IMAGE PROCESSING APPARATUS WORKING IN RESPONSE TO FREQUENCY DIFFUSED CLOCK AS REFERENCE TO PROCESS INPUT IMAGE SIGNALS

A system clock generation module varies an oscillation frequency and outputs a frequency diffused clock as a system clock. A synchronizing signal measurement module measures a synchronizing signal characteristic value, which includes at least a synchronizing signal period and a synchronizing signal cycle corresponding to an input image signal, relative to a measurement clock generated from the system clock as a reference. An image signal analyzing module determines that specification of the input image signal is changed when the observed synchronizing signal characteristic value is out of a predetermined range, while determining that the specification of the input image signal is unchanged when the observed synchronizing signal characteristic value is in the predetermined range. The image signal analyzing module analyzes the input image signal according to a result of the determination. This arrangement of the present invention ensures stable analysis of the specification of the input image signal.