image-match/python/py/Lib/site-packages/kornia/feature/tfeat.py

# LICENSE HEADER MANAGED BY add-license-header
#
# Copyright 2018 Kornia Team
#
# 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.
#

from typing import Dict

import torch
from torch import nn

from kornia.core.check import KORNIA_CHECK_SHAPE

urls: Dict[str, str] = {}
urls["liberty"] = "https://github.com/vbalnt/tfeat/raw/master/pretrained-models/tfeat-liberty.params"  # pylint: disable
urls["notredame"] = "https://github.com/vbalnt/tfeat/raw/master/pretrained-models/tfeat-notredame.params"  # pylint: disable
urls["yosemite"] = "https://github.com/vbalnt/tfeat/raw/master/pretrained-models/tfeat-yosemite.params"  # pylint: disable


class TFeat(nn.Module):
    r"""Module, which computes TFeat descriptors of given grayscale patches of 32x32.

    This is based on the original code from paper "Learning local feature descriptors
    with triplets and shallow convolutional neural networks".
    See :cite:`TFeat2016` for more details

    Args:
        pretrained: Download and set pretrained weights to the model.

    Returns:
        torch.Tensor: TFeat descriptor of the patches.

    Shape:
        - Input: :math:`(B, 1, 32, 32)`
        - Output: :math:`(B, 128)`

    Examples:
        >>> input = torch.rand(16, 1, 32, 32)
        >>> tfeat = TFeat()
        >>> descs = tfeat(input) # 16x128

    """

    patch_size = 32

    def __init__(self, pretrained: bool = False) -> None:
        super().__init__()
        self.features = nn.Sequential(
            nn.InstanceNorm2d(1, affine=False),
            nn.Conv2d(1, 32, kernel_size=7),
            nn.Tanh(),
            nn.MaxPool2d(kernel_size=2, stride=2),
            nn.Conv2d(32, 64, kernel_size=6),
            nn.Tanh(),
        )
        self.descr = nn.Sequential(nn.Linear(64 * 8 * 8, 128), nn.Tanh())
        # use torch.hub to load pretrained model
        if pretrained:
            pretrained_dict = torch.hub.load_state_dict_from_url(urls["liberty"], map_location=torch.device("cpu"))
            self.load_state_dict(pretrained_dict, strict=True)
        self.eval()

    def forward(self, input: torch.Tensor) -> torch.Tensor:
        KORNIA_CHECK_SHAPE(input, ["B", "1", "32", "32"])
        x = self.features(input)
        x = x.view(x.size(0), -1)
        x = self.descr(x)
        return x