Evaluation of the impact of high frame rates on legibility in S3D film

There is growing interest in capturing and projecting movies at higher frame rates than the traditional 24 frames per second. Yet there has been little scientific assessment of the impact of higher frame rates (HFR) on the perceived quality of cinema content. Here we investigated the effect of frame rate, and associated variables (shutter angle and camera motion) on viewers' ability to discriminate letters in S3D movie clips captured by a professional film crew. The footage was filmed and projected at varying combinations of frame rate, camera speed and shutter angle. Our results showed that, overall, legibility improved with increased frame rate and reduced camera velocity. However, contrary to expectations, there was little effect of shutter angle on legibility. We also show that specific combinations of camera parameters can lead to dramatic reductions in legibility for localized regions in a scene.