Abstract: An image is decomposed into a multifrequency channel representation by means of a set of Fourier transformation or discrete consine tra nsformation(DCT) base. We got the data of the image on the frequency space, and transformed these modulus so as to realize the obscurity of the image’s data. F rom the results, we have found out that such obscurity of information is obscure and puzzling to aggressors.

Key words: Fourier transformation, fast Fourier transformation, discrete consine transformation, butterfly arithmetic, image energy