[D] Focal loss - why it scales down the loss of minority class?

The equation of α-balanced focal loss (binary in this case for simplicity) is given by:

https://preview.redd.it/39hgb62728r91.png?width=718&format=png&auto=webp&s=8064189fe0dcd7dc4a04b24bd8acc837d12240ea

What puzzles me is that it seems like weighing used here is opposite to what is intuitive when dealing with imbalanced datasets: normally you would scale the loss of class 1 (minority - foreground objects in case of object detection) higher than the class 0 (majority - background). However what happens here is that we scale class 1 by 0.25, and class 0 by …

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