Measuring the perceived visual realism of images

• Authors: Pablo Mauricio Rademacher;Gary Bishop
• Venue: Measuring the perceived visual realism of images
• Year: 2003

One of the main goals of computer graphics research is to develop techniques for creating images that look real—i.e., indistinguishable from photographs. Most existing work on this problem has focused on image synthesis methods, such as the simulation of the physics of light transport and the reprojection of photographic samples. However, the existing research has been conducted without a clear understanding of how it is that people determine whether an image looks real or not real. There has never been an objectively tested, operational definition of realism for images, in terms of the visual factors that comprise them. If the perceptual cues behind the assessment of realism were understood, then rendering algorithms could be developed to directly target these cues. This work introduces an experimental method for measuring the perceived visual realism of images, and presents the results of a series of controlled human participant experiments. These experiments investigate the following visual factors: shadow softness, surface smoothness, number of objects, mix of object shapes, and number of light sources. The experiments yield qualitative and quantitative results, confirm some common assertions about realism, and contradict others. They demonstrate that participants untrained in computer graphics converge upon a common interpretation of the term real, with regard to images. The experimental method can be performed using either photographs or computer-generated images, which enables the future investigation of a wide range of visual factors.