Key based on distance from a luminance value
If the distance is less than or equal to a tolerated distance ( tol ) value, the right input cell is multiplied by a maximum keying ( maxkey ) value.
If the distance is greater than the tolerated distance but less than the sum of the tolerated value and a set fade value ( fade ) an interpolated value between the some value between minkey and maxkey values is applied.
For values whose distance is greater than the sum of the tolerated and fade values, the right input cell is multiplied by the minkey value.
The left input is always multiplied by the additive inverse of the left input's multiplicand.
The jit.lumakey object has two modes of output; the first keys between the two input sources, and the second mode will output the keying values (i.e., the left input multiplicands) rather than applying the keying  the left input is ignored. This is useful for outputting keying information for use with other Jitter objects. Keying can be inverted by swapping the minkey and maxkey values.
Name  IOProc  Planelink  Typelink  Dimlink  Plane  Dim  Type 
in2  resamp  1  1  1  4  1  char long float32 float64 
out  n/a  1  1  1  4  1  char long float32 float64 
Name  Type  g/s  Description 

ascale  float  The alpha scaling factor (default = 0.)  
bscale  float  The blue scaling factor (default = 0.114)  
fade  float  Amount of fade (default = 0.)  
gscale  float  The green scaling factor (default = 0.587)  
lum  float  The reference luminance (default = all 0.)  
maxkey  float  The maximum keying (  ) value (default = 1.)
minkey  float  The minimum keying (  ) value (default = 0.)
mode  int  Output mode (default = 0 (output keyed matrix)) 0 = perform keying and output matrix 1 = output the key map for use elsewhere 2 = alpha contains key map, other planes are from left input 

rscale  float  The red scaling factor (default = 0.299)  
tol  float  The tolerated distance (  )  the range of variance from which an input cell's absolute value can diverge when calculating keying (default = 0.)
Name  Description 

jit.alphablend  Use the alpha channel of one image to blend two images together 
jit.chromakey  Keying based on chromatic distance 
jit.keyscreen  Choke chromakey 3 sources 
jit.rgb2luma  Converts RGB to monochrome (luminance) 