1. An image generation apparatus comprising: a processor which is operable to: extract characteristic information of a hair-tip region in a face image and characteristic information of an entire hair region in the face image; specify a predetermined number of candidate hairstyle images from among a plurality of predetermined hairstyle images, based on the extracted characteristic information of the hair-tip region; select a final hairstyle image from among the specified candidate hairstyle images, based on the extracted characteristic information of the entire hair region; and generate a portrait image of a face in the face image using the selected final hairstyle image.