TYPE: COP
TITLE: Lumakey COP

This operation masks or "keys" the image based on luminance (or similar 
function). All colors with a luminance that lies within the keyed range
are masked. Both the upper and lower luminance range can be toggled off, in
which case the luminance is not clamped at any minimum or maximum value.

The key plane is used to determine the areas of the image to mask. The mask
is then applied to all scoped planes, including the key plane (if it is 
scoped). Normally this key plane is color. The luminance can be picked on the
image by following the blue prompts.

Middle click on the dialog '?' help for more help on maskable operations.

Parameters
    Min Luminance        - If on, this sets the lower limit for the key.
    Max Luminance        - If on, this sets the upper limit for the key.
    Discard Keyed Region - If on, the keyed region is discarded.
    Rolloff Region       - The size of the rolloff region, in case a
			   sharp edge is not wanted. This extends the
			   keyed range by the rolloff size with a soft
			   function.
    Rolloff Function     - Specifies the rolloff function of the rolloff
			   region.
    Luminance Function   - Specifies how to prep the color to key off.
    Supersample          - The number of subpixels sampled per pixel in one
			   direction (2 samples 4 pixels, 3 samples 9). 
			   More subsamples produce finer edges, at the
			   cost of performance.
    Key Plane            - Specifies the plane to key. All scoped planes
			   will be masked based on the result of the
			   lumakey on this plane.

Mask & Plane Scope, Frame Scope page:
    Overview - See extra help (Middle click on the dialog '?' help).

Local Variables:
    L   - Sequence length
    S   - Start of sequence
    E   - End of sequence
    IL  - Input sequence length
    SR  - Sequence frame rate
    NP  - Number of planes in sequence
    W,H - Width and height of image
    I   - Image index (0 at start frame)
    IT  - Image time (0 at start frame)
    AI  - Current plane array index
    PI  - Current plane index
    PC  - Num of channels in current plane

See Also: Chromakey, Screenkey
