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# kVTCompressionPropertyKey_LogTransferFunction

Indicates that the transfer function or gamma of the content is a log format and identifies the specific log curve.
Log curve identifiers include `kCVImageBufferLogTransferFunction_AppleLog` (“com.apple.rec2020.apple-log”)
and `kCVImageBufferLogTransferFunction_AppleLog2` (“com.apple.apple-wide-gamut.apple-log”).
When the LogTransferFunction is specified for a VTCompressionSession, if source image buffers do not have exactly that LogTransferFunction, encoding will fail.

```
let kVTCompressionPropertyKey_LogTransferFunction: CFString
```

---

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