A method is disclosed for creating and outputting a masked parameter map (eg, hemoglobin oxygenation) that reflects parameters in a first parameter map (eg, relative oxygenation) and a second parameter map (eg, relative hemoglobin). In an exemplary embodiment, the method includes generating a first parameter map, generating a second parameter map, and then masked to reflect parameters in the first parameter map and the second parameter map. Generating a parameter map. The masked map presents information that is not readily apparent from the first parameter map and the second parameter map and that cannot be obtained independently from the first parameter map and the second parameter map. Can do. The first parameter map may be based in part on two photoacoustic images created using different wavelengths of light. The first parameter map reflects a region within the tissue volume that has a different response to longer wavelength light events as compared to shorter wavelength light events. The second parameter map reflects regions within the tissue volume that have a stronger response to longer wavelength light events and shorter wavelength light events than the surrounding regions. A masked parameter map is output that reflects a combination of information in the first parameter map and information in the second parameter map. In one embodiment, the masked parameter map generates a mask that reflects a combination of information in the first parameter map and information in the second parameter map, with respect to one of the first parameter map and the second parameter map. It is generated by applying the mask and thereby forming a masked parameter map. In one embodiment, one or more of the parameter maps are registered and superimposed on an ultrasound image of the same tissue volume before being output. [Selection] Figure 32第１パラメータマップ（例えば相対酸素化）および第２パラメータマップ（例えば相対ヘモグロビン）におけるパラメータを反映するマスクされたパラメータマップ（例えばヘモグロビン酸素化など）を作成および出力するための方法が開示される。例示的実施形態では、この方法は、第１パラメータマップを生成す
