An imaging device receives from a host image data and commands including a normal command and a real-time command to be processed prior to the normal command. A receiver receives a real-time processing disable command with a parameter indicating a number of bytes of the image data, and a processor processes the image data in terms of the number of bytes without processing the real-time command, after processing the real-time processing disable command. In a method for so controlling an imaging device, the host controls transmission of image data and commands including normal and real-time commands to an imaging device as noted above. The host comprises a detector that determines if data to be transmitted includes image data, and a processor that transmits the image data after transmitting a real-time processing disable command with the parameter described above, if the detector determines that the data includes the image data.