Autodesk 62205-051408-9001 User Guide - Page 640

23 Keying Note: Adjusting these values increases the contrast and may harden the edges of the matte. Using Shrink, Blur, and Erode to Refine the Edges of the Key In many cases, adjusting softness and tolerance is not enough to remove all the color spill from the edge of the front subject. Talent composited on a white Color spill around a strand background of hair One way to change the color of the pixels around the edge is using color correction. For more information, see Removing Background Spill and Color Correcting Clips. Another way to remove the unwanted color from the edge of the key is to make those pixels more transparent. To do this, use the Shrink, Erode, and Blur tools to modify the edge of the matte. Use Shrink, Blur, and Erode to soften the matte and eliminate the noise that may appear in the edges when you play the keyed clip. Since the Keyer has sub-pixel matte controls, a small amount of blur and erode can produce very good results. Note: The Shrink, Erode, and Blur tools are based on the filter type specified in the Setup controls. By default, a proportional Gaussian filter is used. See Setup Controls. To access the Shrink, Blur, and Erode tools: Click the Matte button under the Key button in the Keyer Controls panel. Note: You can access these same tools in the independent Matte Controls operator. To add this operator, choose Operators | Keying | Matte Controls. Shrink This tool removes pixels from the edge of the matte. To shrink the edge of the matte: Enable Shrink and set the shrink width. A negative value expands the matte. Pixels are removed from the edge of the matte. This has the effect of cutting away at the color spill around the edge of the subject. Notice how you lose some edge detail if the shrink value is too high (in this case 1.8). Erode This tool blends the light and dark edges of the matte. This is like feathering the contour of the matte. Like the Shrink tool, Erode can remove fine detail from the edge. 624