CORRECTION OF THE LIGHT-FALL-OFF IN PHOTOGRAPHS BY MEANS OF DIGITAL STATISTICAL METHODS

摘要

Frame camera photographs contents more information than scanner imagery due to their higher spatial resolution. Moreover their geometrical conditions are especially simple. On the other hand their great disadvantage is the light-fall-off of the objective near the image edges. This disturbance must be corrected before further digital evaluation, e. g. multispectral classification. The paper presents statistical methods for this correction: (1) low pass filtering (2) approximation by two-dimensional polynomials Results of both techniques are demonstrated and compared with the analytical cos-approach.