Gaze-contingent window with smooth edge and background image

Dear PsyhoPy users,

I’m trying to program an eyetracking experiment using a gaze-contingent moving window (i.e., a small circular area revealing part of an image and being moved around using one’s gaze). I have a working demo from the SR research website (the company providing the eyetracker I use).

My problem is that I can’t figure out how to make the edge of the moving window blurry (to reduce the contrast between the window and the background). Specifically, the demo I use applies a visual.Aperture to a (foreground) image. Additionally, I present a background image that is not affected by the aperture.

The aperture method doesn’t seem to contain a feature to make its outline smooth or blur with the background. Other approaches I tried did not seem to work as intended either (my problem is that I can’t use a mask that covers up the background image).

Any pointers to relevant demos or ideas how to approach this problem would be appreciated!