1. An image processing system comprising: a first data input unit to which a captured image, which is obtained by capturing an image of a scene viewed from a vehicle, is input; a first feature point extraction unit that extracts image feature points from the captured image input to the first data input unit; an image-capturing situation information obtaining unit that obtains image-capturing situation information indicating a possibility that a specific subject is included in the captured image input to the first data input unit; a feature point importance degree determination unit that determines importance degrees of the image feature points extracted by the first feature point extraction unit, based on the image-capturing situation information; an image feature point data generation unit that generates image feature point data for each captured image using the image feature points extracted by the first feature point extraction unit, based on the importance degrees; and a reference data database creation unit that generates reference data used when scenic image recognition is performed, by associating the image feature point data with image-capturing attribute information, and creates a reference data database that is a database of the reference data, wherein the image-capturing attribute information includes an image-capturing position at which the image is captured to obtain the captured image corresponding to the image feature point data.