[Aim] To appropriately determine a part to be excised, considering a function level of a liver[Solution Means] A morphology image representing the morphology of a liver including a blood vessel in the inside thereof and a function image representing a function level at each position of the liver are obtained. A blood vessel region representing a blood vessel dominating the liver is extracted from the morphology image. A specific partial region in the extracted blood vessel region and a dominated region in the liver are determined, and the dominated region being dominated by a blood vessel in the partial region. In that case, at least one of the partial region determination step and the dominated region determination step is performed by using the function image.
