Anti-Judder and Motion Smoothing Technology Analyzed

Notice a new television that looks ultra smooth? Motion so smooth that you almost can't believe what you are seeing? Does it look unbelievably clear to your eyes? Does it look incredibly fake? Well, if you have noticed this, you are more than likely noticing motion smoothing technologies at work. There is plenty of debate surrounding this technology, and there are some that think that it is actually bad for the movie industry. So let's dive in and explore the issues.

Translating Film to Video

This is all a big issue for one reason and one reason only: film is shot at 24 frames per second while most electronic equipment is optimized to display content at 60 frames per second. This is the core issue at hand. This is why I'm writing this article.

Film is shot at 24 frames per second for two reasons: (1) it creates a more cinema-quality effect and (2) it is currently what cinemas are prepared to display. It creates a more cinema-quality experience because the motion is a bit slower and more "film-like" than if you take a camcorder and go shoot a homemade video. And 24 frames per second is what cinemas have the equipment to display — upgrading all of the movie theaters throughout the country at this point in time in order to upgrade a frame rate doesn't make much financial sense to a lot of people in the industry.

But the frame rate isn't necessarily the problem. It's the way our electronic devices handle it that is. The display you are looking at right now is probably refreshing at 60Hz (or 60 frames per second) or 120Hz (120 frames per second). So if I a movie is shot at 30 or 60 frames per second, making the transition to a computer display isn't that difficult, as you can divide 30 into 60 twice or 60 into 60 once. It's simple math.

However, if you want to transform 24 frames per second into 60Hz (or 60 frames per second), that becomes a bit of a problem. This is where 3:2 pulldown comes into play. It is a technique that renders some frames more than once in order to compensate for the fact that the film is adapting to 60Hz. The math, unfortunately, doesn't add up. And this results in artifacts, motion blur, and other issues that I will discuss below.

But new televisions have come out that feature 120Hz refresh rates. If you do the math, 120 divided by 24 equals 5, which is a nice round number. This means that there will be a much better display for content that is shot at 24 and 60 frames per second. So everything is good, right?

Well, not really.

The problem is that with a 120Hz television and 24 frames per second content is that you have 5 refreshes for every single frame of a piece of content. That means four of those refreshes are essentially wasted. This isn't necessarily the end of the world — the film is rendered as it was intended to be by the director, giving you that cinema-quality effect. But it means there that there is room for experimentation, which is exactly what the display industry is doing.

This is where motion smoothing (also referred to as anti-judder) technologies come into play.

Anti-Judder Technology

This technology simply takes those leftover refreshes and uses that as an opportunity to simulate extra frames of motion that make the whole picture appear smoother. It does this by analyzing the difference between one frame and the next, and then interpolating the frames in between those two actual frames, which works remarkably well. It's almost like magic, but even better.

This results in much more smoother motion on screen, especially with scenes with a lot of action and high-paced movement. Some people really enjoy this increase in motion and clarity, and it is particularly good when it comes to sports. But this, too, relies on the viewer's preferences, because some people don't appreciate this effect at all.

Others believe this effect to result in fake looking motion that is captured from a home video camera. In other words, it takes away from the cinema feel that a movie provides. This is something I have noticed personally when viewing movies with a television that has anti-judder technology enabled.

See where this could be a problem?

Most televisions these days have a way to disable the anti-judder technology that smooths out the motion between frames, and while most people won't even bother to change it, people should be aware of its existence, especially if the motion appears fake or unreal.

So, like most things in life, it is a compromise between smoothness in motion or authenticity of a motion picture-like experience. I fall in the latter group, but everyone has their own preference.