An image processing system (10,500) that executes at least one of a detection process of detecting a detection target which is damage in a structure and included in an image or a composition process of calculating a correspondence relationship between a plurality of images and compositing the plurality of images based on the correspondence relationship, the system comprising: an image acquisition unit that acquire one or a plurality of images obtained by capturing a subject; an image quality determination information acquisition unit that acquires at least two pieces of image quality determination information, each representing a determination result of an image quality in the images acquired using the image acquisition unit; an image processing target region decision unit that decides an image processing target region in the image or images acquired using the image acquisition unit, by using the image quality determination information acquired using the image quality determination information acquisition unit; and an image processing unit that executes at least one of the detection process or the composition process for the image processing target region decided using the image processing target region decision unit, wherein the image processing target region decision unit derives two or more temporary image processing target regions (240,240A) respectively corresponding to two or more pieces of the image quality determination information (32A,32B) and decides a region represented as a logical product of the two or more temporary image processing target regions as the image processing target region, wherein the image quality determination information acquisition unit includes an imaging condition acquisition unit that acquires an imaging condition in the capturing of the image, and the image processing target region decision unit decides at least one of the two or more temporary image processing target regions using at the imaging condition of the image, characterised in that the imaging condition acquisition unit acquires a type of lens and a focus position as the imaging condition, and based on the type of lens and the focus position, in a case where the focus position is in a center portion of an imaging range, the image processing target region decision unit decides a region that includes the center portion and is determined from characteristics of the lens as one of the two or more temporary image processing target regions (240,240A), and in a case where the focus position is in a peripheral portion of the imaging range, the image processing target region decision unit decides a region that includes the peripheral portion and is determined from the characteristics of the lens as one of the two or more temporary image processing target regions (240,240A). an image acquisition unit that acquire one or a plurality of images obtained by capturing a subject; an image quality determination information acquisition unit that acquires at least two pieces of image quality determination information, each representing a determination result of an image quality in the images acquired using the image acquisition unit; an image processing target region decision unit that decides an image processing target region in the image or images acquired using the image acquisition unit, by using the image quality determination information acquired using the image quality determination information acquisition unit; and an image processing unit that executes at least one of the detection process or the composition process for the image processing target region decided using the image processing target region decision unit, wherein the image processing target region decision unit derives two or more temporary image processing target regions (240,240A) respectively corresponding to two or more pieces of the image quality determination information (32A,32B) and decides a region represented as a logical product of the two or more temporary image processing target regions as the image processing target region, wherein the image quality determination information acquisition unit includes an imaging condition acquisition unit that acquires an imaging condition in the capturing of the image, and the image processing target region decision unit decides at least one of the two or more temporary image processing target regions using at the imaging condition of the image, characterised in that the imaging condition acquisition unit acquires a type of lens and a focus position as the imaging condition, and based on the type of lens and the focus position, in a case where the focus position is in a center portion of an imaging range, the image processing target region decision unit decides a region that includes the center portion and is determined from characteristics of the lens as one of the two or more temporary image processing target regions (240,240A), and in a case where the focus position is in a peripheral portion of the imaging range, the image processing target region decision unit decides a region that includes the peripheral portion and is determined from the characteristics of the lens as one of the two or more temporary image processing target regions (240,240A).