Join Todd Kopriva for an in-depth discussion in this video The Rolling Shutter Repair feature, part of After Effects CS6 New Features Overview.
After Effects CS6 includes a new effect called the Rolling Shutter Repair effect. As the name indicates, this effect is intended to repair a certain kind of distortion that's caused by Rolling Shutter. Rolling Shutter refers to the fact that the image is not captured all at once in each frame. Rather, the Shutter rolls down the image. The top of the image is captured first then the next scan line, all the way down until the bottom is reached, and then scanning begins at the top. This means that the top of the image is capture before the bottom of the image.
Since the top and the bottom of the image are not captured at the same time, if there's motion in the image, like there is in this one here, there will be a skew in vertical lines. As in this whiteboard, which should have a straight up and down vertical edge. I'll click Run Preview to play this movie. And this is just a mobile phone camera being moved back and forth in front of a white board that has straight edges. It should be pointing straight up and down.
But you can see that there's considerable distortion. So, let's try the Rolling Shutter Repair effect. In the Effects and Presets panel, I'll type Rolling and drag it onto the layer in the Composition panel. And immediately, just with the default settings, things seem quite a bit better. I'm going to turn the effect off by clicking the Effects switch and back on again. The first Rolling Shutter rate is a fraction. It's the time it takes for a frame to be captured divided by the time between frames.
For a DSLR camera, this is often between 50 and 70%. The default here is 50%, so that will often match a DSLR camera. But for mobile phone cameras, it tends to be closer towards 100%. You don't really need to remember that detail. Rather, you need to think in terms of adjusting this value until the things that should be vertical lines, show up as vertical. Let's drag this a little bit to increase the number. And notice how the image is skewed a little bit more one way or the other.
I think that's actually a bit better for this frame. Let's play through the movie with these settings. There still seems to be a little bit of distortion there. Let's stop on another frame. Let's drag forward, here. Or we can see if we can line up this door edge a little better.
And I'll go ahead a few more frames to look at another part of the movie. So, I'm just going through a few parts to see which are the worst and seeing if I can correct the Rolling Shutter artifacts there. So, in order to correct the artifacts here, I had to go to 100%, maybe just a little bit less. That seems to be about as well as we can do here, so I'll hit Play again, click the Ran Preview button.
Nope. There's still a little wobble, but it's still a lot better than it was. Let's turn the effect off again and then back on so we can see the difference. The next property is Scan Direction. Top to bottom, bottom to top, left to right, or right to left. Most cameras scan from top to bottom, but considering the fact that you can rotate a camera, if you were to turn it upside down, then the scan direction would essentially be bottom to top. So, just keep in mind that you may have to change this if the camera was rotated. You'll normally be able to tell just by looking at the image. In the Advanced section, the method can either be Warp or Pixel Motion. In both cases, a number of points are tracked in the image. But in the case of Warp, only a sparse set of points are tracked. In the case of Pixel Motion, every pixel in the image is tracked. This takes much more processing power, but sometimes going to get better results. If Warp is selected, you can choose to do Detailed Analysis to use more tracking points.
And if Pixel Motion is selected, you can choose to increase the amount of Pixel Motion detail. For all of these, you may simply want to experiment, and see which settings give you the best results. I find that Warp very often does a good job, and I don't usually need to use Detailed Analysis, which if I do use it, increases the processing time. So, give it a try. If you find that your movies have Rolling Shutter ripple, or jello cam, then apply the Rolling Shutter Repair effect.
You may very often find that simply applying the effect and leaving it at the default settings can remove much of the distortion.
- 3D animation
- User interface changes and removed features