1. A method of assessing a printed product by point-wise comparison of the sample under assessment with an original, comprising: scanning said sample and said original to obtain reflectance values from each individual image point of the sample and the original; forming differential values between the reflectance values of corresponding image points of the sample and the original; adding, with the predetermined weighting, to the differential value of each image point the differential values of the image points adjacent to the respective image point to obtain added differential values for each image point; comparing said added differential values with a predetermined threshold; and, assessing the sample as faulty if the absolute amount of said added differential values exceeds said threshold at least in one image point.