Apple Motion 5.1.1 - Manual (Page 490)

Chapter 13 Keying 490
Note: To remove a Sample Color selection box or Edges control, select the box or control, then
press Delete. Alternatively, Option-click inside the selection box or control line.
Additional key controls
•
Strength: Use this slider to adjust the tolerance (core transparency) of the Keyer filter’s
automatic sampling. The default value is 100%. Reducing this value narrows the range of color
sampled, resulting in less transparency in the keyed image. Increasing the Strength value
expands the range of color sampled, resulting in more transparency in the keyed image. The
Strength parameter is useful to retrieve areas of semitransparent detail such as hair, smoke, or
reflections.
Important: Setting Strength to 0 bypasses the filter’s automatic sampling altogether, allowing
you to manually sample a range of color using the Refine Key tools.
•
Jump to Sample: Use these left and right arrow buttons to navigate to frames that have been
manually sampled using the Sample Color and Edges tools. When the playhead is at a sampled
frame, a numeric counter to the right of these buttons indicates your current position in the
range of sampled frames (for example, “3 of 5”).
•
View: Use these buttons to switch between three keying preview modes in the Canvas,
useful for refining your key. The View setting affects what is rendered in your final output. For
example, setting View to Matte lets you export a grayscale matte image that you can use as a
luma channel matte in another application. There are three buttons:
Matte
Original Composite
•
Composite: When selected, the leftmost button displays the final composited image in the
Canvas, with the keyed foreground object isolated against a transparent background, which
lets layers underneath show through.
•
Matte: When selected, the middle button displays the grayscale matte, or alpha channel,
generated by the keying operation. Viewing the alpha channel directly lets you evaluate
the parts of the generated matte. Areas in the matte that appear white are visible in the
final composite; areas that appear black are transparent; and areas with shades of gray are
semitransparent (lighter grays being more solid, and darker grays being more). Viewing the
alpha channel makes it easier to spot unwanted holes in the key, or areas of the key that
aren’t transparent enough.
•
Original: When selected, the rightmost button displays the original, unkeyed image in the
Canvas. This view is useful to sample colors from the original image.
67% resize factor