Heat treatment of metallized compound semiconductors results in generation of Ohmic contacts. The morphology changes of the surface during the thermal treatment can be observed by scanning electron microscope. According to our previous results these patterns show fractal character. The fractal dimension of a self-similar object can be calculated using the toolbox of fast wavelet-transform. A method is presented for analyzing the electron microscopic images of the heat treated samples by a fast wavelet-transform based algorithm using the filter coefficients of the two dimensional B-Spline functions. A connection between the dimension values of the patterns and the temperatures of the heat treating are shown.