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deeplab_v3_plus.py
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deeplab_v3_plus.py
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# -*- coding: utf-8 -*-
""" Deeplabv3+ model for Keras.
This file is based on this repo by Emil Zakirov and others:
https://github.com/bonlime/keras-deeplab-v3-plus
This model is based on TF repo:
https://github.com/tensorflow/models/tree/master/research/deeplab
On Pascal VOC, original model gets to 84.56% mIOU
MobileNetv2 backbone is based on this repo:
https://github.com/JonathanCMitchell/mobilenet_v2_keras
# Reference
- [Encoder-Decoder with Atrous Separable Convolution
for Semantic Image Segmentation](https://arxiv.org/pdf/1802.02611.pdf)
- [Xception: Deep Learning with Depthwise Separable Convolutions]
(https://arxiv.org/abs/1610.02357)
- [Inverted Residuals and Linear Bottlenecks: Mobile Networks for
Classification, Detection and Segmentation](https://arxiv.org/abs/1801.04381)
"""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
import tensorflow as tf
from tensorflow.keras.models import Model
from tensorflow.keras import layers
from tensorflow.keras.layers import Input
from tensorflow.keras.layers import Reshape
from tensorflow.keras.layers import Activation
from tensorflow.keras.layers import Concatenate
from tensorflow.keras.layers import Add
from tensorflow.keras.layers import Dropout
from tensorflow.keras.layers import BatchNormalization
from tensorflow.keras.layers import Conv2D
from tensorflow.keras.layers import DepthwiseConv2D
from tensorflow.keras.layers import ZeroPadding2D
from tensorflow.keras.layers import GlobalAveragePooling2D
from tensorflow.keras.utils import *
from tensorflow.keras import backend as K
from tensorflow.keras.applications.imagenet_utils import preprocess_input
from tensorflow.keras.utils import get_source_inputs
WEIGHTS_PATH_X = "https://github.com/bonlime/keras-deeplab-v3-plus/releases/download/1.1/deeplabv3_xception_tf_dim_ordering_tf_kernels.h5"
WEIGHTS_PATH_MOBILE = "https://github.com/bonlime/keras-deeplab-v3-plus/releases/download/1.1/deeplabv3_mobilenetv2_tf_dim_ordering_tf_kernels.h5"
WEIGHTS_PATH_X_CS = "https://github.com/bonlime/keras-deeplab-v3-plus/releases/download/1.2/deeplabv3_xception_tf_dim_ordering_tf_kernels_cityscapes.h5"
WEIGHTS_PATH_MOBILE_CS = "https://github.com/bonlime/keras-deeplab-v3-plus/releases/download/1.2/deeplabv3_mobilenetv2_tf_dim_ordering_tf_kernels_cityscapes.h5"
def SepConv_BN(x, filters, prefix, stride=1, kernel_size=3, rate=1, depth_activation=False, epsilon=1e-3):
""" SepConv with BN between depthwise & pointwise. Optionally add activation after BN
Implements right "same" padding for even kernel sizes
Args:
x: input tensor
filters: num of filters in pointwise convolution
prefix: prefix before name
stride: stride at depthwise conv
kernel_size: kernel size for depthwise convolution
rate: atrous rate for depthwise convolution
depth_activation: flag to use activation between depthwise & poinwise convs
epsilon: epsilon to use in BN layer
"""
if stride == 1:
depth_padding = 'same'
else:
kernel_size_effective = kernel_size + (kernel_size - 1) * (rate - 1)
pad_total = kernel_size_effective - 1
pad_beg = pad_total // 2
pad_end = pad_total - pad_beg
x = ZeroPadding2D((pad_beg, pad_end))(x)
depth_padding = 'valid'
if not depth_activation:
x = Activation(tf.nn.relu)(x)
x = DepthwiseConv2D((kernel_size, kernel_size), strides=(stride, stride), dilation_rate=(rate, rate),
padding=depth_padding, use_bias=False, name=prefix + '_depthwise')(x)
x = BatchNormalization(name=prefix + '_depthwise_BN', epsilon=epsilon)(x)
if depth_activation:
x = Activation(tf.nn.relu)(x)
x = Conv2D(filters, (1, 1), padding='same',
use_bias=False, name=prefix + '_pointwise')(x)
x = BatchNormalization(name=prefix + '_pointwise_BN', epsilon=epsilon)(x)
if depth_activation:
x = Activation(tf.nn.relu)(x)
return x
def _conv2d_same(x, filters, prefix, stride=1, kernel_size=3, rate=1):
"""Implements right 'same' padding for even kernel sizes
