Static modulation mechanism in the case of the grey edge transmitted beam. The image shows the superposition of the square of the amplitude filter with a single Fourier component PSF (G mode). The grey edge width is indicated by two dashed grey lines on the greyscale bar. The blue (speckle 1) and red (speckle 2) expressions indicate the intensity of the speckles after application of the amplitude mask. The signal in the pupil results from the interference of the core with two speckles with an unbalanced intensity.