How to make circular slideshow carousel?

Hello,
I'd like to make the slideshow pictures in the shape of a circle.
I'm using the Slideshow CK carousel - Menu theme: default - Joomla 3.6.2

I can't find a place where I can specify the width of the picture.
I already tried in the Image styles to make the rounded corners bigger, but it doesn't help much.
I just want a carousel of circles without text (I managed to turn off the description options) instead of rectangles.

Is it possible to do so?
My site is local, so can't show you, but I add a screenshot.

Any help would be appreciated
Regards

Hi
what is the relation between "a place where I can specify the width of the picture" and "pictures in the shape of a circle."
the width/dimensions have to be set in the styles options of the module

for the rounded corners, you can add this rule
CEd