Meaning of Contrast


I have quite a scpecific question concerning the Tone Response Curves formula :

Luminance = Contrast x (value)^(gamma) + black level[/code]

I have a good idea of what the black leve term means, but I have more problems with the Contrast term : does it correspond to the contrast given by the formula [code]
(Lmax-Lmin) / Lmin

or is it calculated in an other way?

I have some measures I have tried to match using these equations, but it did not work properly.

I would be very thankful if someone could help me a bit, because I can’t seem to find the answer on the internet

Thanks in advance.