This paper describes a computer program, called ATCOR, which is used to correct signatures obtained from LANDSAT data for differences in sun angle, haze level, and background reflectance.
A set of pre-computed tables is used in the calculations. These tables give the response of the LANDSAT multispectral scanner in each channel as a function of the solar zenith angle, 9, the atmospheric haze level, T, the target reflectance, R, and the average background reflectance RB. The tables also provide coefficients a and b such that for fixed, 9, r, and R the sensor response in a particular channel is given by
C = αR + b.
The minimum value method is used to determine T and RB is determined by averaging over the data. Appropriate a and b coefficients are then looked up in the tables. In most applications the signatures from a given segment (the training segment) are corrected to correspond to the same v values of 9, T, and R as some other segment. This is done by determining the a and b coefficients for each segment independently. From these coefficients the transformation is determined which corrects the training segment statistics.
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