This article is a review of the various methods in use, Relative calibration is determined by normalizing the outputs of the detectors to a given, often average, output or under development, to calibrate space-multispectralimaging-systems in the solar-reflective range. We introfrom all the detectors in the band. The result of the normalization is that all the detectors give the same output duce the subject by distinguishing between absolute and relative calibration, briefly discussing the use of scene when the focal plane of the sensor is irradiated with a uniform-radiance field. For relative calibration, the abso-and sensor models, and describing five calibration desiderata. We then briefly describe the different types of exlute value of the radiance field need not be known. Typically the RMS variation in the adjusted normalized out-isting methods, highlighting their advantages and disadvantages, making the distinction between: preflight, puts of the detectors is in the 0.1-0.5% range, depending on the signal-to-noise ratio of the digitized output signal onboard, and vicarious calibration. The different types of radiometric calibration: absolute, multitemporal, interfrom the sensor. Relative calibration can also describe the ratio of the average outputs from two, or more, dif-band, and intersensor are mentioned with their related constraints. Finally, recommendations are made on how ferent bands of a sensor; it then is often referred to as interband calibration. A change in this ratio is indicative to improve these methods so that the scientific community may obtain remote-sensing data of the highest qualof a temporal change in response of one, or more, spectral bands. Finally, multitemporal calibration, or stability, ity. Β©Elsevier Science Inc., 1999 is determined from the ratio of the average outputs from all the bands, for the same stable scene for two different dates.