Bragg peak position ( angle) as a function of the applied load on the composite film substrate. Red open symbols are the data before image processing by the `image cleaning' algorithm. Dark blue filled points are the data obtained after image processing. The solid blue line is the linear fit of this data as should be the case in the elastic linear regime. It is noteworthy that the high probability of having defective chips with XPAD3.1 is induced by the low energy used in experiment A. Uncertainties are estimated to be = ±0.005°.