Screen size not corresponding

[Gunroar:Cannon()]

A few issues...

1) Love says my screen res is 1280x720 (using love.graphics)
2) I just found out recently my screen res is actually 1280x800, why the 720?
3) I drew a 1280x800 image over a screenshot of my project, but when I use the image it doesn't align. It aligns horizontally but the vertical is messed up.

Possible causes/fixes?

[gcmartijn]

Maybe

https://love2d.org/wiki/love.graphics.g ... Dimensions

[Gunroar:Cannon()]

I still don't understand though, shouldn't an image the same size as the screen (let's say a not fully opaque screenshot) match all the elements in the game? just by drawing it at position 0,0 with no change to scale or anything?