This study, describes a novel method for characterizing the colorimetric and photometric properties of three-channel color imaging devices. The method is designed to overcome some undocumented aspects of the imager-characterization problem: The effective spectral sensitivity profiles of the imager's color channels depend on the level of radiant input energy, and these profiles must be known in order to determine the true intensity response characteristics of the three channels. By fitting the response distributions of the three color channels explicitly with low-dimensional models, the method takes these dependencies into account, and may, therefore, offer several advantages over other imager-characterization methodologies, particularly where illuminant-independent characterization is required. An application of the technique is detailed, in which a CCD camera is characterized using only the Macbeth ColorChecker and a number of artificial illuminants.