Wigner-space diagrams as well as amplitude and phase images of a wave field throughout the lensless imaging process. ν is the bandwidth of the signal, while x is its lateral extent. a) Amplitude of wave field U _O in the object plane, its support in phase space defines the space bandwidth-product (SBP) of the wave field. b) Phase of propagated wave field U _H , the central box represents the SBP of a camera sensor. The propagation shears the support in phase space. High frequencies are recorded as badly sampled alias frequencies. c) Phase of propagated spherical reference wave R. d) Phase of the measured cross term M = U · R*, the spherical reference wave aligns the SBP of the coherence function and the sensor.