In the neutral-plus file that comes with dcamprof (actually I may have copied it over from the files in Lumariver profile designer) it describes using custom gamuts. The example given (shown below) is for AdobeRGB. However, it refers to the given matrix as an RGB to XYZ matrix. It’s not an RGB to XYZ matrix, though. What’s actually shown is an XYZ to RGB matrix.
So, either the words “RGB to XYZ” are mistaken, and it was meant to read “XYZ to RGB”, or the matrix shown is incorrect. I emailed Anders Torger several months ago and he said that it had been a few years since he’s done anything with dcamprof and didn’t remember. I was going to make a custom look tonight and remembered this, so figured I’d ask here.
When I substitute the matrix for its inverse, I don’t really see a difference in the resulting profile so maybe dcamprof detects if the matrix needs to be inverted?
// Just for demonstration of the custom matrix feature we specify AdobeRGB with its RGB to XYZ matrix
// instead of using the "AdobeRGB" shortcut. The matrix which will automatically be remapped to D50
// whitepoint (AdobeRGB is D65).
//"InnerGamut": "AdobeRGB",
"InnerGamut": [
[ 2.04159, -0.56501, -0.34473 ],
[ -0.96924, 1.87597, 0.04156 ],
[ 0.01344, -0.11836, 1.01517 ]
],