Add Xception network

fchollet · fchollet · commit 5f77a4dbe7bd · 2016-10-19T13:34:23.000-07:00
diff --git a/xception.py b/xception.py
@@ -0,0 +1,226 @@
+# -*- coding: utf-8 -*-
+'''Xception V1 model for Keras.
+
+On ImageNet, this model gets to a top-1 validation accuracy of 0.790.
+and a top-5 validation accuracy of 0.945.
+
+Do note that the input image format for this model is different than for
+the VGG16 and ResNet models (299x299 instead of 224x224),
+and that the input preprocessing function
+is also different (same as Inception V3).
+
+Also do note that this model is only available for the TensorFlow backend,
+due to its reliance on `SeparableConvolution` layers.
+
+# Reference:
+
+- [Xception: Deep Learning with Depthwise Separable Convolutions](https://arxiv.org/abs/1610.02357)
+
+'''
+from __future__ import print_function
+from __future__ import absolute_import
+
+import warnings
+import numpy as np
+
+from keras.models import Model
+from keras.layers import Dense, Input, BatchNormalization, Activation, merge
+from keras.layers import Conv2D, SeparableConv2D, MaxPooling2D, GlobalAveragePooling2D
+from keras.preprocessing import image
+from keras.utils.data_utils import get_file
+from keras import backend as K
+from imagenet_utils import decode_predictions
+
+
+TF_WEIGHTS_PATH = 'https://github.com/fchollet/deep-learning-models/releases/download/v0.4/xception_weights_tf_dim_ordering_tf_kernels.h5'
+TF_WEIGHTS_PATH_NO_TOP = 'https://github.com/fchollet/deep-learning-models/releases/download/v0.4/xception_weights_tf_dim_ordering_tf_kernels_notop.h5'
+
+
+def Xception(include_top=True, weights='imagenet',
+             input_tensor=None):
+    '''Instantiate the Xception architecture,
+    optionally loading weights pre-trained
+    on ImageNet. This model is available for TensorFlow only,
+    and can only be used with inputs following the TensorFlow
+    dimension ordering `(width, height, channels)`.
+    You should set `image_dim_ordering="tf"` in your Keras config
+    located at ~/.keras/keras.json.
+
+    Note that the default input image size for this model is 299x299.
+
+    # Arguments
+        include_top: whether to include the fully-connected
+            layer at the top of the network.
+        weights: one of `None` (random initialization)
+            or "imagenet" (pre-training on ImageNet).
+        input_tensor: optional Keras tensor (i.e. output of `layers.Input()`)
+            to use as image input for the model.
+
+    # Returns
+        A Keras model instance.
+    '''
+    if weights not in {'imagenet', None}:
+        raise ValueError('The `weights` argument should be either '
+                         '`None` (random initialization) or `imagenet` '
+                         '(pre-training on ImageNet).')
+    if K.backend() != 'tensorflow':
+        raise Exception('The Xception model is only available with '
+                        'the TensorFlow backend.')
+    if K.image_dim_ordering() != 'tf':
+        warnings.warn('The Xception model is only available for the '
+                      'input dimension ordering "tf" '
+                      '(width, height, channels). '
+                      'However your settings specify the default '
+                      'dimension ordering "th" (channels, width, height). '
+                      'You should set `image_dim_ordering="tf"` in your Keras '
+                      'config located at ~/.keras/keras.json. '
+                      'The model being returned right now will expect inputs '
+                      'to follow the "tf" dimension ordering.')
+        K.set_image_dim_ordering('tf')
+        old_dim_ordering = 'th'
+    else:
+        old_dim_ordering = None
+
+    # Determine proper input shape
+    if include_top:
+        input_shape = (299, 299, 3)
+    else:
+        input_shape = (None, None, 3)
+
+    if input_tensor is None:
+        img_input = Input(shape=input_shape)
+    else:
+        if not K.is_keras_tensor(input_tensor):
+            img_input = Input(tensor=input_tensor, shape=input_shape)
+        else:
+            img_input = input_tensor
+
+    x = Conv2D(32, 3, 3, subsample=(2, 2), bias=False, name='block1_conv1')(img_input)
+    x = BatchNormalization(name='block1_conv1_bn')(x)
+    x = Activation('relu', name='block1_conv1_act')(x)
+    x = Conv2D(64, 3, 3, bias=False, name='block1_conv2')(x)
+    x = BatchNormalization(name='block1_conv2_bn')(x)
+    x = Activation('relu', name='block1_conv2_act')(x)
+
+    residual = Conv2D(128, 1, 1, subsample=(2, 2),
+                      border_mode='same', bias=False)(x)
+    residual = BatchNormalization()(residual)
+
+    x = SeparableConv2D(128, 3, 3, border_mode='same', bias=False, name='block2_sepconv1')(x)
+    x = BatchNormalization(name='block2_sepconv1_bn')(x)
+    x = Activation('relu', name='block2_sepconv2_act')(x)
+    x = SeparableConv2D(128, 3, 3, border_mode='same', bias=False, name='block2_sepconv2')(x)
