Converting a Given Color Phase to I and Q

[ColecoFan1981]

I'm wondering what the proper formula might be in regards to converting a given color phase angle to the signals I and Q that I could then convert to RGB along with Y' (luminance)?

 

For example, Medium Green as represented by the Texas Instruments TMS9918A VDP has a luminance value of 0.47 (Y') and a phase angle of 204 (actually 237, but minus 33 degrees). What I want to know is how to obtain I and Q from the 204.

 

The TMS9118/9128/9129 datasheet does list additional information like A' which refers to the square root of the sum of the squares of E'I and E'Q, both of which represent gamma-corrected I and Q signals, which respectively are the orange-cyan and magenta-green axis signals placed 33 degrees ahead of the E'R and E'Y (orange-cyan) and E'B and E'Y (magenta-green) signals.

 

Thank you,

 

 

 

Ben

Edited March 1, 2016 by ColecoFan1981