Without this there is a 1 pixel drift when stride = 2
Args:
x: input tensor
filters: num of filters in pointwise convolution
prefix: prefix before name
stride: stride at depthwise conv
kernel_size: kernel size for depthwise convolution
rate: atrous rate for depthwise convolution
"""
if stride == 1:
return Conv2D(filters,
(kernel_size, kernel_size),
strides=(stride, stride),
padding='same', use_bias=False,
dilation_rate=(rate, rate),
name=prefix)(x)
else:
kernel_size_effective = kernel_size + (kernel_size - 1) * (rate - 1)
pad_total = kernel_size_effective - 1
pad_beg = pad_total // 2
pad_end = pad_total - pad_beg
x = ZeroPadding2D((pad_beg, pad_end))(x)
return Conv2D(filters,
(kernel_size, kernel_size),
strides=(stride, stride),
padding='valid', use_bias=False,
dilation_rate=(rate, rate),
name=prefix)(x)
def _xception_block(inputs, depth_list, prefix, skip_connection_type, stride,
rate=1, depth_activation=False, return_skip=False):
""" Basic building block of modified Xception network
Args:
inputs: input tensor
depth_list: number of filters in each SepConv layer. len(depth_list) == 3
prefix: prefix before name
skip_connection_type: one of {'conv','sum','none'}
stride: stride at last depthwise conv
rate: atrous rate for depthwise convolution
depth_activation: flag to use activation between depthwise & pointwise convs
return_skip: flag to return additional tensor after 2 SepConvs for decoder
"""
residual = inputs
for i in range(3):
residual = SepConv_BN(residual,
depth_list[i],
prefix + '_separable_conv{}'.format(i + 1),
stride=stride if i == 2 else 1,
rate=rate,
depth_activation=depth_activation)
if i == 1:
skip = residual
if skip_connection_type == 'conv':
shortcut = _conv2d_same(inputs, depth_list[-1], prefix + '_shortcut',
kernel_size=1,
stride=stride)
shortcut = BatchNormalization(name=prefix + '_shortcut_BN')(shortcut)
outputs = layers.add([residual, shortcut])
elif skip_connection_type == 'sum':
outputs = layers.add([residual, inputs])
elif skip_connection_type == 'none':
outputs = residual
if return_skip:
return outputs, skip
else:
return outputs
def _make_divisible(v, divisor, min_value=None):
if min_value is None:
min_value = divisor
new_v = max(min_value, int(v + divisor / 2) // divisor * divisor)
# Make sure that round down does not go down by more than 10%.
if new_v < 0.9 * v:
new_v += divisor
return new_v
def _inverted_res_block(inputs, expansion, stride, alpha, filters, block_id, skip_connection, rate=1):
in_channels = inputs.shape[-1] # inputs._keras_shape[-1]
pointwise_conv_filters = int(filters * alpha)
pointwise_filters = _make_divisible(pointwise_conv_filters, 8)
x = inputs
prefix = 'expanded_conv_{}_'.format(block_id)
if block_id:
# Expand
x = Conv2D(expansion * in_channels, kernel_size=1, padding='same',
use_bias=False, activation=None,
name=prefix + 'expand')(x)
x = BatchNormalization(epsilon=1e-3, momentum=0.999,
name=prefix + 'expand_BN')(x)
x = Activation(tf.nn.relu6, name=prefix + 'expand_relu')(x)
else:
prefix = 'expanded_conv_'
# Depthwise
x = DepthwiseConv2D(kernel_size=3, strides=stride, activation=None,
use_bias=False, padding='same', dilation_rate=(rate, rate),
name=prefix + 'depthwise')(x)
x = BatchNormalization(epsilon=1e-3, momentum=0.999,
name=prefix + 'depthwise_BN')(x)
x = Activation(tf.nn.relu6, name=prefix + 'depthwise_relu')(x)
# Project
x = Conv2D(pointwise_filters,
kernel_size=1, padding='same', use_bias=False, activation=None,
name=prefix + 'project')(x)
x = BatchNormalization(epsilon=1e-3, momentum=0.999,
name=prefix + 'project_BN')(x)
if skip_connection:
return Add(name=prefix + 'add')([inputs, x])
# if in_channels == pointwise_filters and stride == 1:
# return Add(name='res_connect_' + str(block_id))([inputs, x])
return x
def create_model_deeplabv3plus(weights='pascal_voc',
input_tensor=None,
input_shape=(512, 512, 3),
classes=21,
backbone='xception',
OS=16,
alpha=1.,
activation=None,
transfer_learning=None):
""" Instantiates the Deeplabv3+ architecture
Optionally loads weights pre-trained
on PASCAL VOC or Cityscapes. This model is available for TensorFlow only.
