I have the following code for gamma correcting a reflectance value. For example, if the reflectance is 18% (0.18) and the gamma is 0.45, this gives me a value of 40.9. The 40.9 value agrees with everything I've read.
The question is, what is the math to convert this to IRE units? I am expecting to see a value of 43.4 according to everything I've read.
If I change the reflectance to 90% as found on a typical test chart:
I get a value of 94.9. I believe this is correct. After conversion to IRE units it should be 100.
What is the correct way to convert these gamma-corrected numbers based on reflectance to IRE units?