354 lines
13 KiB
Python
354 lines
13 KiB
Python
# Copyright 2018 The TensorFlow Authors. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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# ==============================================================================
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# pylint: disable=invalid-name
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# pylint: disable=unused-import
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"""DenseNet models for Keras.
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# Reference paper
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- [Densely Connected Convolutional Networks]
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(https://arxiv.org/abs/1608.06993) (CVPR 2017 Best Paper Award)
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"""
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from __future__ import absolute_import
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from __future__ import division
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from __future__ import print_function
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import os
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from tensorflow.python.keras import backend as K
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from tensorflow.python.keras.applications import imagenet_utils
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from tensorflow.python.keras.applications.imagenet_utils import _obtain_input_shape
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from tensorflow.python.keras.applications.imagenet_utils import decode_predictions
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from tensorflow.python.keras.layers import Activation
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from tensorflow.python.keras.layers import AveragePooling2D
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from tensorflow.python.keras.layers import BatchNormalization
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from tensorflow.python.keras.layers import Concatenate
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from tensorflow.python.keras.layers import Conv2D
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from tensorflow.python.keras.layers import Dense
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from tensorflow.python.keras.layers import GlobalAveragePooling2D
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from tensorflow.python.keras.layers import GlobalMaxPooling2D
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from tensorflow.python.keras.layers import Input
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from tensorflow.python.keras.layers import MaxPooling2D
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from tensorflow.python.keras.layers import ZeroPadding2D
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from tensorflow.python.keras.models import Model
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from tensorflow.python.keras.utils import layer_utils
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from tensorflow.python.keras.utils.data_utils import get_file
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from tensorflow.python.util.tf_export import tf_export
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DENSENET121_WEIGHT_PATH = 'https://github.com/fchollet/deep-learning-models/releases/download/v0.8/densenet121_weights_tf_dim_ordering_tf_kernels.h5'
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DENSENET121_WEIGHT_PATH_NO_TOP = 'https://github.com/fchollet/deep-learning-models/releases/download/v0.8/densenet121_weights_tf_dim_ordering_tf_kernels_notop.h5'
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DENSENET169_WEIGHT_PATH = 'https://github.com/fchollet/deep-learning-models/releases/download/v0.8/densenet169_weights_tf_dim_ordering_tf_kernels.h5'
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DENSENET169_WEIGHT_PATH_NO_TOP = 'https://github.com/fchollet/deep-learning-models/releases/download/v0.8/densenet169_weights_tf_dim_ordering_tf_kernels_notop.h5'
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DENSENET201_WEIGHT_PATH = 'https://github.com/fchollet/deep-learning-models/releases/download/v0.8/densenet201_weights_tf_dim_ordering_tf_kernels.h5'
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DENSENET201_WEIGHT_PATH_NO_TOP = 'https://github.com/fchollet/deep-learning-models/releases/download/v0.8/densenet201_weights_tf_dim_ordering_tf_kernels_notop.h5'
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def dense_block(x, blocks, name):
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"""A dense block.
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Arguments:
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x: input tensor.
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blocks: integer, the number of building blocks.
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name: string, block label.
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Returns:
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output tensor for the block.
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"""
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for i in range(blocks):
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x = conv_block(x, 32, name=name + '_block' + str(i + 1))
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return x
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def transition_block(x, reduction, name):
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"""A transition block.
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Arguments:
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x: input tensor.
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reduction: float, compression rate at transition layers.
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name: string, block label.
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Returns:
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output tensor for the block.
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"""
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bn_axis = 3 if K.image_data_format() == 'channels_last' else 1
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x = BatchNormalization(axis=bn_axis, epsilon=1.001e-5, name=name + '_bn')(x)
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x = Activation('relu', name=name + '_relu')(x)
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x = Conv2D(
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int(K.int_shape(x)[bn_axis] * reduction),
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1,
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use_bias=False,
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name=name + '_conv')(
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x)
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x = AveragePooling2D(2, strides=2, name=name + '_pool')(x)
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return x
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def conv_block(x, growth_rate, name):
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"""A building block for a dense block.
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Arguments:
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x: input tensor.
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growth_rate: float, growth rate at dense layers.
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name: string, block label.
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Returns:
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output tensor for the block.
