\section{Acknowledgments}%%%%I owe my familiarity with the asymptotic inversion theory to SergeyGoldin. A short discussion with Martin Tygel helped me betterunderstand the true-amplitude migration concept.I thank Jon Claerbout for helpful discussions and the sponsors of the StanfordExploration Project for the financial support of this work. Comments  from three anonymous reviewers helped to improve the paper.%%% Local Variables: %%% mode: latex%%% TeX-master: t%%% End: