5

To refine a key using Matte Tools
1 With the Keyer filter selected in the Layers list, set the View mode in the Filters Inspector
to Matte.
Matte mode lets you see how adjustments affect the transparency of the image. The
keyed image appears in grayscale: white areas represent solid pixels in the final matte;
black areas represent transparent pixels in the final matte; and varying levels of gray
represent translucent pixels in the final matte (darker gray is more transparent; lighter
gray is more opaque).
2 Click the disclosure triangle of the Matte Tools row of the Filters Inspector.
The row expands to reveal the Levels control, which adjusts the contrast of the matte.
Also revealed are the Shrink/Expand slider, the Soften slider, and the Erode slider.
3 Use the Levels control to modify transparency and contrast in the matte.
A general rule for using the Levels control is to drag the center Bias handle left to decrease
transparency in the matte or right to increase transparency in the matte. The Black slider
on the left and the White slider on the right modify contrast in the shadows and highlights
of the matte.
The effects of Levels adjustments are best seen when View is set to Matte. In this view,
the white area of the matte is the solid part, and the black area of the matte is the
transparent part. Gray is translucent, with lighter grays creating progressively more
transparency. With this in mind, here are some guidelines:
• Dragging the black bias handle right pushes gray areas to black, expanding areas of
transparency within the matte.
• Dragging the center bias handle left pushes the grays in the matte towards white,
widening solid areas of the key as semitransparent areas are made solid.
• Dragging the center bias handle right pushes the grays in the matte towards black,
widening transparent areas of the key as semitransparent areas are made transparent.
• Dragging the white bias handle left pushes the grays in the matte towards white,
expanding areas of solidity within the matte
4 Drag the Shrink/Expand slider left to shrink the matte inwards, widening holes in the
matte; drag the Shrink/Expand slider right to expand the matte outward, filling in holes
in the matte.
Original matte
Reducing Shrink/Expand Increasing Shrink/Expand
657Chapter 13 Keying