The present disclosure relates to a signal processing device, a signal processing method, and a signal processing program which can more accurately perform color reproduction to an image captured by using visible light and infrared light.A plurality of pixel signals, output by a color-difference sequential system from an image sensor on which light having passed through a color filter array including a plurality of complementary color filters is incident, are acquired. With respect to the plurality of pixel signals, a parameter to eliminate a term corresponding to a predetermined infrared wavelength in an equation to calculate a color-difference signal from the plurality of pixel signals, is set using the plurality of pixel signals. Thereafter, a luminance signal obtained by performing an addition process of the plurality of pixel signals and a color-difference signal obtained by performing a subtraction process between the plurality of pixel signals are calculated using the parameter.