When Aizen created his army of arrancar in Hueco Mundo, Ichigo is taught to control his inner hollow by the Visored, Soul Reapers with hollow powers. This allowed him to call upon his hollow powers at will without sacrificing control by donning a hollow mask through a limited time. Although Ichigo and his friends managed to fend off the arrancar with bolstered defenses, they are unable to prevent the abduction of Inoue Orihime.
I must be getting old… but anyway! Thanks to Jose for sending this amazing shot and be sure to check out the full version!