PROBLEM TO BE SOLVED: To accurately extract a lesion having faint opacity.SOLUTION: An image processing apparatus for extracting a lesion having a ground glass opacity from an image includes a changing section for changing a pixel value corresponding to a candidate area of the ground glass opacity to a range of a predetermined pixel value, a first feature quantity extraction section for acquiring a first feature quantity from the image whose pixel value is changed, and an extraction section for extracting the lesion from the image on the basis of the first feature quantity.SELECTED DRAWING: Figure 3
