Actually, it’s the other way around. When a user supplied a size via the shortcode, it overrides the user defined settings in the admin. The purpose is to allow the user to configure the template for multiple purposes. For example, many users use more than one template on their site and having the same image size forced upon each template doesn’t make sense so I built in the a method into the premium template to change this on demand.
Try these to force a size:
$entry->getImage( array( 'image' => 'photo', 'preset' = 'thumbnail' ) );
$entry->getImage( array( 'image' => 'photo', 'preset' = 'entry' ) );
$entry->getImage( array( 'image' => 'photo', 'preset' = 'profile' ) );
$entry->getImage( array( 'image' => 'logo' ) );
The preset option explained:
thumbnail = the small image settings
entry = the medium image settings
profile = the large image settings
The image size will be that of the settings applied to the image at the time of upload. The preset names don’t match the actual naming in the settings because I decided after writing the function that it made more sense to present the users as the choices small, medium and large.