1. A method for processing image data comprising: taking with a camera a first sequence of n images of an object with different exposures wherein the object and the camera remain static with respect to each other, wherein the sequence contains one reference image with pixel values and n−1 further images with n≧2, the reference image and the further images having pixels, wherein each pixel has a pixel value; calculating for each pixel value of the reference image n−1 arrays containing x difference values, each of the n−1 arrays corresponding to one of the n−1 further images, wherein x is the number of times a considered pixel value appears in the reference image; calculating n−1 mean difference curves, each mean difference curve representing a mean difference value for each pixel value for each of the n−1 further images; and storing the mean difference values represented by the mean difference curve for each pixel value and for each of the n−1 further images in a look-up table.