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mobilenet.py
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mobilenet.py
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#!/usr/bin/env python3
# -*- coding: utf-8 -*-
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
import tensorflow as tf
import tensorflow.contrib.slim as slim
def mobilenet(inputs,
num_classes=1000,
is_training=True,
width_multiplier=1,
scope='MobileNet'):
""" MobileNet
More detail, please refer to Google's paper(https://arxiv.org/abs/1704.04861).
Args:
inputs: a tensor of size [batch_size, height, width, channels].
num_classes: number of predicted classes.
is_training: whether or not the model is being trained.
scope: Optional scope for the variables.
Returns:
logits: the pre-softmax activations, a tensor of size
[batch_size, `num_classes`]
end_points: a dictionary from components of the network to the corresponding
activation.
"""
def _depthwise_separable_conv(inputs,
num_pwc_filters,
width_multiplier,
sc,
downsample=False):
""" Helper function to build the depth-wise separable convolution layer.
"""
num_pwc_filters = round(num_pwc_filters * width_multiplier)
_stride = 2 if downsample else 1
# skip pointwise by setting num_outputs=None
depthwise_conv = slim.separable_convolution2d(inputs,
num_outputs=None,
stride=_stride,
depth_multiplier=1,
kernel_size=[3, 3],
scope=sc+'/depthwise_conv')
bn = slim.batch_norm(depthwise_conv, scope=sc+'/dw_batch_norm')
pointwise_conv = slim.convolution2d(bn,
num_pwc_filters,
kernel_size=[1, 1],
scope=sc+'/pointwise_conv')
bn = slim.batch_norm(pointwise_conv, scope=sc+'/pw_batch_norm')
return bn
with tf.variable_scope(scope) as sc:
end_points_collection = sc.name + '_end_points'
with slim.arg_scope([slim.convolution2d, slim.separable_convolution2d],
activation_fn=None,
outputs_collections=[end_points_collection]):
with slim.arg_scope([slim.batch_norm],
is_training=is_training,
activation_fn=tf.nn.relu,
fused=True):
net = slim.convolution2d(inputs, round(32 * width_multiplier), [3, 3], stride=2, padding='SAME', scope='conv_1')
net = slim.batch_norm(net, scope='conv_1/batch_norm')
net = _depthwise_separable_conv(net, 64, width_multiplier, sc='conv_ds_2')
net = _depthwise_separable_conv(net, 128, width_multiplier, downsample=True, sc='conv_ds_3')
net = _depthwise_separable_conv(net, 128, width_multiplier, sc='conv_ds_4')
net = _depthwise_separable_conv(net, 256, width_multiplier, downsample=True, sc='conv_ds_5')
net = _depthwise_separable_conv(net, 256, width_multiplier, sc='conv_ds_6')
net = _depthwise_separable_conv(net, 512, width_multiplier, downsample=True, sc='conv_ds_7')
net = _depthwise_separable_conv(net, 512, width_multiplier, sc='conv_ds_8')
net = _depthwise_separable_conv(net, 512, width_multiplier, sc='conv_ds_9')
net = _depthwise_separable_conv(net, 512, width_multiplier, sc='conv_ds_10')
net = _depthwise_separable_conv(net, 512, width_multiplier, sc='conv_ds_11')
net = _depthwise_separable_conv(net, 512, width_multiplier, sc='conv_ds_12')
net = _depthwise_separable_conv(net, 1024, width_multiplier, downsample=True, sc='conv_ds_13')
net = _depthwise_separable_conv(net, 1024, width_multiplier, sc='conv_ds_14')
net = slim.avg_pool2d(net, [7, 7], scope='avg_pool_15')
end_points = slim.utils.convert_collection_to_dict(end_points_collection)
net = tf.squeeze(net, [1, 2], name='SpatialSqueeze')
end_points['squeeze'] = net
logits = slim.fully_connected(net, num_classes, activation_fn=None, scope='fc_16')
predictions = slim.softmax(logits, scope='Predictions')
end_points['Logits'] = logits
end_points['Predictions'] = predictions
return logits, end_points
mobilenet.default_image_size = 224
def mobilenet_arg_scope(weight_decay=0.0):
"""Defines the default mobilenet argument scope.
Args:
weight_decay: The weight decay to use for regularizing the model.
Returns:
An `arg_scope` to use for the MobileNet model.
"""
with slim.arg_scope(
[slim.convolution2d, slim.separable_convolution2d],
weights_initializer=slim.initializers.xavier_initializer(),
biases_initializer=slim.init_ops.zeros_initializer(),
weights_regularizer=slim.l2_regularizer(weight_decay)) as sc:
return sc