Cross Entropy
CE(pt)=−(y⋅log2(pt)+(1−y)⋅log2(1−pt))
Focal Loss (RetinaNet)
- γ: 2
- α: 0.25
FL(pt)=−(y⋅α⋅(1−pt)γ⋅log2(pt)+(1−y)⋅(1−α)⋅ptγ⋅log2(1−pt))
Focal Loss (CentetNet, CenterPoint)
FL(pt)=−(y⋅(1−pt)2⋅log2(pt)+(1−y)4⋅ptγ⋅log2(1−pt))