An image processing apparatus, including a power source, an image engine, an interface to communicate with an external device and deliver power from the power source to the external device, and a controller, is provided. The controller is configured to detect connection of the external device to the interface; receive power information, including a value of regular operable power and a value of minimum operable power, from the external device; receive a job execution command; in response to receiving the job execution command, determine whether a first power value including the value of the regular operable power exceeds a value of power available for the external device during a predetermined operation by the image engine; and in response to a determination that the first power value exceeds the value of power available for the external device, control the power source to deliver the minimum operable power to the external device.