Log

The Log operator applies a logarithmic or anti-logarithmic function to convert between linear and Cineon-style encodings.

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

Introduced

Version 1.3.

Contains

Description. Optional, any number.
LogParams. Required if the style attribute is "logToLin" or "linToLog". There should be one occurence for values applied to all RGB channels, or three occurences for different values applied to R, G, and B separately.
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 formula to use for the conversion. 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, reference white, reference black, highlight, and shadow values stored in the CTF file do not depend on the input and output bit depths.

In the following equations:

Value	Meaning
`"log10"`
`"log2"`
`"antiLog10"`
`"antiLog2"`
`"logToLin"`
`"linToLog"`

Example

All Channels

<ProcessList id="19510ea6-69a0-4d3d-bc75-d0b36d458f62" name="Log op 1" version="1.3">
     <Log inBitDepth="16f" outBitDepth="12i" style="linToLog">
        <LogParams gamma="0.6" refWhite="685" refBlack="95" highlight="1.0" shadow="0.0005"/>
    </Log>
</ProcessList>

Separate Channels

<ProcessList id="19510ea6-69a0-4d3d-bc75-d0b36d458f62" name="Log op 1" version="1.3">
     <Log inBitDepth="16f" outBitDepth="12i" style="linToLog">
        <LogParams channel="R" gamma="0.5" refWhite="685" refBlack="95" highlight="1.0" shadow="0.0005"/>
        <LogParams channel="G" gamma="0.6" refWhite="685" refBlack="95" highlight="1.0" shadow="0.0005"/>
        <LogParams channel="B" gamma="0.65" refWhite="685" refBlack="95" highlight="1.0" shadow="0.0005"/>
    </Log>
</ProcessList>