posterboard view image size issue

i am using the posterboard view for an events page, and i see it pulls the images from the featured image on the event.

i am also using my events in a the genesis responsive slider, which requires a different sizing for my featured images.

i am wondering if i can find a way to have my posterboard view look better…

http://www.emilyperryyoga.com/events

https://wordpress.org/plugins/all-in-one-event-calendar/