Background. In computer graphics, it can be a time-consuming process to render photorealistic images. This rendering process, called “physically based rendering” uses complex algorithms to calculate the behavior of light. Fortunately, most renderers offer the possibility to alter the render-settings, allowing for a decrease in render time, but this usually comes at the cost of a lower quality image.

Objectives. This study aims to identify what setting has the highest impact on the rendering process in the V-Ray renderer. It also examines if a perceived difference can be seen when reducing this setting.

Methods. To achieve this, an experiment was done where 22 participants would indicate their preference for rendered images. The images were rendered in V-Ray with different settings, which affected their respective render time differently. Additionally, an objective image metric was used to analyze the images and try to form a correlation with the subjective results.

Results. The results show that the anti-aliasing setting had the highest impact on render time as well as user preference. It was found that participants preferred images with at least 25% to 50% anti-aliasing depending on the scene. The objective results also coincided well enough with the subjective results that it could be used as a faster analytical tool to measure the quality of a computer-generated image. Prior knowledge of rendering was also taken into account but did not give conclusive results about user preferences.

Conclusions. From the results it can be concluded that anti-aliasing is the most important setting for achieving good subjective image quality in V-Ray. Additionally, the use of an objective image assessment tool can drastically speed up the process for targeting a specific visual quality goal.