After a plurality of differently exposed images are obtained, and tone levels of the plurality of images are adjusted, image elements corresponding to changes of objects are detected based on pixel value differences between the plurality of images. Then, the numbers of blown-out highlight and shadow-detail loss image elements in the image elements corresponding to the changes of the objects are counted for the plurality of images. Then, an image in which the total of the numbers of image elements is smallest is selected. Furthermore, image elements corresponding to the changes of the objects in the selected image are used as those corresponding to image elements corresponding to the changes of the objects in an HDR image to be generated.