1. A method of data processing in relation to a frustrated total internal reflection (FTIR)-based projection-type touch-sensing apparatus, wherein the touch-sensing apparatus is operable to generate projection signals representing radiation that has propagated on a plurality of propagation paths by total internal reflections inside a transmissive panel beneath a touch surface of the transmissive panel such that a touching object on the touch surface causes attenuation of at least one of the projection signals, said method comprising: generating by image reconstruction processing of the projection signals, a peak corresponding to a touching object on the touch surface; and generating, as a function of a time series of magnitude values, a time series of force values representing an application force of the touching object onto the touch surface, wherein a current force value in the time series of force values is generated as a function of a current magnitude value among the magnitude values and a current speed of the touching object.