In complex geologic environments, imaging of seismic reflection data requires model-driven depth migration. It is well known that such migration is sensitive to velocity errors. If the velocity model used in migration does not correctly model the travel-times of reflection events, the images of reflectors on migrated shot profiles will be distorted from the true images of the earth. By solving the Eiconal equation, I find a residual-moveout equation that can be used in estimating residual velocities, and a residual-migration operator that can revise the distortion of the images on migrated shot profiles. For a constant-velocity medium, these results are precise in the kinematic sense.