Final Cut Motion Tracking Plugins
   

Pin Blur

 

Lyric's Pin Blur filter is an image manipulation filter that lets you track a feature moving within a clip and then apply a blur to a given elliptical area in the clip that follows the feature as it moves within the clip.

You can use Pin Blur to generate the classic "cop show" effect, obscuring a face or a feature in a clip by blurring just that part of the image as it moves around the frame. You can also achieve a localized "traveling" soft-focus effect by reducing the pinned blur radius and opacity.

It provides several features, including:

  • sub-pixel and center-of-weight motion tracking
  • feature selection on any clip frame
  • interactive, frame-by-frame tracking repair
  • track smoothing
  • pinned blur controls, including
    • offset from feature
    • height and width of blur area ellipse
    • rotation
    • edge-softening
    • opacity for traveling soft-focus effects

Pin Blur has a set of fixed steps you work through to get the final processed image. You select the step you wish to perform in the Step dropdown menu. The steps are:

  1. Select the feature to track and set the tracking options
  2. Start the motion track process
  3. When the tracking finishes, check it and optionally repair any tracking errors, including retracking portions of the clip
  4. Set the blur location and area, set blur parameters, and pin the blur area motion to the generated track

Doing things this way lets Pin Blur build a record of an entire motion track, so that it can support features like manual track correction, track smoothing and image preprocessing.

The first 3 steps are identical in all the Lyric Motion Tracking Plugins and are described in Tracking an Image Feature.

When you have created a satisfactory image motion track, select 4. Pin Blur in the Step dropdown menu to complete the pinning. Note that you can go back to the first 3 steps at any time to repair a track or track an alternative feature.

A circular area over the feature will blur and this blurred area should track the feature as you play or step through the clip. You can move the center of the blur area using the Blur Center point control, which will cause the blur to track the feature at that offset throughout the clip.

The blur area is an ellipse whose height, width and rotation can be set with the controls in the Pin Blur section. You can also soften the edge and adjust the amount of blur with the Edge Soften and Blur Radius controls.

The Blur Opacity can be used to achieve soft-focus effects. See the example below for suggested settings.

Smooth Track applies a smoothing filter to help reduce jerkiness in the track. You can see the smoothed version of the track with the Show Track option enabled.

The following example shows the right eye being tracked to pick up face movement and then an oval blur being pinned and offset to the center of the face. The final image shows the same blur adjusted and reduced in opacity to produce a soft-focus localized to the face that stays centered over the face as it moves.

Step 1, the Feature Center was placed over the eye and the Search Range increased to cover it and its frame-to-frame movement.
Step 2 generated the motion track.
Step 4 applied the blur, which was resized using blur Height & Width and centered over the face with the Blur Center point control.
The soft-focus effect was produced by reducing Blur Radius down to 10 or so pixels, and Blur Opacity down to about 50%. The blur area was also enlarged and the Edge Soften increased to cover the entire head.
 

You should render the composited clip while still working in the Filter tab to ensure that the recorded track is not lost. See the note here about when Final Cut will reset the track and how to protect your track and renderings.

Note also that final renderings in the Pin step will not contain any of the track displays that might be visible in the canvas.

 

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