+    x = BatchNormalization(name='block2_sepconv2_bn')(x)
+
+    x = MaxPooling2D((3, 3), strides=(2, 2), border_mode='same', name='block2_pool')(x)
+    x = merge([x, residual], mode='sum')
+
+    residual = Conv2D(256, 1, 1, subsample=(2, 2),
+                      border_mode='same', bias=False)(x)
+    residual = BatchNormalization()(residual)
+
+    x = Activation('relu', name='block3_sepconv1_act')(x)
+    x = SeparableConv2D(256, 3, 3, border_mode='same', bias=False, name='block3_sepconv1')(x)
+    x = BatchNormalization(name='block3_sepconv1_bn')(x)
+    x = Activation('relu', name='block3_sepconv2_act')(x)
+    x = SeparableConv2D(256, 3, 3, border_mode='same', bias=False, name='block3_sepconv2')(x)
+    x = BatchNormalization(name='block3_sepconv2_bn')(x)
+
+    x = MaxPooling2D((3, 3), strides=(2, 2), border_mode='same', name='block3_pool')(x)
+    x = merge([x, residual], mode='sum')
+
+    residual = Conv2D(728, 1, 1, subsample=(2, 2),
+                      border_mode='same', bias=False)(x)
+    residual = BatchNormalization()(residual)
+
+    x = Activation('relu', name='block4_sepconv1_act')(x)
+    x = SeparableConv2D(728, 3, 3, border_mode='same', bias=False, name='block4_sepconv1')(x)
+    x = BatchNormalization(name='block4_sepconv1_bn')(x)
+    x = Activation('relu', name='block4_sepconv2_act')(x)
+    x = SeparableConv2D(728, 3, 3, border_mode='same', bias=False, name='block4_sepconv2')(x)
+    x = BatchNormalization(name='block4_sepconv2_bn')(x)
+
+    x = MaxPooling2D((3, 3), strides=(2, 2), border_mode='same', name='block4_pool')(x)
+    x = merge([x, residual], mode='sum')
+
+    for i in range(8):
+        residual = x
+        prefix = 'block' + str(i + 5)
+
+        x = Activation('relu', name=prefix + '_sepconv1_act')(x)
+        x = SeparableConv2D(728, 3, 3, border_mode='same', bias=False, name=prefix + '_sepconv1')(x)
+        x = BatchNormalization(name=prefix + '_sepconv1_bn')(x)
+        x = Activation('relu', name=prefix + '_sepconv2_act')(x)
+        x = SeparableConv2D(728, 3, 3, border_mode='same', bias=False, name=prefix + '_sepconv2')(x)
+        x = BatchNormalization(name=prefix + '_sepconv2_bn')(x)
+        x = Activation('relu', name=prefix + '_sepconv3_act')(x)
+        x = SeparableConv2D(728, 3, 3, border_mode='same', bias=False, name=prefix + '_sepconv3')(x)
+        x = BatchNormalization(name=prefix + '_sepconv3_bn')(x)
+
+        x = merge([x, residual], mode='sum')
+
+    residual = Conv2D(1024, 1, 1, subsample=(2, 2),
+                      border_mode='same', bias=False)(x)
+    residual = BatchNormalization()(residual)
+
+    x = Activation('relu', name='block13_sepconv1_act')(x)
+    x = SeparableConv2D(728, 3, 3, border_mode='same', bias=False, name='block13_sepconv1')(x)
+    x = BatchNormalization(name='block13_sepconv1_bn')(x)
+    x = Activation('relu', name='block13_sepconv2_act')(x)
+    x = SeparableConv2D(1024, 3, 3, border_mode='same', bias=False, name='block13_sepconv2')(x)
+    x = BatchNormalization(name='block13_sepconv2_bn')(x)
+
+    x = MaxPooling2D((3, 3), strides=(2, 2), border_mode='same', name='block13_pool')(x)
+    x = merge([x, residual], mode='sum')
+
+    x = SeparableConv2D(1536, 3, 3, border_mode='same', bias=False, name='block14_sepconv1')(x)
+    x = BatchNormalization(name='block14_sepconv1_bn')(x)
+    x = Activation('relu', name='block14_sepconv1_act')(x)
+
+    x = SeparableConv2D(2048, 3, 3, border_mode='same', bias=False, name='block14_sepconv2')(x)
+    x = BatchNormalization(name='block14_sepconv2_bn')(x)
+    x = Activation('relu', name='block14_sepconv2_act')(x)
+
+    if include_top:
+        x = GlobalAveragePooling2D(name='avg_pool')(x)
+        x = Dense(1000, activation='softmax', name='predictions')(x)
+
+    # Create model
+    model = Model(img_input, x)
+
+    # load weights
+    if weights == 'imagenet':
+        if include_top:
+            weights_path = get_file('xception_weights_tf_dim_ordering_tf_kernels.h5',
+                                    TF_WEIGHTS_PATH,
+                                    cache_subdir='models')
+        else:
+            weights_path = get_file('xception_weights_tf_dim_ordering_tf_kernels_notop.h5',
+                                    TF_WEIGHTS_PATH_NO_TOP,
+                                    cache_subdir='models')
+        model.load_weights(weights_path)
+
+    if old_dim_ordering:
+        K.set_image_dim_ordering(old_dim_ordering)
+    return model
+
+
+def preprocess_input(x):
+    x /= 255.
+    x -= 0.5
+    x *= 2.
+    return x
+
+
+if __name__ == '__main__':
+    model = Xception(include_top=True, weights='imagenet')
+
+    img_path = 'elephant.jpg'
+    img = image.load_img(img_path, target_size=(299, 299))
+    x = image.img_to_array(img)
+    x = np.expand_dims(x, axis=0)
+    x = preprocess_input(x)
+    print('Input image shape:', x.shape)
+
+    preds = model.predict(x)
+    print('Predicted:', decode_predictions(preds, 1))
