A program for causing a computer to execute a process for image processing, the process comprising: extracting a linear region from an image of an object captured by an imaging apparatus; determining a luminosity change in a direction traversing the linear region at each of a plurality of positions separate in a longitudinal direction of the linear region; and identifying a type of the linear region based on the luminosity changes at the plurality of positions; wherein the object is a concrete wall, and the types of the linear regions are a crack and a type other than the crack; the process is characterized in that: in the extracting, extracted is a linear region from each of a plurality of images captured while light of a plurality of colors being respectively radiated toward the object; in the determining of the luminosity change, determined is the luminosity change in a direction traversing each of the linear regions with respect to the linear regions of the plurality of images; and in the identifying, the type of the linear region is identified based on luminosity changes at a plurality of positions of the linear regions extracted from the plurality of images; the process further comprising: processing in which first statistics indicating luminosity changes at a plurality of positions of linear regions and registered being associated with a plurality of types are acquired, the acquired first statistics are compared with second statistics indicating luminosity changes at a plurality of positions of the linear regions extracted from the plurality of images, and the type of the linear region is determined based on a comparison result obtained by comparing the first statistics and the second statistics. extracting a linear region from an image of an object captured by an imaging apparatus; determining a luminosity change in a direction traversing the linear region at each of a plurality of positions separate in a longitudinal direction of the linear region; and identifying a type of the linear region based on the luminosity changes at the plurality of positions; wherein the object is a concrete wall, and the types of the linear regions are a crack and a type other than the crack; the process is characterized in that: in the extracting, extracted is a linear region from each of a plurality of images captured while light of a plurality of colors being respectively radiated toward the object; in the determining of the luminosity change, determined is the luminosity change in a direction traversing each of the linear regions with respect to the linear regions of the plurality of images; and in the identifying, the type of the linear region is identified based on luminosity changes at a plurality of positions of the linear regions extracted from the plurality of images; the process further comprising: processing in which first statistics indicating luminosity changes at a plurality of positions of linear regions and registered being associated with a plurality of types are acquired, the acquired first statistics are compared with second statistics indicating luminosity changes at a plurality of positions of the linear regions extracted from the plurality of images, and the type of the linear region is determined based on a comparison result obtained by comparing the first statistics and the second statistics. in the extracting, extracted is a linear region from each of a plurality of images captured while light of a plurality of colors being respectively radiated toward the object; in the determining of the luminosity change, determined is the luminosity change in a direction traversing each of the linear regions with respect to the linear regions of the plurality of images; and in the identifying, the type of the linear region is identified based on luminosity changes at a plurality of positions of the linear regions extracted from the plurality of images; the process further comprising: processing in which first statistics indicating luminosity changes at a plurality of positions of linear regions and registered being associated with a plurality of types are acquired, the acquired first statistics are compared with second statistics indicating luminosity changes at a plurality of positions of the linear regions extracted from the plurality of images, and the type of the linear region is determined based on a comparison result obtained by comparing the first statistics and the second statistics.