What is motion blur in video editing? Why should you use it


We’ve all seen those transitional animations or video montages where something just doesn’t look quite right; movement does not appear natural or reading will be jerky. Usually this is because it was edited without using any motion blur effect.

We’re going to discuss what motion blur is, why you should use it, and give some examples so you can see for yourself that we’re not lying; video edits without motion blur just look lousy. If you are a video editor, we highly recommend that you stick with this one.

What is motion blur in video editing?

Video editor working in the office

Motion blur is a common term in photography and videography. And while the end result of this recording feature is quite similar to what we’re discussing here, it’s not quite the same.

We are talking about the motion blur effect in video editing. The examples we are going to give here all happen after the fact; no one is using a camera or recording anything. These are editors whose clips are imported and ready to edit with motion, looking for a way to make their edits natural and easy for viewers to digest.

The motion blur effect (or just … motion blur) has been designed to make it easier for us to observe movement in videos, making it a pleasant experience. An overly simplistic way to describe motion blur: it adds blur to video footage. But there is so much more to this; stay in the corner and you’ll see.


Why you should use motion blur in your edits

Motion blur people walking

Remember, video editing is digital, so the way a program or computer processes things is a far cry from what our organic minds do. This includes sensory processing such as sight. Natural-looking movement will always involve a degree of blurring, at least for the human eye – cats can apparently observe motion without blurring at up to 100 frames per second!

When we observe motion without blurring, like that produced by a computer, we can instantly tell that it is unnatural and will feel mechanical to us. This happens when you don’t add motion blur to clips that have been edited with motion; PowerPoint presentation vibes, yuck.

Besides not looking natural, video clips without motion blur can also appear choppy; that’s a big no-no for video editors, we want our work to be up to par. Whether the footage was shot with camera settings that did not involve motion blur, or if the quality of video clips is simply poor for some reason, a motion blur effect can mitigate this stuttering.

Work with motion blur in video editing

Most video editing programs offer motion blur, whether it’s desktop software or mobile editing apps, at least the more comprehensive ones. The motion blur effect can usually be found among all of the other effects, or it will be listed separately as a tool, depending on what you are editing. Either way, it’s the same.

Below is the location of the Motion Blur tool in After Effects. A motion blur effect icon will usually have some sort of repeated shape or animation, like these little circles.

After Effects motion blur tool

Sometimes motion blur will have a different name or different applications. For example, in the Video Star mobile editing app, motion blur is called “tracking blur”. While the Motion Blur effect in the app acts more like an optical flow, which is used for slow motion editing. More on that later.

Related: How To Get The Twixtor Slow Motion Effect On An iPhone

Editing with movement

Motion blur should be applied to all video clips being edited with motion; we can also refer to this as animation or motion editing in this case. He understands:

  • Zoom in or out.

  • Turning point.

  • Pan in any direction, or simply by changing the position of the frame.

  • Text in motion.

  • Moving 2D and 3D objects.

Keep in mind that when we talk about videos with motion, this is not referring to video footage that already features movement, such as people walking around. Motion blur will have no effect on this.

Motion blur will only work with video clips being edited with motion techniques in the editing program. For example, if you perform a zoom transition effect from one clip to another and the screen begins to zoom in on the image, that zoom effect is what the motion blur effect will attach to. .

How does motion blur work?

What does motion blur look like? Wouldn’t that blur the whole frame when applied? No, editing programs are smarter than that.

When motion blur is applied to a clip that has been edited with motion (motion effect), it’s an automated process from there, and some programs allow you to change the settings as well.

Motion blur will automatically detect motion, which means it detects the editing techniques you’ve used to make things move on the screen. When motion blur is on and it detects these movements, the effect shifts into high gear.

The intensity of the motion blur and the appearance of the clip will depend on how you edited it, and much of it depends on the keyframe interpolation; support with us …

Related: What Are Keyframes in Video Editing?

When the editing technique has linear interpolation, it means that the motion effect will move at the same speed until it stops. For example, if you add a zoom effect to a clip with linear interpolation, it will zoom in or out at a steady rate. In this case, the motion blur will be the same throughout the zooming time.

But if the editing technique uses Bézier interpolation, the speed of the motion effect will change throughout. For example, a Bezier interpolated zoom effect might start to zoom in or out slowly and become exponentially faster when it reaches the end. In this case, the motion blur effect will also increase.

Basically, the faster and more hardcore the editing technique (motion effect), the more blur you will get with the motion blur, and vice versa.

Let’s show what it looks like. We edited a clip with a zoom motion effect and bezier tween, and below is a comparison of the clip with and without motion blur.

With motion blur:

After Effects Zoom effect Bézier interpolation Motion blur

Without motion blur:

After Effects Zoom effect Bezier interpolation No motion blur

Do you see what we mean? The blur only kicks in when the zoom effect really starts to activate, which is close to the end of the clip thanks to Bézier interpolation. And a clip without any motion blur will be sharp and not blurry throughout playback, resulting in that mechanical-looking movement.

Is motion blur the same as optical flow?

It depends on who you ask. Optical Flow is a feature specially designed to combat jerking in videos that have been edited in slow motion.

When the footage is slowed down it will “stretch” its frames, and when the fps is not very high there will not be enough frames to create smooth playback, it will essentially “jump” from frame to frame. the next one.

The optical flow will guess what the missing frames in between would have looked like and generate new ones to fill in the gaps, and during playback it will be smooth navigation.

So where does the motion blur come from? Sometimes the optical flow will be labeled as motion blur, such as with the Video Star mobile editing app pictured below. And sometimes the motion blur itself can also help solve this dilemma of “stretched images” in slow-motion editing, depending on how the program designed its motion blur to work.

Video Star Motion Blur (Optical flow)

Don’t worry when you see the terms “optical flow” and “motion blur” used interchangeably, as it will depend on the program and how the developers design its effects.

Related: How to Record and Edit Slo-Mo Videos on Your iPhone

Create natural-looking movement with motion blur

It seems like there are a million things to follow when editing videos, but this is one thing you’ll want to remember. Motion blur is essential for producing edits with natural movement. Remember to activate this effect the next time you perform movement effects, the program will take care of the rest for you.

Person using video editing software

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