Patent ID: 7373131

Claim:
A signal processing method comprising: a first frequency conversion step in which processing is performed to convert a frequency of an input signal with a first periodic signal having a predetermined frequency; a second frequency conversion step in which processing is performed to convert a frequency of the input signal with a second periodic signal having a predetermined frequency; a phase delaying step in which processing is performed to increase a phase difference between a signal converted in the first frequency conversion step and a signal converted in the second frequency conversion step by π/2; and an adding step in which processing is performed to output a sum signal of respective signals where the phase difference between said signals converted in the first and the second conversion steps has been increased in said phase delaying step; wherein the signal processing method comprises: a subtracting step in which processing is performed to output a subtracted signal which is a difference between said respective signals; and a signal processing step in which processing is performed, assuming either one signal of the sum signal or the subtracted signal is a first signal and another signal is a second signal, to remove a component of an image signal included in the second signal, using a correlation between the first signal and the second signal and using the first signal.