1. A non-transitory computer-readable recording medium that stores therein a computer program for generating a vehicle image for identifying a vehicle from an original image, the computer program causing a computer to execute: cutting a vehicle-body area out of the original image; checking whether it is possible to recognize all numbers and letters on a license plate extracted from the vehicle-body area or not; setting a data reduction level for limiting or prohibiting data reduction of the original image in a multi-level based on a result of the checking; identifying a component of the vehicle in the vehicle-body area; defining an identification region including an identification component for identifying the vehicle based on the component and the data reduction level; extracting the identification region from the original image; and generating the vehicle image based on extracted identification region.