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"""
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bn_axis = 3 if K.image_data_format() == 'channels_last' else 1
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x1 = BatchNormalization(
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axis=bn_axis, epsilon=1.001e-5, name=name + '_0_bn')(
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x)
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x1 = Activation('relu', name=name + '_0_relu')(x1)
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x1 = Conv2D(4 * growth_rate, 1, use_bias=False, name=name + '_1_conv')(x1)
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x1 = BatchNormalization(
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axis=bn_axis, epsilon=1.001e-5, name=name + '_1_bn')(
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x1)
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x1 = Activation('relu', name=name + '_1_relu')(x1)
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x1 = Conv2D(
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growth_rate, 3, padding='same', use_bias=False, name=name + '_2_conv')(
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x1)
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x = Concatenate(axis=bn_axis, name=name + '_concat')([x, x1])
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return x
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def DenseNet(blocks,
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include_top=True,
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weights='imagenet',
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input_tensor=None,
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input_shape=None,
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pooling=None,
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classes=1000):
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"""Instantiates the DenseNet architecture.
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Optionally loads weights pre-trained
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on ImageNet. Note that when using TensorFlow,
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for best performance you should set
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`image_data_format='channels_last'` in your Keras config
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at ~/.keras/keras.json.
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The model and the weights are compatible with
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TensorFlow, Theano, and CNTK. The data format
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convention used by the model is the one
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specified in your Keras config file.
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Arguments:
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blocks: numbers of building blocks for the four dense layers.
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include_top: whether to include the fully-connected
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layer at the top of the network.
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weights: one of `None` (random initialization),
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'imagenet' (pre-training on ImageNet),
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or the path to the weights file to be loaded.
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input_tensor: optional Keras tensor (i.e. output of `layers.Input()`)
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to use as image input for the model.
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input_shape: optional shape tuple, only to be specified
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if `include_top` is False (otherwise the input shape
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has to be `(224, 224, 3)` (with `channels_last` data format)
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or `(3, 224, 224)` (with `channels_first` data format).
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It should have exactly 3 inputs channels.
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pooling: optional pooling mode for feature extraction
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when `include_top` is `False`.
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- `None` means that the output of the model will be
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the 4D tensor output of the
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last convolutional layer.
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- `avg` means that global average pooling
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will be applied to the output of the
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last convolutional layer, and thus
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the output of the model will be a 2D tensor.
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- `max` means that global max pooling will
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be applied.
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classes: optional number of classes to classify images
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into, only to be specified if `include_top` is True, and
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if no `weights` argument is specified.
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Returns:
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A Keras model instance.
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Raises:
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ValueError: in case of invalid argument for `weights`,
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or invalid input shape.
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"""
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if not (weights in {'imagenet', None} or os.path.exists(weights)):
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raise ValueError('The `weights` argument should be either '
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'`None` (random initialization), `imagenet` '
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'(pre-training on ImageNet), '
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'or the path to the weights file to be loaded.')
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if weights == 'imagenet' and include_top and classes != 1000:
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raise ValueError('If using `weights` as imagenet with `include_top`'
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' as true, `classes` should be 1000')
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# Determine proper input shape
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input_shape = _obtain_input_shape(
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input_shape,
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default_size=224,
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min_size=221,
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data_format=K.image_data_format(),
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require_flatten=include_top,
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weights=weights)
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if input_tensor is None:
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img_input = Input(shape=input_shape)
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else:
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if not K.is_keras_tensor(input_tensor):
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img_input = Input(tensor=input_tensor, shape=input_shape)
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else:
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img_input = input_tensor
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bn_axis = 3 if K.image_data_format() == 'channels_last' else 1
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x = ZeroPadding2D(padding=((3, 3), (3, 3)))(img_input)
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x = Conv2D(64, 7, strides=2, use_bias=False, name='conv1/conv')(x)
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x = BatchNormalization(axis=bn_axis, epsilon=1.001e-5, name='conv1/bn')(x)
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x = Activation('relu', name='conv1/relu')(x)
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x = ZeroPadding2D(padding=((1, 1), (1, 1)))(x)
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x = MaxPooling2D(3, strides=2, name='pool1')(x)
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x = dense_block(x, blocks[0], name='conv2')
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x = transition_block(x, 0.5, name='pool2')
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x = dense_block(x, blocks[1], name='conv3')
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x = transition_block(x, 0.5, name='pool3')
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x = dense_block(x, blocks[2], name='conv4')
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x = transition_block(x, 0.5, name='pool4')
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x = dense_block(x, blocks[3], name='conv5')
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x = BatchNormalization(axis=bn_axis, epsilon=1.001e-5, name='bn')(x)
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if include_top:
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x = GlobalAveragePooling2D(name='avg_pool')(x)
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x = Dense(classes, activation='softmax', name='fc1000')(x)
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else:
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if pooling == 'avg':
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x = GlobalAveragePooling2D(name='avg_pool')(x)
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elif pooling == 'max':
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x = GlobalMaxPooling2D(name='max_pool')(x)
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# Ensure that the model takes into account
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# any potential predecessors of `input_tensor`.