# Arguments
weights: one of 'pascal_voc' (pre-trained on pascal voc),
'cityscapes' (pre-trained on cityscape) or None (random initialization)
input_tensor: optional Keras tensor (i.e. output of `layers.Input()`)
to use as image input for the model.
input_shape: shape of input image. format HxWxC
PASCAL VOC model was trained on (512,512,3) images. None is allowed as shape/width
classes: number of desired classes. PASCAL VOC has 21 classes, Cityscapes has 19 classes.
If number of classes not aligned with the weights used, last layer is initialized randomly
backbone: backbone to use. one of {'xception','mobilenetv2'}
activation: optional activation to add to the top of the network.
One of 'softmax', 'sigmoid' or None
OS: determines input_shape/feature_extractor_output ratio. One of {8,16}.
Used only for xception backbone.
alpha: controls the width of the MobileNetV2 network. This is known as the
width multiplier in the MobileNetV2 paper.
- If `alpha` < 1.0, proportionally decreases the number
of filters in each layer.
- If `alpha` > 1.0, proportionally increases the number
of filters in each layer.
- If `alpha` = 1, default number of filters from the paper
are used at each layer.
Used only for mobilenetv2 backbone. Pretrained is only available for alpha=1.
# Returns
A Keras model instance.
# Raises
RuntimeError: If attempting to run this model with a
backend that does not support separable convolutions.
ValueError: in case of invalid argument for `weights` or `backbone`
"""
if not (weights in {'pascal_voc', 'cityscapes', None}):
raise ValueError('The `weights` argument should be either '
'`None` (random initialization), `pascal_voc`, or `cityscapes` '
'(pre-trained on PASCAL VOC)')
if not (backbone in {'xception', 'mobilenetv2'}):
raise ValueError('The `backbone` argument should be either '
'`xception` or `mobilenetv2` ')
if input_tensor is None:
img_input = Input(shape=input_shape)
else:
img_input = input_tensor
if backbone == 'xception':
if OS == 8:
entry_block3_stride = 1
middle_block_rate = 2 # ! Not mentioned in paper, but required
exit_block_rates = (2, 4)
atrous_rates = (12, 24, 36)
else:
entry_block3_stride = 2
middle_block_rate = 1
exit_block_rates = (1, 2)
atrous_rates = (6, 12, 18)
x = Conv2D(32, (3, 3), strides=(2, 2),
name='entry_flow_conv1_1', use_bias=False, padding='same')(img_input)
x = BatchNormalization(name='entry_flow_conv1_1_BN')(x)
x = Activation(tf.nn.relu)(x)
x = _conv2d_same(x, 64, 'entry_flow_conv1_2', kernel_size=3, stride=1)
x = BatchNormalization(name='entry_flow_conv1_2_BN')(x)
x = Activation(tf.nn.relu)(x)
x = _xception_block(x, [128, 128, 128], 'entry_flow_block1',
skip_connection_type='conv', stride=2,
depth_activation=False)
x, skip1 = _xception_block(x, [256, 256, 256], 'entry_flow_block2',
skip_connection_type='conv', stride=2,
depth_activation=False, return_skip=True)
x = _xception_block(x, [728, 728, 728], 'entry_flow_block3',
skip_connection_type='conv', stride=entry_block3_stride,
depth_activation=False)
for i in range(16):
x = _xception_block(x, [728, 728, 728], 'middle_flow_unit_{}'.format(i + 1),
skip_connection_type='sum', stride=1, rate=middle_block_rate,
depth_activation=False)
x = _xception_block(x, [728, 1024, 1024], 'exit_flow_block1',
skip_connection_type='conv', stride=1, rate=exit_block_rates[0],
depth_activation=False)
x = _xception_block(x, [1536, 1536, 2048], 'exit_flow_block2',
skip_connection_type='none', stride=1, rate=exit_block_rates[1],
