<table border="0" cellpadding="20px" cellspacing="0" width="100%"><tr><td><div class="breadcrumbs"><a href="1_7_18_5.html" title="Using the Track Matte Key effect">Previous</a> | <a href="1_7_18_7.html" title="Inverting or hiding alpha channels">Next</a> | <a href="1_7_0_0.html">Applying Effects and Transitions</a> > <a href="1_7_18_0.html">About keying effects</a></div><h4 class="head2">Hiding unwanted objects with Garbage Matte keying effects</h4><hr /><ol><p class="paragraph">Sometimes a color-based keying effect properly removes a background, but undesired objects still appear, such as a microphone or cable. Use a <span class="Emphasis">garbage matte</span> keying effect to mask out those objects. </p><p class="paragraph">The Effect Controls window provides options for shaping garbage mattes. Each option represents the position of an individual point on the edge of the garbage matte, measured in <span class="Emphasis">x</span> and <span class="Emphasis">y</span> pixel coordinates from the top left corner of the frame. You can reshape the matte by changing the numeric values in the Effect Controls window or by dragging the point handles in the Monitor window. The name of each garbage matte effect reflects the number of handles it provides: Four-Point Garbage Matte, Eight-Point Garbage Matte, and Sixteen-Point Garbage Matte.</p><div class="anchorc"><img src="images/ae_31.gif" alt="The unwanted background (left) is masked out by reshaping the Four-Point Garbage Matte in the Monitor window (center); then the Green Screen Key effect is applied (right) to superimpose the boy over the underlying track." height="126" width="470" /></div><div class="caption">The unwanted background (left) is masked out by reshaping the Four-Point Garbage Matte in the Monitor window (center); then the Green Screen Key effect is applied (right) to superimpose the boy over the underlying track.</div></ol><p class="headstep">To create a garbage matte:</p><ol><li class="numberstep" type="1" value="1">Place a clip in a track.</li><li class="numberstep" type="1" value="2">In the Effects window, expand the Keying folder, and drag a garbage matte effect to the clip.</li><li class="numberstep" type="1" value="3">In the Effect Controls window, click the triangle next to the effect's name to expand it.</li><li class="numberstep" type="1" value="4">Do one of the following to reshape the matte:</li><ul><li class="bullet" type="disc">Click the effect name to display the garbage matte effect's point handles in the Monitor view, and drag the handles.</li><li class="bullet" type="disc">Change the garbage matte effect's values in the Effect Controls window.</li></ul></ol><hr /><div class="breadcrumbs"><a href="1_7_18_5.html" title="Using the Track Matte Key effect">Previous</a> | <a href="1_7_18_7.html" title="Inverting or hiding alpha channels">Next</a> | <a href="#top">Top</a> | <a href="1_7_0_0.html">Applying Effects and Transitions</a> > <a href="1_7_18_0.html">About keying effects</a></div></td></tr></table>
