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  • 使用keras导入densenet模型

    从keras的keras_applications的文件夹内可以找到内置模型的源代码

    Kera的应用模块Application提供了带有预训练权重的Keras模型,这些模型可以用来进行预测、特征提取和finetune

    应用于图像分类的模型,权重训练自ImageNet: Xception VGG16 VGG19 ResNet50 InceptionV3InceptionResNetV2 * MobileNet densenet

    densenet的keras源代码如下:

    """DenseNet models for Keras.
    
    # Reference paper
    
    - [Densely Connected Convolutional Networks]
      (https://arxiv.org/abs/1608.06993) (CVPR 2017 Best Paper Award)
    
    # Reference implementation
    
    - [Torch DenseNets]
      (https://github.com/liuzhuang13/DenseNet/blob/master/models/densenet.lua)
    - [TensorNets]
      (https://github.com/taehoonlee/tensornets/blob/master/tensornets/densenets.py)
    """
    from __future__ import absolute_import
    from __future__ import division
    from __future__ import print_function
    
    import os
    
    from . import get_keras_submodule
    
    backend = get_keras_submodule('backend')
    engine = get_keras_submodule('engine')
    layers = get_keras_submodule('layers')
    models = get_keras_submodule('models')
    keras_utils = get_keras_submodule('utils')
    
    from . import imagenet_utils
    from .imagenet_utils import decode_predictions
    from .imagenet_utils import _obtain_input_shape
    
    
    BASE_WEIGTHS_PATH = (
        'https://github.com/fchollet/deep-learning-models/'
        'releases/download/v0.8/')
    DENSENET121_WEIGHT_PATH = (
        BASE_WEIGTHS_PATH +
        'densenet121_weights_tf_dim_ordering_tf_kernels.h5')
    DENSENET121_WEIGHT_PATH_NO_TOP = (
        BASE_WEIGTHS_PATH +
        'densenet121_weights_tf_dim_ordering_tf_kernels_notop.h5')
    DENSENET169_WEIGHT_PATH = (
        BASE_WEIGTHS_PATH +
        'densenet169_weights_tf_dim_ordering_tf_kernels.h5')
    DENSENET169_WEIGHT_PATH_NO_TOP = (
        BASE_WEIGTHS_PATH +
        'densenet169_weights_tf_dim_ordering_tf_kernels_notop.h5')
    DENSENET201_WEIGHT_PATH = (
        BASE_WEIGTHS_PATH +
        'densenet201_weights_tf_dim_ordering_tf_kernels.h5')
    DENSENET201_WEIGHT_PATH_NO_TOP = (
        BASE_WEIGTHS_PATH +
        'densenet201_weights_tf_dim_ordering_tf_kernels_notop.h5')
    
    
    def dense_block(x, blocks, name):
        """A dense block.
    
        # Arguments
            x: input tensor.
            blocks: integer, the number of building blocks.
            name: string, block label.
    
        # Returns
            output tensor for the block.
        """
        for i in range(blocks):
            x = conv_block(x, 32, name=name + '_block' + str(i + 1))
        return x
    
    
    def transition_block(x, reduction, name):
        """A transition block.
    
        # Arguments
            x: input tensor.
            reduction: float, compression rate at transition layers.
            name: string, block label.
    
        # Returns
            output tensor for the block.
        """
        bn_axis = 3 if backend.image_data_format() == 'channels_last' else 1
        x = layers.BatchNormalization(axis=bn_axis, epsilon=1.001e-5,
                                      name=name + '_bn')(x)
        x = layers.Activation('relu', name=name + '_relu')(x)
        x = layers.Conv2D(int(backend.int_shape(x)[bn_axis] * reduction), 1,
                          use_bias=False,
                          name=name + '_conv')(x)
        x = layers.AveragePooling2D(2, strides=2, name=name + '_pool')(x)
        return x
    
    
    def conv_block(x, growth_rate, name):
        """A building block for a dense block.
    
        # Arguments
            x: input tensor.
            growth_rate: float, growth rate at dense layers.
            name: string, block label.
    
        # Returns
            Output tensor for the block.
        """
        bn_axis = 3 if backend.image_data_format() == 'channels_last' else 1
        x1 = layers.BatchNormalization(axis=bn_axis,
                                       epsilon=1.001e-5,
                                       name=name + '_0_bn')(x)
        x1 = layers.Activation('relu', name=name + '_0_relu')(x1)
        x1 = layers.Conv2D(4 * growth_rate, 1,
                           use_bias=False,
                           name=name + '_1_conv')(x1)
        x1 = layers.BatchNormalization(axis=bn_axis, epsilon=1.001e-5,
                                       name=name + '_1_bn')(x1)
        x1 = layers.Activation('relu', name=name + '_1_relu')(x1)
        x1 = layers.Conv2D(growth_rate, 3,
                           padding='same',
                           use_bias=False,
                           name=name + '_2_conv')(x1)
        x = layers.Concatenate(axis=bn_axis, name=name + '_concat')([x, x1])
        return x
    
    
    def DenseNet(blocks,
                 include_top=True,
                 weights='imagenet',
                 input_tensor=None,
                 input_shape=None,
                 pooling=None,
                 classes=1000):
        """Instantiates the DenseNet architecture.
    
