problem overlaying 2 textures

I'm trying to present multiple faces on-screen with a different coloured circle around each face (using Matlab 2018 with Psychtoolbox 3.0). The faces are loaded in as images, and then converted to textures. The circles are being drawn as textures using the "DrawTexture" function.

When the two are presented on-screen, the corners of the face textures are 'cutting out' parts of the circle. In the code, the circle frames are called first (using the 'Screen' and 'DrawTexture' functions), and then the faces are called the same way.

As the face images are square, the corners of the images are overlapping with the circle frames. Is there a way to ignore the corners of the images, so that the circles are not affected? From trial to trial different faces are used and they are presented in different locations on-screen, so the solution needs to take this into account

Thanks!