decorative banner

About motion blur


    When you view one frame of motion-picture film or video containing a moving object, the image is often blurred. This is because a frame represents a sample of time (in film, a sample is 1/24 of a second long). In that time, a moving object occupies more than one position as it travels across the frame, so it cannot be shown as a sharp, still object. The faster the object moves, the more it blurs. The camera shutter angle also affects the appearance of the blur.

    In contrast, in a single frame of a computer-generated animation, you may not be able to tell which objects are moving because all moving objects may appear as sharp and clear as nonmoving objects. Without motion blur, layer animation produces a strobe-like effect of distinct steps instead of an appearance of continuous change. Adding motion blur to layers you animate in After Effects makes layer motion appear smoother and more natural.

    You can use motion blur when you animate a layer--for example, moving a layer of text across the screen. You cannot add motion blur to motion that already exists within a layer, such as live-action video. If you want to smooth live-action video where you assigned a frame rate much lower or higher than the original, use frame blending. See Enhancing time-altered motion by blending frames and Using frame blending.

    Note: Previous versions of After Effects included an effect called Motion Blur. That effect is now named Directional Blur, to avoid confusion with motion blurring applied to layers.

Related Subtopics: