1. An image region extracting apparatus that extracts, from an image photographed by a camera, a target region based on a designation region, the apparatus comprising: a control circuit configured to acquire a pixel value change pattern and a distance change pattern of each part of the image, the pixel value change pattern being a spatial change characteristic of a pixel value component, and the distance change pattern being a spatial change characteristic of a distance component indicating a distance from a view point of the camera to a subject; and the control circuit being further configured to extract the target region based on similarities of the pixel value change pattern and the distance change pattern between the designation region and each part of the image.