Noise verification

Different from proof of ownership schemes the verification of watermark requires a key. Given an image JJ and a verification key KverifKverif​, we first try to recover a watermark W^W^ from JJ using a decoding function DD:

W^=D (J,Kverif)W^=D(J,Kverif​)

Next W^W^ is compared against WW, if the deviation is above some threshold TT:

∥W^−W∥≥T∥W^−W∥≥T

then JJ will be accepted otherwise rejected.