depth_activation=True)
else:
OS = 8
first_block_filters = _make_divisible(32 * alpha, 8)
x = Conv2D(first_block_filters,
kernel_size=3,
strides=(2, 2), padding='same', use_bias=False,
name='Conv' if input_shape[2] == 3 else 'Conv_')(img_input)
x = BatchNormalization(
epsilon=1e-3, momentum=0.999, name='Conv_BN')(x)
x = Activation(tf.nn.relu6, name='Conv_Relu6')(x)
x = _inverted_res_block(x, filters=16, alpha=alpha, stride=1,
expansion=1, block_id=0, skip_connection=False)
x = _inverted_res_block(x, filters=24, alpha=alpha, stride=2,
expansion=6, block_id=1, skip_connection=False)
x = _inverted_res_block(x, filters=24, alpha=alpha, stride=1,
expansion=6, block_id=2, skip_connection=True)
x = _inverted_res_block(x, filters=32, alpha=alpha, stride=2,
expansion=6, block_id=3, skip_connection=False)
x = _inverted_res_block(x, filters=32, alpha=alpha, stride=1,
expansion=6, block_id=4, skip_connection=True)
x = _inverted_res_block(x, filters=32, alpha=alpha, stride=1,
expansion=6, block_id=5, skip_connection=True)
# stride in block 6 changed from 2 -> 1, so we need to use rate = 2
x = _inverted_res_block(x, filters=64, alpha=alpha, stride=1, # 1!
expansion=6, block_id=6, skip_connection=False)
x = _inverted_res_block(x, filters=64, alpha=alpha, stride=1, rate=2,
expansion=6, block_id=7, skip_connection=True)
x = _inverted_res_block(x, filters=64, alpha=alpha, stride=1, rate=2,
expansion=6, block_id=8, skip_connection=True)
x = _inverted_res_block(x, filters=64, alpha=alpha, stride=1, rate=2,
expansion=6, block_id=9, skip_connection=True)
x = _inverted_res_block(x, filters=96, alpha=alpha, stride=1, rate=2,
expansion=6, block_id=10, skip_connection=False)
x = _inverted_res_block(x, filters=96, alpha=alpha, stride=1, rate=2,
expansion=6, block_id=11, skip_connection=True)
x = _inverted_res_block(x, filters=96, alpha=alpha, stride=1, rate=2,
expansion=6, block_id=12, skip_connection=True)
x = _inverted_res_block(x, filters=160, alpha=alpha, stride=1, rate=2, # 1!
expansion=6, block_id=13, skip_connection=False)
x = _inverted_res_block(x, filters=160, alpha=alpha, stride=1, rate=4,
expansion=6, block_id=14, skip_connection=True)
x = _inverted_res_block(x, filters=160, alpha=alpha, stride=1, rate=4,
expansion=6, block_id=15, skip_connection=True)
x = _inverted_res_block(x, filters=320, alpha=alpha, stride=1, rate=4,
expansion=6, block_id=16, skip_connection=False)
# end of feature extractor
# branching for Atrous Spatial Pyramid Pooling
# Image Feature branch
shape_before = tf.shape(x)
b4 = GlobalAveragePooling2D()(x)
b4_shape = tf.keras.backend.int_shape(b4)
# from (b_size, channels)->(b_size, 1, 1, channels)
b4 = Reshape((1, 1, b4_shape[1]))(b4)
b4 = Conv2D(256, (1, 1), padding='same',
use_bias=False, name='image_pooling')(b4)
b4 = BatchNormalization(name='image_pooling_BN', epsilon=1e-5)(b4)
b4 = Activation(tf.nn.relu)(b4)
# upsample. have to use compat because of the option align_corners
size_before = tf.keras.backend.int_shape(x)
## gians replace tf.keras.layers.experimental.preprocessing.Resizing
## with tf.image.resize because Tf library compatibility
# b4 = tf.keras.layers.experimental.preprocessing.Resizing(
# *size_before[1:3], interpolation="bilinear"
# )(b4)
size_tmp = (size_before[1], size_before[2])
b4 = tf.image.resize(b4, size_tmp)
# simple 1x1
b0 = Conv2D(256, (1, 1), padding='same', use_bias=False, name='aspp0')(x)
b0 = BatchNormalization(name='aspp0_BN', epsilon=1e-5)(b0)
