Image sizes in slider

I am using the i-max theme and am having problems with uploaded images (including logo) re-sizing too large once uploaded. Although I re-sized the images to suggested specification (512×512) part of the image is still cut off in the slider. Can someone tell me how to fix this? The only default image left in the slider works fine, do not fit well. I am using the windows platform through Godaddy Hosting. Please advise.

http://progressivepodclip.com/wordpress/

Harlan Reece