New <Exponent> Process Node

Discussions - ACESNext VWG – Common LUT Format (CLF)
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This process node is on the list to be added to the revised spec.

The node is intended to allow for achieving both basic “gamma” curves and “moncurve” gamma curves (i.e. linear segment near black).

Needs from the group:

  • agreement on name for node
  • decision on handling of values below 0 - pass-through? mirror? linear extension? clamp?
  • valid ranges for exponent attribute
  • valid ranges for offset attribute
  • is ExponentParams separatable per channel?

As of now, this node will have sub-elements:
<Description> - (optional)
<ExponentParams> (or other name) - (required) contains the attributes exponent and offset

The node will have attribute(s):
style - specifies the type of exponent function
Options for style are "basicFwd", "basicRev", "moncurveFwd", "moncurveRev"
For style="basic", only exponent attribute is recognized and valid.

Additional styles will need to be named and defined in order to provide for different negative handling options.

What options do interested parties require?