Converting DN value to reflectance directly by relative radiometric normalization

An automatic algorithm for relative radiometric normalization is presented. It directly normalizes the digital numbers (DN) of images band-by-band to surface reflectance. A united linear relationship from DN of target images to surface reflectance of reference images is derived and the applicable conditions are given. The iteratively re-weighted multivariate alteration detection (IR-MAD) transformation is used to select pseudo-invariant features (PIFs) automatically. The procedure is simple, fast and completely automatic. The algorithm is applied to normalize two Landsat TM images, and the result is satisfactory in both accuracy and consistency.