BONKERS
Member
I think you're misunderstanding. 0.5x SSAA basically means the game will render at half of whatever resolution you actually have selected. So with 0.5x SSAA selected, 1920x1080 becomes 960x540. That's the reason why there is no 1xSSAA, because that would just be whatever resolution you picked. 2xSSAA is the game rendering your resoluion at twice the size then fittting it to the screen so that it looks better, and so on for 3x and 4x.
Edit: Simply put, 0.5x SSAA will look worse than having no SSAA. Unless you want better performance, you should NOT use 0.5x SSAA.
It's actually the amount of pixels. 960x540 is actualy 0.25x 1080p. (One quarter the amount of pixels. Hence why 960x544 is referred to as Quarter full HD or some stupid jazz).
Half as much resolution of 1920x1080 is actually in the neighborhood of ~ 1360x765
Twice as much resolution (2xSSAA)is actually usually ~2.25x (IE 1280x720 to 1920x1080) or it can also be increasing one axis over the other. (IE: 2x1 or 1x2. This would be an even 2)
And so 4xSSAA is actually 2x2 your resolution. (2x2=4)
(So 1920x1080 + 4xSSAA = render at 3840x2160>Downsample)