The trace correlation between an image region and its best-fitting plane-wave yields an easily interpreted seismic section. The resolution of the discontinuity map is about the size of the local patch that is used to estimate the best-fitting plane wave. The quality of the discontinuity map is comparable to similar to Amoco's original coherency attribute. In comparison to the correlation, alternative misfit measures of the locally best-fitting plane wave yielded inferior discontinuity maps.