pub unsafe static kCVImageBufferLogTransferFunctionKey: &'static CFStringCVImageBuffer only.Expand description
Indicates that the transfer function or gamma of the content is a log format and identifies the specific log curve.
The value is a CFString holding fully specified reverse DNS identifier. Log is a specific video format usually processed in a camera’s ISP. A Log video format usually defines: Scene-referred color primaries designed to preserve the chromaticity range captured by a camera sensor. In cinematography, “scene-referred” color primaries refers to a color space designed to accurately preserve the chromaticity and dynamic range directly captured by a camera sensor. A specific gamma curve (or transfer characteristic) tailored to capturing the full dynamic range from the sensor. This gamma curve is usually shaped like a log curve (hence the name Log). A set of matrix transforms to go from RGB to Y’CbCr (Y’CbCr being the most common format used to store the bits compressed into a file). As described above, a Log video format defines a whole color space (even though the “log” part of the name comes only from the “transfer characteristic” or gamma curve) Content captured in Apple Log will have this key set to kCVImageBufferLogTransferFunction_AppleLog or kCVImageBufferLogTransferFunction_AppleLog2.
Indicates the Apple Log identifier.
Indicates the Apple Log 2 identifier. To use Apple Log 2, set other color attachments as follows: kCVImageBufferColorPrimariesKey = undefined or absent kCVImageBufferTransferFunctionKey = undefined or absent kCVImageBufferYCbCrMatrixKey = kCVImageBufferYCbCrMatrix_ITU_R_2020 https://developer.apple.com/download/all/?q=Apple%20log%20profile
You can download the Apple Log Profile White Paper from the Apple Developer Downloads website.
See also Apple’s documentation