An image processing system or the like capable of with high precision recognizing a lane mark in a road image even if light irradiation conditions onto a road surface are partially different. According to an image processing system (100) mounted on a vehicle (10), in view of a high probability with which the color components of a second pixel included in an area along with a first pixel are receiving effects of shadows or lights on a road surface portion, the color components Rij, Gij, Bij of the first pixel Pij included in an area Aij set in a road surface image are corrected based on the color components Rik, Gik, Bik of the second pixel Pik. Accordingly, the effects of shadows or lights on a road surface can be reduced, and the actual color of a road surface portion equivalent to the first pixel can be satisfactorily reflected in the color components Rij, Gij, Bij of the first pixel Pij and accordingly in a feature quantity Qij. Therefore, a lane mark M and its edge E can be recognized in a road surface image based on the feature quantity Qij of each pixel Pij of a road surface image.