Kugiigi, I get what you mean. I’m not trying to expand the screen beyond the physical limit, but reduce the screen at the opposite side where it is wider, instead of reducing the screen at the side where it is already narrower. You get what I mean?
When the projector is tilted on the wall, the upper screen will be wider, so keystone correction to reduce the width at the upper screen make sense.
However, when the projector is tilted on the ceiling, the upper screen will be narrow. So the keystone correction to reduce the width at the upper screen simply make it worse off.
How do I reduce the width at the bottom screen instead?