TYPE: COP
TITLE: Chromakey COP

This COP is used to mask or "key" an image based on its color. The colors
keyed lie in the hue range, the saturation range and the luminance range
specified. Each rolloff region extends one of the ranges with a soft rolloff
function (linear, ease in, ease out, ease in ease out and Gaussian).

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 color can be picked on the image
by following the blue prompts.

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

Parameters
    Hue/Saturation    - The hue and saturation ranges of colors to key. 
			The color wheel shows the key selection.
    Luminance         - Defines the luminance range of the colors to key.
    Discard Keyed Region - If on, the keyed region is masked out (black).
			   Otherwise the rest of the image is masked out.
    Hue Rolloff       - Specifies the sharpness of the hue cutoff.
			This extends the hue range on either side
			by the rolloff size.
    Saturation Rolloff - Specifies the sharpness of the saturation cutoff.
    Luminance Rolloff - Specifies the sharpness of the luminance cutoff.
    Rolloff Function  - Specifies the rolloff function of the rolloff
			regions.
    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 Chromakey 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: Lumakey
