Abstract: A method of measuring the thickness profile of a film produced in a blow film line having a rotatable pull-off rig in which a flattened film tube is scanned by performing individual measurements at measurement positions distributed over the width over the film tube and, in each individual measurement, the total thickness of two segments of the film tube is measured that are superposed at the measurement position, the thickness profile is calculated from the measured values obtained for a number individual measurements that is larger than the number of measurement positions, the improvement including the steps of training a neural network with measured values for the total thicknesses, which measured values have been obtained in simulated or real measurement processes with known thickness profiles and supplying the measured results obtained by scanning the film tube to the neural network for calculating the thickness profile.