An image processing system and the like capable of recognizing a lane mark in a road image with high accuracy are provided even if a light illumination state on a road surface is partially different. According to the image processing system (100) mounted on a vehicle (10), a color component (Rij, Gij, Bij) of the first pixel (Pij) included in an area (Aij) set in the road image is corrected with reference to a color component (Rik, Gik, Bik) of a second pixel (Pik) in view of a fact that it is highly probable that the color component of the second pixel included in the area along with the first pixel is affected by a shadow or light on the road surface. This reduces the effect of the shadow or light on the road surface and the actual color of a road surface portion corresponding to the first pixel can be sufficiently reflected in the color components (Rij, Gij, Bij) of the first pixel (Pij) and consequently in a feature value (Qij). Therefore, a lane mark (M) and its edge (E) are recognized in the road image on the basis of the feature value (Qij) of each pixel (Pij) in the road image.