Adaptive image processing device performs image processing with a simple configuration on a composite image including areas having different characteristics by changing a process depending on the number of combined images in each area of the composite image configured by combining a plurality of images. The image processing device acquires a plurality of images and generates a composite image. When the composite image is generated, the image processing device realizes a process of determining the number of combined images for detecting the number of images to be combined for each area of the composite image and holding the number as information about the number of combined images, and an image processing parameter switching process for switching a parameter of image processing to be performed on each area of the composite image according to the information about the number of combined images.