# jit.chromakey

## Description

Produces an chromakey effect based on a reference color. Tolerance and fade settings allow for control over the resulting combined image. An alternate mode outputs a matrix with the keying values, which can be used by other Jitter objects.

## Examples

## Discussion

The jit.chromakey object measures the chromatic distance of each of the left input's cells (pixels) with a reference color (a.k.a "green screening"). The total chromatic distance is calculated by summing the absolute value of each color channel's distance from the reference color's corresponding color channel.

If the distance is less than or equal to a tolerated distance (

) value, the right input cell is multiplied by a maximum keying ( ) value.If the distance is greater than the tolerated distance but less than the sum of the tolerated value and a set fade value (

) an interpolated value between the some value between and 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

value.The left input is always multiplied by the additive inverse of the left input's multiplicand.

The jit.chromakey 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 and values.

## Matrix Operator

Name | IOProc | Planelink | Typelink | Dimlink | Plane | Dim | Type |
---|---|---|---|---|---|---|---|

in2 | resamp | 1 | 1 | 1 | 1 | 1 | char long float32 float64 |

out | n/a | 1 | 1 | 1 | 1 | 1 | char long float32 float64 |

### More about Matrix Operators

### The Jitter MOP

### MOP Arguments

### MOP Attributes

### MOP Messages

## Attributes

### alphaignore [int]

Ignore alpha channel flag (default = 1)

0 = use alpha channel (plane 0) when calculating chromatic distance

1 = ignore alpha channel (plane 0) when calculating chromatic distance

### color [32 floats]

The reference color to be used for keying (default = all 0.)

### fade [float]

The amount of fade (default = 0.)

### maxkey [float]

The maximum keying value (default = 1.)

### minkey [float]

Minimum keying value

### mode [int]

Output mode (default = 0)

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

Possible values:

0 = 'Composite'

1 = 'Key Map in All Channels'

2 = 'Key Map in Alpha'

### tol [float]

The tolerated distance -- the range of variance from which an input cell's absolute value can diverge when calculating keying (default = 0.)

### Common Box Attributes

## See Also

Name | Description |
---|---|

Working with Video in Jitter | Working with Video in Jitter |

jit.alphablend | |

jit.keyscreen | |

jit.lumakey | |

jit.op | |

Tutorial 10: Chromakeying | Tutorial 10: Chromakeying |