title: A bound on null functions for digital imaging systems with positivity constraints.
abstract: There is an upper bound for the L(1) norm of the difference of two nonnegative object functions when they both produce the same data in a digital imaging system. This bound is achieved for a certain class of systems and an arbitrary nonnegative object. For the L(2) norm of the difference, with the same conditions on the object functions, there is no upper bound.
authors.forename: E
authors.initials: E
authors.lastname: Clarkson
authors.forename: H
authors.initials: H
authors.lastname: Barrett