1. An image processing device comprising: an image acquisition unit for acquiring a normal light observation image captured by an endoscope using white light as observation light and a special light observation image captured by the endoscope simultaneously with the normal light observation image using predetermined narrowband light as the observation light; and an image processing unit for subjecting the normal light observation image acquired by the image acquisition unit to predetermined processing to generate a processed normal light observation image and providing information of the processed normal light observation image to the special light observation image.