Image processing system, image processing method, and non-transitory storage medium

An image processing apparatus includes a first classification unit configured to classify each of a plurality of pixels included in a three-dimensional medical image using a first classifier for classifying each pixel into a plurality of classes including a class representing a first target region, a determination unit configured to determine an image region including the first target region and a second target region from the three-dimensional medical image based on a first classification result, a second classification unit configured to classify each of a plurality of pixels included in the determined image region using a second classifier for classifying each pixel into a plurality of classes including at least either one of a class representing the first target region and a class representing the second target region, and an integration unit configured to integrate the first and the second classification results to acquire a third classification result.