A method to generate a security pattern to be embedded in an original image has the particularity that the detection of the security pattern can be achieved through a simple, low processing capability device. The method for generating a security image comprising the original image and the security pattern is characterized in that the security pattern is formed by an inverse transform of the combination in the frequency domain of an auxiliary image and a radially symmetric, two-dimensional pattern, said two-dimensional pattern created by sweeping a self-similar, one-dimensional function along a 360-degree arc, and the security image is generated by the modulation of at least one color of at least a part of the original image with the pattern.