dulux conversion

Hi all,

I was wondering if anybody has info on converting Dulux colour to RADIANCE
RGB or some other system.

Example: 50RR 19/203

with 50RR: hue, 19: LRV (light reflectance value), 203: chroma.

Dulux seem to have changed their colour notation recently. It used to be
somewhat similar to NCS, but it's different now. The info on the pack of
swatches I have here lists the hues as:

RR: Magenta through to Red
YR: Red through to Orange
YY: Orange through to Green
GY: Green through to Turquoise
BG: Turquoise through to Blue
BB: Blue through to Violet
RB: Violet through to Magenta

If I assume that lime is 1/2 Y with 1/2 G on the NCS circle, violet is 1/3
blue with 2/3 red, and magenta is 2/3 blue with 1/3 red, then YY would
cover a whopping 90 deg on the NCS hue circle, but BB, RB, and RR only 30
deg. That doesn't look right.

A (not particularly accurate) representation of the NCS circle is in
chapter 1, page 29 of SynthLight:

Dulux have also changed the chroma part of their notation from 2 to 3 digits.

Thanks for your time.