Photorealism has been one of essential goals for virtual reality. The state-of-the-art techniques employ various rendering algorithms to simulate physically accurate light transport for generating the photorealistic appearance of scene. However, they still require a labor-intensive tone mapping and color tunes by an experienced artist. In this paper, we propose an automatic photorealism enhancement algorithm by manipulating the color distribution of graphics to match with that of real photographs. Based on the hypothesis that photorealism is highly correlated with the frequency of color characteristics appearing in real photographs, we find principal color components. Then, we transfer the statistical characteristics of photographs onto graphics so to enhance their photorealism. Experiments and a user study have confirmed the effectiveness of proposed method.