How to get gamma of image in HSI color space

Question

I am required to change Gamma of a photo using HSI color space. I changed RGB to HSI color space and know that I need to change the intensity with Gamma value. But I don't know how to find gamma value of the image since HSI is just hue,saturation and intensity. Anyone know how I can find Gamma value? I hardly can find anything online.

Answer 1

There is no such thing as "gamma value of the image". What you were required is to change the curve of the tone mapping, which is frequently called gamma, due to historical reasons.

In order to do this, use some sort of monotonically rising curve that is applied on the I channel, or on R, G and B together. The most used example is to use a power function -> y=x^(p), where p is a parameter. (To make things more confusive, p is often called gamma as well.)