Two dimensional Fourier analysis of the earth gravitational field using the program package TIM

The program package TIM for image processing was used for spectral analysis, in particular of the earth gravitational field. Fourier analysis using TIM is described. The multiplication and scaling factors have to be handled very carefully to calculate the results back to real life values. Rounding off errors always remain . Filtering in the frequency domain introduces complexity and makes the final results less precise. The main conclusion of this study is negative with respect to the Fourier transformation performances of TIM. A positive conclusion is that TIM is very well suited for representation purposes.