1. A method for generation of a background mask from an intensity-value-coded image having a noisy background area, comprising: generating an intensity value histogram of the image; fitting a model curve to a subarea of the intensity value histogram; calculating a threshold value in the intensity value histogram from the fit parameters of the model curve; and generating the background mask starting from at least one defined image area that belongs to the background noise by adding all the pixels, whose intensities are below the threshold value, to the background mask when connected to the image area via pixels whose intensities are also below the threshold value.