An approach to the interpretation of the visible moiré phenomenon in the image domain has been proposed. The analysis of the Fourier series expansion presents an initial criterion for distinguishing the real moiré and pseudo-moiré cases. A geometric calculation of the superposed grating lines is utilized to obtain the parameters for describing the real and pseudo-moiré cases. On the basis of the study, the average intensities of the waveforms of the real moiré and pseudo-moiré cases are calculated in order to provide the interpretation. It indicates that different moiré cases result from the garbled discernment of human eyes, which is introduced by the microstructure versus macrostructure effects. The variations of intensity and average intensity in the microstructure result in the confusion of the average intensities of the real moiré and pseudo-moiré waveforms. The interpretation is significant for the visible real and pseudo-moiré effects, both in the multiplicative superposition and in the additive superposition composed from periodic cosinusoidal gratings and binary gratings in the image domain. The approach also considers the coexistence of the real moiré and pseudo-moiré cases. The rule for their coexistence has been summarized in the image domain.