The resolution of ViewportFrames in ScreeenGuis can be reduced by stretching out the CanvasGroup size. This can result in an interesting pixelation effect, without having to use SurfaceGuis.
Here’s how to control the resolution of a ViewportFrame in a ScreenGui.
Note: Only lowering resolution of ViewportFrames is possible with this method because CanvasGroups always clips descendants.
Here’s how my setup looks:
Here, to achieve a pixelation effect across the entire screen, CanvasGroup size and VietportFrame size are inverses to each other.
CanvasGroup size:
ViewportFrame size:
In the screenshots above, I have reduced the resolution by a factor of 8.
Here’s a video of me using this method: