Though the continuous wave equation defines a unitary operator, many operators based on it are not unitary because many approximations are made to be implemented numerically in finite and discrete space. The nonunitary property of the operators produces many artifacts in the solution space when is applied to data that was generated by a continuous unitary operator, such as real seismic data. This paper presents a method of reducing these kinds of artifacts in migration, datuming, and interpolation by using the technique of a least-squares optimization.