Display driver, operating method thereof, host for controlling the display driver, and system having the display driver and the host

An image processing system comprising:

• a display driver;
• and
• a host configured to control an operation of the display driver, the display driver configured to generate a count value by counting a period of a synchronization signal related to a synchronization packet transmitted from the host, receive a first mode change command, which indicates a change from a video mode transmitting first image data to a display by bypassing a frame memory to a command mode transmitting second image data to the display through the frame memory, from the host, and generate an internal synchronization signal having a period substantially equal to the period of the synchronization signal by using the count value after a last pulse of the synchronization signal is generated, and a time interval between the last pulse and a first pulse of the internal synchronization signal is equal to the period of the synchronization signal, and the host does not transmit a new synchronization packet to the display driver after the video mode is changed into the command mode.