Dice Similarity Coefficient Calculation

Hello,

I am trying to use the Dice coeffcient in matlab to compare two segmentation images. I was wondering how the dice coefficient is actually calculated?

This is the function I'm talking about: https://www.mathworks.com/help/images/ref/dice.html#mw_2541c8d5-94e0-420d-a77f-2c726ba38816

How does it calculate the true positives and false negatives etc.?