For the purpose of identifying the phases of water and fat in a complex image captured using magnetic resonance, a complex image G1 is divided into a multiplicity of sections; if the phases of water and fat can be identified from a phase histogram of one section Sc, the phases of water and fat are obtained from a phase histogram of the section; if the phases cannot be identified, phase histograms of proximate sections in a predefined range C1 are added; if the phases of water and fat can be identified from the additive phase histogram, the phases of water and fat are obtained from the additive phase histogram; and if the phases cannot be identified, the same processing is repeated with stepwise enlargement of the predefined range. |