Our themes uses several different image sizes which are listed below:
Revolution Slider - 1920 x 550 (can vary if you use different Slider size)
Blog - 800 x 490
Portfolio - 700x600
These are the general sizes used. Different sections of the Theme uses different croping. To change it, open functions.php and at the top you will notice code like:
add_image_size( 'homePort', 393 ,300, true );
After you change the size of the image, you need to regenerate Thumbs for the changes to be visible.