Reference Rendering Transform {spacesRGB}

Reference Rendering Transform

Description

The fixed RRT.TF corresponds to the RRT in aces-dev 1.1.
A parameterized version general.RRT() is also provided - for experimentation. This one returns a TransferFunction with the argument values "locked-in".

Usage

RRT.TF
general.RRT( glowmod="1.1", redmod="1.1" )

Arguments

glowmod

the version of the Glow Modifier to use. The only version currently supported is "1.1".
glowmod can also be NULL, NA, or FALSE, which means to use no Glow Modifier at all.

redmod

the version of the Red Modifier to use. The only version currently supported is "1.1". This string can also be "1.1+pinv" which means to use a precision inverse; the forward transfer is exactly the same. This precision inverse uses an iterative root-finder, and is slower than the approximate default inverse.
redmod can also be NULL, NA, or FALSE, which means to use no Red Modifier at all.

Details

RRT.TF is a Transferfunction that maps ACES RGB to OCES RGB. Both spaces are relative to the AP1 primaries. RRT.TF is constructed by calling general.RRT() with its default arguments. The transfer is complicated; here is a summary of the steps starting with ACES RGB as input:

1. glow module (see argument glowmod)

2. red modifier (see argument redmod)

3. matrix conversion from AP0 RGB → AP1 RGB

4. clamp to non-negative RGB

5. global desaturation

6. segmented spline, applied to each channel separately

7. matrix conversion from AP1 → AP0 (now OCES RGB)

Value

general.RRT() returns a Transferfunction that maps ACES RGB to OCES RGB. The domain is [0,47000]^3 and the range is [0,10000]^3.

References

ST 2065-1:2012. SMPTE Standard - Academy Color Encoding Specification (ACES). 2013.

See Also

TransferFunction