Both the phase and the amplitude spectrum may determine the appearance of natural images.

Several studies have demonstrated that the appearance of a natural image is determined mostly by its global phase spectrum; the amplitude spectrum is regarded as providing little specific information. In this paper, we show several cases where the global amplitude spectrum is also essential for specifying the particular content of natural images. Thus, both the amplitude and the phase spectrum may be important for reliable specification of such images. The results suggest that, although the average amplitude spectra of different natural images may be similar in their overall form, a realistic description of the amplitude spectra must also incorporate the particular way in which the energy is distributed across different orientations.