Calibration for true color is available through absolute spectroradiometric calibration at each of 17 different wavelengths. This allows the 12-bit data in each wavelength to be used in conjunction with a calibration of the display medium to present an approximation to the absolute spectral radiance of Mars.
Devon G. Crowe, Peter H. Smith, "Calibration of the Imager for Mars Pathfinder (IMP)" in Proc. IS&T 3rd Color and Imaging Conf., 1995, pp 172 - 173, https://doi.org/10.2352/CIC.1995.3.1.art00045