VIKCAL performs radiometric corrections to planetary images acquired by the Viking orbiter cameras. VIKCAL performs a radiometric correction in two steps. First, VIKCAL corrects for the varying response of the vidicon across the field of view of the camera. Multiplicative and additive correction coefficients, as a function of line and sample position, are applied to an image array to produce the results of an 'ideal' camera. VIKCAL converts the image data to radiance factor values. The radiance factor is defined as the ratio of the observed radiance and the radiance of a white screen, normal to the incident rays of the Sun.

If run on a non-spiceinited cube, this program requires access to local mission-specific SPICE kernels, in order to find the distance between the sun and the target body. When run on a spiceinited cube, this can be determined using the camera model. Using a spiceinited cube as input has the advantage of not requiring that local mission-specific kernels be available. (See spiceinit web=true.)