Have you ever needed to blur out a logo or someone's face or even a license plate? This method also works if you would rather create a mosaic effect to disguise something. This is a general guide on how to create this effect, not a deep tutorial on motion tracking.

You will need:

• AE 7 Pro to open the project files, however, this can be done with older versions of After Effects.

Instructions

1. Open your footage in After Effects.
2. Create a new comp and drag the footage that you would like to track into it.
3. Set your workspace to Motion Track in the upper right corner of After Effects. This will bring up the Tracker Controls and hide a lot of the palettes that you do not need to see.
   
   
   
4. In the Tracker Control Palette, choose the layer/footage that you would like to track. Your footage will open it the Layer Window.
   
   
   
5. Click the Track motion button.
   
   
   
6. Set a work area in the timeline, so only the area that you would like to be tracked is included.
7. Set up your Tracking Region. The crosshair in the middle should be put at the point you would like to track. It is easier to track something that has an area of high contrast (like the center of this BMW logo) or a large difference in hue.
   
   
   
   Your Feature region should encompass the feature that you would like to track, in this case, the BMW embroidery.
   
   The Search Region is the area that the logo moves through. The lovely lady in the video is moving quite a bit, so the area is fairly large. Move throughout your timeline to check to see if your object is in your Search Region at all times. Scale the Search Region as needed. Don't make it too large though, because it will increase tracking time, or create unpredictable results.
8. Click the Options button in the Motion Tracker palette. A popup window appears.
   The default channel is Luminance. You'll have to look at your footage to determine what is the best channel to track. My footage has fields, so I choose Track Fields. I also chose to use the Adapt Feature because the model in my video turns to hide the logo at one point (not shown in clip). This will make the tracker guess where the track should be placed.
   
9. Click the Analyze forward button. These are VCR like buttons that should be pretty familiar to you.
   
   Once clicked, it will go through your footage. It will take some time. Keep an eye on it. If your track suddenly goes off track, click the stop button in the Analyze area to stop the track.
   
   Keyframes have been added in your timeline for the Feature Center, Confidence and Attach Point. Find the point where things went wrong, delete those keyframes and go to the last good frame. It's easiest to use the comp window as a reference. You may need to make some adjustments in your Options or in your Tracking Regions. You also may want to re-adjust your work area to start at the end of the region that you have already done. This last step is not especially necessary, but it always helps me know where the correct area is if I need to redo it again. It just makes re-tracking easier.
   
   
10. Add an Adjustment Layer (Layer > New > Adjustment Layer).
11. Select the Adjustment Layer. Tap the P key to bring up Position. We're going to set an Expression on Position in the Adjustment Layer to link it to either the Attach Point or Feature Center of the Motion Tracker.
    
    Option+click the stopwatch for Position. An expression is now added. You don't need to type or do any programming here. All you need to do is click and drag the pickwhip to the Feature Center or the attach point. My values for both are exactly the same, but your values may be completely different. Use whichever works best for you. You may need to go back and switch. If so, delete the expression in the timeline and click and drag to the other Track Point item. You can do this at any time.
    
    
12. Select your Adjustment Layer. Use the Rectangular Mask too to draw a square around your logo or item that you would like to obscure. Alternately, you can use the Circle Tool or use the pen tool and draw a polygon. If you draw your own, make sure that you close your mask.
13. Apply a Blur or Mosaic to your Adjustment Layer. Adjust as needed. Below are my settings.
    
    
14. If you're seeing hard edges, feather your mask. Tap the F key to bring up your Mask Feather options. See image above for my settings.
15. If your blur or mosaic is not covering the right area, move the position of your mask by changing the Anchor Point (A) values for your Adjustment Layer. Alternately, move your mask. You will not be able to move the position because of the expression tied to it.