In film directing, a bias towards the representation of a particular gender can cause the audience to form a distorted stereotype of the gender role. The Bechdel test has been widely used to objectively judge the existence of such bias in films. However, because its analysis is based solely on the script of a film, the Bechdel test is incapable of considering the broad spectrum of bias that films can have as a visual medium. This study proposes a more comprehensive analysis system that quantifies the degree of bias in the visual representations of female and male characters in commercial films. By analyzing the image frames of a movie using the latest image analysis techniques, a total of 40 films were analyzed based on 8 quantitative indices. The result demonstrates that there exists a statistically significant difference in the visual representation of female and male characters. Specifically, female characters showed lower values in emotional diversity, spatial occupancy, and temporal occupancy compared to male characters in commercial films. Further, female characters were less likely to wear eyeglasses and also appeared more in static scenes, such as indoors.