Real-world video quality is tricky to measure: a bitrate that looks good for a crowd shot might be terrible for a close-up. Netflix, however, thinks it has the problem licked. It developed a tool that measures videos based on perceived quality, not just pure numbers. The technology works by gauging visual information fidelity (how much has changed?), detail loss and the effect of motion. The end result is a test that's much more reflective of real life, regardless of what you're watching; you know what should be appealing, whether it's a live-action drama or an animated kids' movie.