b0 = Activation(tf.nn.relu, name='aspp0_activation')(b0)
# there are only 2 branches in mobilenetV2. not sure why
if backbone == 'xception':
# rate = 6 (12)
b1 = SepConv_BN(x, 256, 'aspp1',
rate=atrous_rates[0], depth_activation=True, epsilon=1e-5)
# rate = 12 (24)
b2 = SepConv_BN(x, 256, 'aspp2',
rate=atrous_rates[1], depth_activation=True, epsilon=1e-5)
# rate = 18 (36)
b3 = SepConv_BN(x, 256, 'aspp3',
rate=atrous_rates[2], depth_activation=True, epsilon=1e-5)
# concatenate ASPP branches & project
x = Concatenate()([b4, b0, b1, b2, b3])
else:
x = Concatenate()([b4, b0])
x = Conv2D(256, (1, 1), padding='same',
use_bias=False, name='concat_projection')(x)
x = BatchNormalization(name='concat_projection_BN', epsilon=1e-5)(x)
x = Activation(tf.nn.relu)(x)
x = Dropout(0.1)(x)
# DeepLab v.3+ decoder
if backbone == 'xception':
# Feature projection
# x4 (x2) block
skip_size = tf.keras.backend.int_shape(skip1)
# x = tf.keras.layers.experimental.preprocessing.Resizing(
# *skip_size[1:3], interpolation="bilinear"
# )(x)
size_tmp = (skip_size[1], skip_size[2])
x = tf.image.resize(x, size_tmp)
dec_skip1 = Conv2D(48, (1, 1), padding='same',
use_bias=False, name='feature_projection0')(skip1)
dec_skip1 = BatchNormalization(
name='feature_projection0_BN', epsilon=1e-5)(dec_skip1)
dec_skip1 = Activation(tf.nn.relu)(dec_skip1)
x = Concatenate()([x, dec_skip1])
x = SepConv_BN(x, 256, 'decoder_conv0',
depth_activation=True, epsilon=1e-5)
x = SepConv_BN(x, 256, 'decoder_conv1',
depth_activation=True, epsilon=1e-5)
# you can use it with arbitary number of classes
if (weights == 'pascal_voc' and classes == 21) or (weights == 'cityscapes' and classes == 19):
last_layer_name = 'logits_semantic'
else:
last_layer_name = 'custom_logits_semantic'
x = Conv2D(classes, (1, 1), padding='same', name=last_layer_name)(x)
size_before3 = tf.keras.backend.int_shape(img_input)
# x = tf.keras.layers.experimental.preprocessing.Resizing(
# *size_before3[1:3], interpolation="bilinear"
# )(x)
size_tmp = (size_before3[1], size_before3[2])
x = tf.image.resize(x, size_tmp)
# Ensure that the model takes into account
# any potential predecessors of `input_tensor`.
if input_tensor is not None:
inputs = get_source_inputs(input_tensor)
else:
inputs = img_input
if activation in {'softmax', 'sigmoid'}:
x = tf.keras.layers.Activation(activation)(x)
model = Model(inputs, x, name='deeplabv3plus')
# load weights
if weights == 'pascal_voc':
if backbone == 'xception':
weights_path = get_file('deeplabv3_xception_tf_dim_ordering_tf_kernels.h5',
WEIGHTS_PATH_X,
cache_subdir='models')
else:
weights_path = get_file('deeplabv3_mobilenetv2_tf_dim_ordering_tf_kernels.h5',
WEIGHTS_PATH_MOBILE,
cache_subdir='models')
model.load_weights(weights_path, by_name=True)
elif weights == 'cityscapes':
if backbone == 'xception':
weights_path = get_file('deeplabv3_xception_tf_dim_ordering_tf_kernels_cityscapes.h5',
WEIGHTS_PATH_X_CS,
cache_subdir='models')
else:
print("deeplab_v3_plus.py: get_file deeplabv3_mobilenetv2_tf_dim_ordering_tf_kernels_cityscapes.h5")
weights_path = get_file('deeplabv3_mobilenetv2_tf_dim_ordering_tf_kernels_cityscapes.h5',
WEIGHTS_PATH_MOBILE_CS,
cache_subdir='models')
model.load_weights(weights_path, by_name=True)
return model
def preprocess_input(x):
"""Preprocesses a numpy array encoding a batch of images.
# Arguments
x: a 4D numpy array consists of RGB values within [0, 255].
# Returns
Input array scaled to [-1.,1.]
"""
return preprocess_input(x, mode='tf')