.69 USD).
New alternative to IntegerScaler with Windowed Mode Scaling, Full Screen and easier setup than IntegerScaler. No computer skills needed. Better Multi-Screen support than IntegerScaler but not as good as Magpie. For multi-monitor setups I recommend Magpie if you'll be playing in fullscreen.
This program allows Full Screen or Windowed mode resizing (any size 1.0x or larger). Several smart resizing renderers available ("LS1" type uses machine learning upscaling) so any size looks crisp, almost like a new HD-remastered client. Perfect multi-monitor support: You can move the PWO window around freely and it behaves just like any standard window. Unlike IntegerScaler you can have PWO fullscreened on either screen, not just on your primary monitor.
Another benefit of this app is you can stretch to True Fullscreen ignoring aspect ratio, so there's no black bars like in IntegerScaler. Magpie can do this too (use 'Fill' mode instead of 'Fit')
Overall this is a great app but only worth the $5 over Magpie (which is free) if you care about Window Mode (playing PWO in a bigger window). Or if you need the few extra FPS (frames per second) or slightly better image quality (LS1 algo in "performance" mode from this app is the best quality/performance ratio you can get for PWO). LS is also slightly easier to set up/use.
-When returning mouse focus to PWO from other screen, my cursor randomly jumps a short distance. To overcome this use Magpie instead.