Different authors have studied the response of the human visual system (HVS) in the chromatic frequency domain and have obtained its spectral modulation sensitivity function (SMSF), either computationally or experimentally. The Fourier analysis applied to the colour signals (product of the spectral power distribution of the illuminant and the reflectance or transmittance function of an object) carries out the chromatic frequency domain. The SMSF defined in this domain is analogous to the CSF or the TMTF, which are defined in the spatial and temporal domains, respectively. We have studied how HVS processes chromatic information of daylight and natural objects. The analysis of the original and filtered colour signal with different cut-off frequencies reveals some degree of degradation of these colour signals. This is particularly important when the colour signal are characterised by peaked spectral power distributions.