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if input_tensor is not None:
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inputs = layer_utils.get_source_inputs(input_tensor)
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else:
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inputs = img_input
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# Create model.
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if blocks == [6, 12, 24, 16]:
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model = Model(inputs, x, name='densenet121')
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elif blocks == [6, 12, 32, 32]:
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model = Model(inputs, x, name='densenet169')
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elif blocks == [6, 12, 48, 32]:
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model = Model(inputs, x, name='densenet201')
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else:
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model = Model(inputs, x, name='densenet')
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# Load weights.
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if weights == 'imagenet':
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if include_top:
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if blocks == [6, 12, 24, 16]:
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weights_path = get_file(
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'densenet121_weights_tf_dim_ordering_tf_kernels.h5',
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DENSENET121_WEIGHT_PATH,
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cache_subdir='models',
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file_hash='0962ca643bae20f9b6771cb844dca3b0')
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elif blocks == [6, 12, 32, 32]:
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weights_path = get_file(
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'densenet169_weights_tf_dim_ordering_tf_kernels.h5',
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DENSENET169_WEIGHT_PATH,
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cache_subdir='models',
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file_hash='bcf9965cf5064a5f9eb6d7dc69386f43')
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elif blocks == [6, 12, 48, 32]:
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weights_path = get_file(
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'densenet201_weights_tf_dim_ordering_tf_kernels.h5',
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DENSENET201_WEIGHT_PATH,
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cache_subdir='models',
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file_hash='7bb75edd58cb43163be7e0005fbe95ef')
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else:
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if blocks == [6, 12, 24, 16]:
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weights_path = get_file(
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'densenet121_weights_tf_dim_ordering_tf_kernels_notop.h5',
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DENSENET121_WEIGHT_PATH_NO_TOP,
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cache_subdir='models',
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file_hash='4912a53fbd2a69346e7f2c0b5ec8c6d3')
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elif blocks == [6, 12, 32, 32]:
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weights_path = get_file(
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'densenet169_weights_tf_dim_ordering_tf_kernels_notop.h5',
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DENSENET169_WEIGHT_PATH_NO_TOP,
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cache_subdir='models',
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file_hash='50662582284e4cf834ce40ab4dfa58c6')
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elif blocks == [6, 12, 48, 32]:
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weights_path = get_file(
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'densenet201_weights_tf_dim_ordering_tf_kernels_notop.h5',
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DENSENET201_WEIGHT_PATH_NO_TOP,
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cache_subdir='models',
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file_hash='1c2de60ee40562448dbac34a0737e798')
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model.load_weights(weights_path)
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elif weights is not None:
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model.load_weights(weights)
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return model
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@tf_export('keras.applications.DenseNet121',
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'keras.applications.densenet.DenseNet121')
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def DenseNet121(include_top=True,
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weights='imagenet',
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input_tensor=None,
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input_shape=None,
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pooling=None,
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classes=1000):
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return DenseNet([6, 12, 24, 16], include_top, weights, input_tensor,
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input_shape, pooling, classes)
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@tf_export('keras.applications.DenseNet169',
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'keras.applications.densenet.DenseNet169')
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def DenseNet169(include_top=True,
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weights='imagenet',
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input_tensor=None,
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input_shape=None,
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pooling=None,
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classes=1000):
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return DenseNet([6, 12, 32, 32], include_top, weights, input_tensor,
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input_shape, pooling, classes)
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@tf_export('keras.applications.DenseNet201',
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'keras.applications.densenet.DenseNet201')
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def DenseNet201(include_top=True,
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weights='imagenet',
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input_tensor=None,
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input_shape=None,
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pooling=None,
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classes=1000):
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return DenseNet([6, 12, 48, 32], include_top, weights, input_tensor,
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input_shape, pooling, classes)
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@tf_export('keras.applications.densenet.preprocess_input')
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def preprocess_input(x, data_format=None):
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"""Preprocesses a numpy array encoding a batch of images.
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Arguments:
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x: a 3D or 4D numpy array consists of RGB values within [0, 255].
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data_format: data format of the image tensor.
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Returns:
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Preprocessed array.
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"""
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return imagenet_utils.preprocess_input(x, data_format, mode='torch')
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setattr(DenseNet121, '__doc__', DenseNet.__doc__)
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setattr(DenseNet169, '__doc__', DenseNet.__doc__)
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setattr(DenseNet201, '__doc__', DenseNet.__doc__)
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