To provide a signal processing apparatus and an image pickup signal
processing method both of which restrain a color signal from being
influenced by band limitation in a color processing system, thereby
enabling signal processing which produces an undegraded image, the
processing of color-suppressing RGB signals or complementary color
signals is performed between a color interpolation circuit and a
color-difference matrix circuit. Otherwise, the processing of suppressing
a color signal is performed in front of the color interpolation circuit.