Polychromatic imaging method in the observation spectral band of 360 nm to 950 nm, comprising the following steps: /1/ carrying an image-capturing optical system on board an aircraft or spacecraft, said image-capturing optical system comprising a telescope and being adapted to form views in at least one focal plane, respectively based on radiation within several spectral sub-bands each contained within the observation spectral band; /2/ placing at least one array (2 1,..., 2 n) of photodetectors in said at least one focal plane, in order to capture an intermediate image of each view formed by the image-capturing optical system at a resolution associated with said intermediate image; /3/ capturing the intermediate images of a same scene respectively for each spectral sub-band; and /4/ merging the intermediate images captured respectively for the spectral sub-bands, in order to form a final polychromatic image, the telescope of the image-sensing optical system determining a pupil which is common to the spectral sub-bands, and a dimension of said common pupil setting a spatial cutoff frequency which is different for each spectral sub-band, the spectral sub-bands comprising a first spectral sub-band and at least one other spectral sub-band extending towards the large wavelengths, with said other spectral sub-band extending towards the large wavelengths having at least one wavelength larger than an upper limit of said first spectral subband, the pupil of the telescope being sized so that the spatial cutoff frequency for the first spectral sub-band is greater than the Nyquist frequency of the intermediate image captured for said first spectral sub-band, each spectral sub-band being determined by a single filter (3a-3d) which is effective for all the photodetectors used for capturing the corresponding intermediate image, by extending continuously between points of the view of concern which are imaged on these photodetectors, the method being characterized by the pupil of the telescope additionally being sized so that the spatial cutoff frequency for said other spectral sub-band extending towards the large wavelengths, is less than the Nyquist frequency of the intermediate image captured for said first spectral sub-band, and in that the intermediate image captured for the first spectral sub-band is formed using a sampling pitch (p b) for the corresponding view which is two times smaller than another sampling pitch (p d) used to capture the intermediate image for the other spectral sub-band extending towards the large wavelengths, said sampling pitches being measured parallel to the rows (L DET) and columns (C DET) of photodetectors, so that the sampling for said first spectral sub-band corresponds to a surface density four times greater than in the sampling for said other spectral sub-band extending towards the large wavelengths. /1/ carrying an image-capturing optical system on board an aircraft or spacecraft, said image-capturing optical system comprising a telescope and being adapted to form views in at least one focal plane, respectively based on radiation within several spectral sub-bands each contained within the observation spectral band; /2/ placing at least one array (2 1,..., 2 n) of photodetectors in said at least one focal plane, in order to capture an intermediate image of each view formed by the image-capturing optical system at a resolution associated with said intermediate image; /3/ capturing the intermediate images of a same scene respectively for each spectral sub-band; and /4/ merging the intermediate images captured respectively for the spectral sub-bands, in order to form a final polychromatic image,