When referring to specs of a projector what does Trapezoid correction: 15 degrees mean?

Question

When referring to specs of a projector what does Trapezoid correction: 15 degrees mean?

Answer 1

It means the projector position can vary Left or Right up to 15 degrees + or - from center axis

>can be used/corrected 15 degrees left to 15 degrees right<,

just as Keystone refers to variation from the screen center in an up and down axis >15 degrees UP to 15 degrees Down<.

Once you exceed that correction limit

the picture will appear like a trapazoid,

ie: (left and right sides tapered in or out, or

top and bottom tapered up or down).

Answer 2

the same as keystone, it means it have keystone correction to up to 15 degrees.

http://cache.gizmodo.com/assets/resource...

http://en.wikipedia.org/wiki/Keystoning