An image processing system (100, 500), comprising: an original image acquisition unit (101, 501) that acquires a first original image and a second original image; a luminance correction unit (104, 504) that acquires a luminance-corrected image by correcting a luminance value of the second original image such that a difference from a luminance value of the first original image decreases in accordance with an exposure condition related to each of the original images; and a background difference type object detection unit (105, 505) that detects an object by acquiring a background difference based on the luminance-corrected image, wherein the original image acquisition unit (101, 501) acquires the first original image and the second original image related to a plurality of different positions, each of the original images includes a stereo region and a monocular region, the stereo region is a region in which angles of view overlap between the original images related to the different positions, and the monocular region is a region in which the angles of view do not overlap between the original images related to the different positions, the image processing system (100, 500) includes an exposure condition adjustment unit (103, 503) that decides the exposure condition based on the stereo region of each of the original images, and the luminance correction unit (104, 504) acquires the luminance-corrected image related to one position by correcting the luminance value of the second original image related to said position such that a difference in the luminance value from the first original image related to said position in the monocular region related to said position decreases. an original image acquisition unit (101, 501) that acquires a first original image and a second original image; a luminance correction unit (104, 504) that acquires a luminance-corrected image by correcting a luminance value of the second original image such that a difference from a luminance value of the first original image decreases in accordance with an exposure condition related to each of the original images; and a background difference type object detection unit (105, 505) that detects an object by acquiring a background difference based on the luminance-corrected image, wherein the original image acquisition unit (101, 501) acquires the first original image and the second original image related to a plurality of different positions, each of the original images includes a stereo region and a monocular region, the stereo region is a region in which angles of view overlap between the original images related to the different positions, and the monocular region is a region in which the angles of view do not overlap between the original images related to the different positions, the image processing system (100, 500) includes an exposure condition adjustment unit (103, 503) that decides the exposure condition based on the stereo region of each of the original images, and the luminance correction unit (104, 504) acquires the luminance-corrected image related to one position by correcting the luminance value of the second original image related to said position such that a difference in the luminance value from the first original image related to said position in the monocular region related to said position decreases.