        Optionally loads weights pre-trained on ImageNet.
        Note that the data format convention used by the model is
        the one specified in your Keras config at `~/.keras/keras.json`.
    
        # Arguments
            blocks: numbers of building blocks for the four dense layers.
            include_top: whether to include the fully-connected
                layer at the top of the network.
            weights: one of `None` (random initialization),
                  'imagenet' (pre-training on ImageNet),
                  or the path to the weights file to be loaded.
            input_tensor: optional Keras tensor
                (i.e. output of `layers.Input()`)
                to use as image input for the model.
            input_shape: optional shape tuple, only to be specified
                if `include_top` is False (otherwise the input shape
                has to be `(224, 224, 3)` (with `channels_last` data format)
                or `(3, 224, 224)` (with `channels_first` data format).
                It should have exactly 3 inputs channels.
            pooling: optional pooling mode for feature extraction
                when `include_top` is `False`.
                - `None` means that the output of the model will be
                    the 4D tensor output of the
                    last convolutional layer.
                - `avg` means that global average pooling
                    will be applied to the output of the
                    last convolutional layer, and thus
                    the output of the model will be a 2D tensor.
                - `max` means that global max pooling will
                    be applied.
            classes: optional number of classes to classify images
                into, only to be specified if `include_top` is True, and
                if no `weights` argument is specified.
    
        # Returns
            A Keras model instance.
    
        # Raises
            ValueError: in case of invalid argument for `weights`,
                or invalid input shape.
        """
        if not (weights in {'imagenet', None} or os.path.exists(weights)):
            raise ValueError('The `weights` argument should be either '
                             '`None` (random initialization), `imagenet` '
                             '(pre-training on ImageNet), '
                             'or the path to the weights file to be loaded.')
    
        if weights == 'imagenet' and include_top and classes != 1000:
            raise ValueError('If using `weights` as imagenet with `include_top`'
                             ' as true, `classes` should be 1000')
    
        # Determine proper input shape
        input_shape = _obtain_input_shape(input_shape,
                                          default_size=224,
                                          min_size=221,
                                          data_format=backend.image_data_format(),
                                          require_flatten=include_top,
                                          weights=weights)
    
        if input_tensor is None:
            img_input = layers.Input(shape=input_shape)
        else:
            if not backend.is_keras_tensor(input_tensor):
                img_input = layers.Input(tensor=input_tensor, shape=input_shape)
            else:
                img_input = input_tensor
    
        bn_axis = 3 if backend.image_data_format() == 'channels_last' else 1
    
        x = layers.ZeroPadding2D(padding=((3, 3), (3, 3)))(img_input)
        x = layers.Conv2D(64, 7, strides=2, use_bias=False, name='conv1/conv')(x)
        x = layers.BatchNormalization(
            axis=bn_axis, epsilon=1.001e-5, name='conv1/bn')(x)
        x = layers.Activation('relu', name='conv1/relu')(x)
        x = layers.ZeroPadding2D(padding=((1, 1), (1, 1)))(x)
        x = layers.MaxPooling2D(3, strides=2, name='pool1')(x)
    
        x = dense_block(x, blocks[0], name='conv2')
        x = transition_block(x, 0.5, name='pool2')
        x = dense_block(x, blocks[1], name='conv3')
        x = transition_block(x, 0.5, name='pool3')
        x = dense_block(x, blocks[2], name='conv4')
        x = transition_block(x, 0.5, name='pool4')
        x = dense_block(x, blocks[3], name='conv5')
    
        x = layers.BatchNormalization(
            axis=bn_axis, epsilon=1.001e-5, name='bn')(x)
    
        if include_top:
            x = layers.GlobalAveragePooling2D(name='avg_pool')(x)
            x = layers.Dense(classes, activation='softmax', name='fc1000')(x)
        else:
            if pooling == 'avg':
                x = layers.GlobalAveragePooling2D(name='avg_pool')(x)
            elif pooling == 'max':
                x = layers.GlobalMaxPooling2D(name='max_pool')(x)
    
        # Ensure that the model takes into account
        # any potential predecessors of `input_tensor`.
        if input_tensor is not None:
            inputs = engine.get_source_inputs(input_tensor)
        else:
            inputs = img_input
    
