1. A method of determining a laundry load size in a laundry treating appliance comprising a rotatable drum at least partially defining a treating chamber for receiving laundry for treatment in accordance with a treating cycle of operation, an imaging device, and a controller having a processor, the method comprising: generating an image, with the imaging device, of a portion of the treating chamber where the treating chamber has detectable graduated markings located on a solid portion of the drum; detecting, by the controller, at least one of the detectable graduated markings in the generated image; and determining, by the controller, a load size based on the detected at least one of the detectable graduated marking, wherein the determining the load size comprises counting the detected graduated markings and comparing to a reference value that indicates a free volume.