Question about VisionEgg grating parameters

Hi All,

My name is Adam Smith, and I just recently began using VisionEgg to design stimuli for some optomotor work
I'll be doing as part of my doctoral research at the University of Maryland. I'm trying to project a basic,
symmetrical square-wave grating using the Sin2D function. However, I seem to be getting unequal widths
between my dark and light bands, and the contrast edges are much wider and softer than I would like (i.e. the
grayscale fade takes up too much of the total spatial frequency). I'm assuming the solution for this
problem is simple, but I can't seem to work it out. Given that, I figured why not ask for some help! Any
suggestions would be greatly appreciated!

I've attached my (very) basic code here as well.

Cheers,

Adam