        # Create model.
        if blocks == [6, 12, 24, 16]:
            model = models.Model(inputs, x, name='densenet121')
        elif blocks == [6, 12, 32, 32]:
            model = models.Model(inputs, x, name='densenet169')
        elif blocks == [6, 12, 48, 32]:
            model = models.Model(inputs, x, name='densenet201')
        else:
            model = models.Model(inputs, x, name='densenet')
    
        # Load weights.
        if weights == 'imagenet':
            if include_top:
                if blocks == [6, 12, 24, 16]:
                    weights_path = keras_utils.get_file(
                        'densenet121_weights_tf_dim_ordering_tf_kernels.h5',
                        DENSENET121_WEIGHT_PATH,
                        cache_subdir='models',
                        file_hash='0962ca643bae20f9b6771cb844dca3b0')
                elif blocks == [6, 12, 32, 32]:
                    weights_path = keras_utils.get_file(
                        'densenet169_weights_tf_dim_ordering_tf_kernels.h5',
                        DENSENET169_WEIGHT_PATH,
                        cache_subdir='models',
                        file_hash='bcf9965cf5064a5f9eb6d7dc69386f43')
                elif blocks == [6, 12, 48, 32]:
                    weights_path = keras_utils.get_file(
                        'densenet201_weights_tf_dim_ordering_tf_kernels.h5',
                        DENSENET201_WEIGHT_PATH,
                        cache_subdir='models',
                        file_hash='7bb75edd58cb43163be7e0005fbe95ef')
            else:
                if blocks == [6, 12, 24, 16]:
                    weights_path = keras_utils.get_file(
                        'densenet121_weights_tf_dim_ordering_tf_kernels_notop.h5',
                        DENSENET121_WEIGHT_PATH_NO_TOP,
                        cache_subdir='models',
                        file_hash='4912a53fbd2a69346e7f2c0b5ec8c6d3')
                elif blocks == [6, 12, 32, 32]:
                    weights_path = keras_utils.get_file(
                        'densenet169_weights_tf_dim_ordering_tf_kernels_notop.h5',
                        DENSENET169_WEIGHT_PATH_NO_TOP,
                        cache_subdir='models',
                        file_hash='50662582284e4cf834ce40ab4dfa58c6')
                elif blocks == [6, 12, 48, 32]:
                    weights_path = keras_utils.get_file(
                        'densenet201_weights_tf_dim_ordering_tf_kernels_notop.h5',
                        DENSENET201_WEIGHT_PATH_NO_TOP,
                        cache_subdir='models',
                        file_hash='1c2de60ee40562448dbac34a0737e798')
            model.load_weights(weights_path)
        elif weights is not None:
            model.load_weights(weights)
    
        return model
    
    
    def DenseNet121(include_top=True,
                    weights='imagenet',
                    input_tensor=None,
                    input_shape=None,
                    pooling=None,
                    classes=1000):
        return DenseNet([6, 12, 24, 16],
                        include_top, weights,
                        input_tensor, input_shape,
                        pooling, classes)
    
    
    def DenseNet169(include_top=True,
                    weights='imagenet',
                    input_tensor=None,
                    input_shape=None,
                    pooling=None,
                    classes=1000):
        return DenseNet([6, 12, 32, 32],
                        include_top, weights,
                        input_tensor, input_shape,
                        pooling, classes)
    
    
    def DenseNet201(include_top=True,
                    weights='imagenet',
                    input_tensor=None,
                    input_shape=None,
                    pooling=None,
                    classes=1000):
        return DenseNet([6, 12, 48, 32],
                        include_top, weights,
                        input_tensor, input_shape,
                        pooling, classes)
    
    
    def preprocess_input(x, data_format=None):
        """Preprocesses a numpy array encoding a batch of images.
    
        # Arguments
            x: a 3D or 4D numpy array consists of RGB values within [0, 255].
            data_format: data format of the image tensor.
    
        # Returns
            Preprocessed array.
        """
        return imagenet_utils.preprocess_input(x, data_format, mode='torch')
    
    
    setattr(DenseNet121, '__doc__', DenseNet.__doc__)
    setattr(DenseNet169, '__doc__', DenseNet.__doc__)
    setattr(DenseNet201, '__doc__', DenseNet.__doc__)

    从keras导入densenet模型需要以下代码

    from keras.applications.densenet import DenseNet201,preprocess_input
    
    #base_model = DenseNet(weights='imagenet', include_top=False)
    base_model = DenseNet201(weights=None, include_top=False)
    
    x = base_model.output
    x = GlobalAveragePooling2D()(x) 
    x = Dense(1024, activation='relu')(x)
    predictions = Dense(6941, activation='sigmoid')(x)
    model = Model(inputs=base_model.input, outputs=predictions)
    
    model.summary()
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  • 原文地址:https://www.cnblogs.com/feifanrensheng/p/9677925.html
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