Cross-correlation of the modulated signal of a noiseless point source located at [−100, 0] mas with the transmission map. Left: cross-correlation at a single wavelength. The resulting image can be understood as the demodulated signal function of such a point source at the considered wavelength. The image is antisymmetric with respect to the image center. Right: combined cross-correlation across the full wavelength range considered for the ideal point source. Considering a broader wavelength range reduces the side lobes and allows for a better location of the point source.