A nonexpansive monotonicity constraint operator for use in constrained iterative deconvolution

This letter describes a nonexpansive monotonicity constraint operator. It can be used in constrained iterative deconvolution in order to compute impulse response functions which are known to be piecewise monotonous or piecewise constant. The operator may also be combined with, for instance, positivity and finite support constraint operators to put further constraints upon the impulse response function. Constrained deconvolutions are generally less noise-sensitive than nonconstrained deconvolutions.