# Source code for catalyst.contrib.nn.criterion.wing

from functools import partial
import math
import torch
from torch import nn
def wing_loss(
outputs: torch.Tensor,
targets: torch.Tensor,
width: int = 5,
curvature: float = 0.5,
reduction: str = "mean",
) -> torch.Tensor:
"""The Wing loss.
It has been proposed in `Wing Loss for Robust Facial Landmark Localisation
with Convolutional Neural Networks`_.
Args:
@TODO: Docs. Contribution is welcome.
Main origins of inspiration:
https://github.com/BloodAxe/pytorch-toolbelt (MIT License)
.. _Wing Loss for Robust Facial Landmark Localisation with Convolutional
Neural Networks: https://arxiv.org/abs/1711.06753
"""
diff_abs = (targets - outputs).abs()
loss = diff_abs.clone()
idx_smaller = diff_abs < width
idx_bigger = diff_abs >= width
loss[idx_smaller] = width * torch.log(
1 + diff_abs[idx_smaller] / curvature
)
c = width - width * math.log(1 + width / curvature)
loss[idx_bigger] = loss[idx_bigger] - c
if reduction == "sum":
loss = loss.sum()
if reduction == "mean":
loss = loss.mean()
return loss
[docs]class WingLoss(nn.Module):
"""Creates a criterion that optimizes a Wing loss.
It has been proposed in `Wing Loss for Robust Facial Landmark Localisation
with Convolutional Neural Networks`_.
Examples:
@TODO: Docs. Contribution is welcome.
Main origins of inspiration:
https://github.com/BloodAxe/pytorch-toolbelt
.. _Wing Loss for Robust Facial Landmark Localisation with Convolutional
Neural Networks: https://arxiv.org/abs/1711.06753
"""
[docs] def __init__(
self, width: int = 5, curvature: float = 0.5, reduction: str = "mean"
):
"""
Args:
@TODO: Docs. Contribution is welcome.
"""
super().__init__()
self.loss_fn = partial(
wing_loss, width=width, curvature=curvature, reduction=reduction
)
[docs] def forward(
self, outputs: torch.Tensor, targets: torch.Tensor
) -> torch.Tensor:
"""
Args:
@TODO: Docs. Contribution is welcome.
"""
loss = self.loss_fn(outputs, targets)
return loss
__all__ = ["WingLoss"]