A system and the like capable of stably displaying image information according to an object shot by infrared cameras by offsetting disadvantages of two-dimensional image processing and three-dimensional image processing. According to an image information processing system 100 of the present invention, a weighting factor calculation unit 140 calculates a first weighting factor C1 (0≦C1≦1) and a second weighting factor C2 (=1−C1), on the basis of a measured value of a variable according to a distance between infrared cameras 210 and an object. Moreover, a composite image recognition unit 150 recognizes a composite image area A composed of a first image area A1 recognized by a first image area recognition unit 110 through the infrared camera 210 by performing the two-dimensional image processing and the second image area A2 recognized by a second image area recognition unit 120 through the infrared cameras 210 by performing the three-dimensional image processing, with being weighted by the first weighting factor C1 and the second weighting factor C2, respectively. Then, the image information control unit 160 causes the HUD 110 to display a frame enclosing the composite image area A.