Image upscaling factor (found in Render Setup > System > System settings > Interactive rendering) lowers interactive rendering resolution, and then up-scales it back to the specified resolution. This results in:
- Faster interactive rendering
- More responsive interactive rendering
- The on-screen dimensions of the interactive rendering VFB being unaffected
- The resolution of the rendered image being lower
- Pixels of the rendered image being larger ("pixelated" appearance)
This is especially useful on High-DPI monitors (e.g. with 4k or higher resolution), where interactive rendering may be running in very high resolution, which may affect rendering performance.
Note: This does not affect regular (non-interactive) rendering in any way.
Examples
Image upscaling set to the default value of 1. In this case, it has no effect (image upscaling is disabled):
Image upscaling set to 2. Each pixel is 4 times larger:
Image upscaling set to 4. Each pixel is 8 times larger: