A dataframe or matrix with X, Y and Z colour channels located in the columns 1 to 3, respectively.
transformation
An option in c("sRGB", "Adobe") for a built-in transformation or, alternatively, a custom 3x3 transformation matrix.
linear_func
A function to convert linear RGB colour space into RGB space. Used only if a custom transformation matrix is provided. Transformation skips if no function is provided under a user-defined transformation matrix. See: https://en.wikipedia.org/wiki/SRGB.