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 IntegerScaler if you don't want to pay (this costs $5.69 USD).
New alternative to IntegerScaler with better Multi-Screen support, Windowed Mode Scaling and easier setup. No computer skills needed.
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.
For touchscreen users, Lossless Scaling handles PWO better in fullscreen. Touch still doesn't work on main buttons, but IntegerScaler returns to Window mode while LS retains FS with accidental screenpress.
Well worth the $5 for paid version. Highly recommended.
-When returning mouse focus to PWO from other screen, my cursor randomly jumps a short distance.