Image processing apparatus and method for processing an image with secure job interruption

An image processing apparatus performs authentication of users. A first and second user inputs first and second user information, respectively, through an input section. A controller controls the authentication section to perform first authentication of the first user information, and controls the job execution section to execute the first job if the first authentication is successful. The controller controls the job execution section to halt execution of the first job upon an interrupt by the second user, and to execute the second job when the first job remains interrupted. A memory stores interrupt information indicative of a status of execution of the first job when the interrupt occurs. The controller controls the authentication section to perform second authentication of the first user information after the second job has been completed, and then controls the job execution section to resume execution of the first job if the second authentication is successful.