According to this note, Frostbite use photometry unit in their calculation. I am trying to mimic this feature, but I am not sure what transformation need to be done. I will try to explain what I have in mind.
First we do gamma correction(pow(2.2)) to the albedo texture. Then we apply the BRDF that takes luminance as input and will produce output luminance. After that we do tonemapping(say we use filmic tone mapping) and then inverse gamma correct pow(1/2.2) and store it to the framebuffer.
Is this process correct? Should I transform the luminance to radiance first before doing the tonemap or maybe I should convert it even before that when doing BRDF calculation? Do I need to convert the albedo with photometry curve after doing gamma correction?