# coding=utf-8
# Copyright 2022 The IDEA Authors. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ------------------------------------------------------------------------------------------------
# Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved
# Copyright (c) OpenMMLab. All rights reserved.
# ------------------------------------------------------------------------------------------------
# Modified from:
# https://github.com/facebookresearch/detr/blob/main/models/segmentation.py
# https://github.com/open-mmlab/mmdetection/blob/master/mmdet/models/losses/dice_loss.py
# ------------------------------------------------------------------------------------------------
import torch
import torch.nn as nn
from .utils import weight_reduce_loss
[docs]def dice_loss(
preds,
targets,
weight=None,
eps: float = 1e-4,
reduction: str = "mean",
avg_factor: int = None,
):
"""
Compute the DICE loss, similar to generalized IOU for masks
Args:
preds (torch.Tensor): A float tensor of arbitrary shape.
The predictions for each example.
targets (torch.Tensor):
A float tensor with the same shape as inputs. Stores the binary
classification label for each element in inputs
(0 for the negative class and 1 for the positive class).
weight (torch.Tensor, optional): The weight of loss for each
prediction, has a shape (n,). Defaults to None.
eps (float): Avoid dividing by zero. Default: 1e-4.
avg_factor (int, optional): Average factor that is used to average
the loss. Default: None.
Return:
torch.Tensor: The computed dice loss.
"""
preds = preds.flatten(1)
targets = targets.flatten(1).float()
numerator = 2 * torch.sum(preds * targets, 1) + eps
denominator = torch.sum(preds, 1) + torch.sum(targets, 1) + eps
loss = 1 - (numerator + 1) / (denominator + 1)
if weight is not None:
assert weight.ndim == loss.ndim
assert len(weight) == len(preds)
loss = weight_reduce_loss(loss, weight, reduction, avg_factor)
return loss
class DiceLoss(nn.Module):
def __init__(
self,
use_sigmoid=True,
reduction="mean",
loss_weight=1.0,
eps=1e-3,
):
super(DiceLoss, self).__init__()
self.use_sigmoid = use_sigmoid
self.reduction = reduction
self.loss_weight = loss_weight
self.eps = eps
def forward(
self,
preds,
targets,
weight=None,
avg_factor=None,
):
if self.use_sigmoid:
preds = preds.sigmoid()
loss = self.loss_weight * dice_loss(
preds,
targets,
weight,
eps=self.eps,
reduction=self.reduction,
avg_factor=avg_factor,
)
return loss