Contrast vs opacity using gabor

[Michael]

I don’t really understand this stuff, but is this thread relevant?

ElementArray of gratings with non-zero pedestal value

Hi all, I would like to draw a number of gratings on a background that is darker than 0 (in Psychopy’s [-1, 1] convention) luminance. I need to be able to manipulate the contrast of these gratings from trial to trial. I want the mean luminance to be constant across the window, so the contrast needs to change the span of the grating luminance around the background value (pedestal) My understanding is that this is not currently possible out of the box in Psychopy. I’ve found some discussion of a…