1. A method for detecting fog by use of a camera image or a video image, the method comprising the acts of: taking a two-dimensional image with at least one color channel or several color channels as a function of two independent location coordinates; determining a two-dimensional gray-scale function for the at least one color channel or for each of the several color channels, which defines a value of the gray scale as a function of the two independent location coordinates of the two-dimensional image; performing a two-dimensional Fourier transformation of the two-dimensional gray-scale function depending on two independent frequency coordinates; scaling the two-dimensional gray-scale image to compensate intensity gradients of the gray scales by use of a low-pass filter and by use of a high-pass filter; calculating a power spectrum as the square of the absolute value of the Fourier transform; analyzing the power spectrum by use of digital image processing; analyzing the power spectrum by use of a family of Gabor filters; filtering the power spectrum by each Gabor filter of the family of Gabor filters over the two-dimensional frequency range, wherein a result of said filtering is a Gabor characteristic for each of the corresponding Gabor filters; and reducing the Gabor characteristics by one of a main component analysis or a support vector method in the frequency domain to form reduced Gabor characteristics.