Gamma

The Gamma element applies a gamma correction to color values.

It is an Autodesk extension to the Academy/ASC XML color transform format.

Introduced

Version 1.2.

Contains

Description. Optional, any number.
GammaParams. Required, maximum three total.
DynamicParameter. Optional, no more than one. The param attribute must be set to "DEFAULT_LOOK".

Contained By

ProcessList

Attributes

id, name, bypass, inBitDepth, outBitDepth

See Common Operator Attributes.

style

Specifies the type of power law curve. Required.

Note: The following equations assume that the input and output bit-depths are floating-point. For integers, the values are normalized to [0.0, 1.0]. In other words, the gamma and offset values stored in the CTF file do not depend on the input and output bit depths.

Value	Meaning
`"basicFwd"`	Applies the power law with the gamma value specified in the GammaParams element. The GammaParams element must not have an offset attribute.
`"basicRev"`	Applies the power law with the inverse of gamma value. The GammaParams element must not have an offset attribute.
`"moncurveFwd"`	Applies a function that has a linear segment near the origin (black) and a power-law segment at higher values. At the junction, the curve is continuous in both value and tangent. This type of curve is used in the Rec. 709, sRGB, and CIE L* equations. The GammaParams element must have an offset attribute.
`"moncurveRev"`	Applies a function that has a linear segment near the origin (black) and an inverse power-law segment at higher values. The GammaParams element must have an offset attribute.

Example

Without Offset

<ProcessList id="9e999646-3e76-4374-814c-e4c46c6438de" version="1.2">
    </Matrix>
    <Gamma inBitDepth="32f" outBitDepth="12i" style="basicRev">
        <GammaParams gamma="2.400000000000000" />
    </Gamma>
</ProcessList>

With Offset

<ProcessList id="1b86aac2-1fdb-4dd8-bc6b-54f3551b9bd4" version="1.2">
    <Gamma inBitDepth="32f" outBitDepth="32f" style="moncurveFwd">
        <GammaParams gamma="2.600000000000000" offset="0.050000" />
    </Gamma>
</ProcessList>