In a method and apparatus for generating a phase-describing map in a firm that is usable to generate magnetic resonance (MR) image data, first and second sets of magnetic resonance echo raw data are acquired from a region of the examination subject, at two different echo times, said first and second sets of magnetic resonance echo raw data originating from two different chemical substance types. First and second image data sets of the defined region are reconstructed respectively from the first and second sets of magnetic resonance echo raw data. An energy function is determined that contains at least one term that places phase-describing values of map points of a phase-describing map in relation to each other dependent on a difference of the respective phase-describing values of the respective map points. The energy function is optimized to obtain an optimized phase-describing map.