research/object_detection/predictors/heads/mask_head.py
# Copyright 2017 The TensorFlow Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
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# http://www.apache.org/licenses/LICENSE-2.0
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# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
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# ==============================================================================
"""Mask Head.
Contains Mask prediction head classes for different meta architectures.
All the mask prediction heads have a predict function that receives the
`features` as the first argument and returns `mask_predictions`.
"""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
import math
from six.moves import range
import tensorflow.compat.v1 as tf
import tf_slim as slim
from object_detection.predictors.heads import head
from object_detection.utils import ops
class MaskRCNNMaskHead(head.Head):
"""Mask RCNN mask prediction head.
Please refer to Mask RCNN paper:
https://arxiv.org/abs/1703.06870
"""
def __init__(self,
num_classes,
conv_hyperparams_fn=None,
mask_height=14,
mask_width=14,
mask_prediction_num_conv_layers=2,
mask_prediction_conv_depth=256,
masks_are_class_agnostic=False,
convolve_then_upsample=False):
"""Constructor.
Args:
num_classes: number of classes. Note that num_classes *does not*
include the background category, so if groundtruth labels take values
in {0, 1, .., K-1}, num_classes=K (and not K+1, even though the
assigned classification targets can range from {0,... K}).
conv_hyperparams_fn: A function to generate tf-slim arg_scope with
hyperparameters for convolution ops.
mask_height: Desired output mask height. The default value is 14.
mask_width: Desired output mask width. The default value is 14.
mask_prediction_num_conv_layers: Number of convolution layers applied to
the image_features in mask prediction branch.
mask_prediction_conv_depth: The depth for the first conv2d_transpose op
applied to the image_features in the mask prediction branch. If set
to 0, the depth of the convolution layers will be automatically chosen
based on the number of object classes and the number of channels in the
image features.
masks_are_class_agnostic: Boolean determining if the mask-head is
class-agnostic or not.
convolve_then_upsample: Whether to apply convolutions on mask features
before upsampling using nearest neighbor resizing. Otherwise, mask
features are resized to [`mask_height`, `mask_width`] using bilinear
resizing before applying convolutions.
Raises:
ValueError: conv_hyperparams_fn is None.
"""
super(MaskRCNNMaskHead, self).__init__()
self._num_classes = num_classes
self._conv_hyperparams_fn = conv_hyperparams_fn
self._mask_height = mask_height
self._mask_width = mask_width
self._mask_prediction_num_conv_layers = mask_prediction_num_conv_layers
self._mask_prediction_conv_depth = mask_prediction_conv_depth
self._masks_are_class_agnostic = masks_are_class_agnostic
self._convolve_then_upsample = convolve_then_upsample
if conv_hyperparams_fn is None:
raise ValueError('conv_hyperparams_fn is None.')
def _get_mask_predictor_conv_depth(self,
num_feature_channels,
num_classes,
class_weight=3.0,
feature_weight=2.0):
"""Computes the depth of the mask predictor convolutions.
Computes the depth of the mask predictor convolutions given feature channels
and number of classes by performing a weighted average of the two in
log space to compute the number of convolution channels. The weights that
are used for computing the weighted average do not need to sum to 1.
Args:
num_feature_channels: An integer containing the number of feature
channels.
num_classes: An integer containing the number of classes.
class_weight: Class weight used in computing the weighted average.
feature_weight: Feature weight used in computing the weighted average.
Returns:
An integer containing the number of convolution channels used by mask
predictor.
"""
num_feature_channels_log = math.log(float(num_feature_channels), 2.0)
num_classes_log = math.log(float(num_classes), 2.0)
weighted_num_feature_channels_log = (
num_feature_channels_log * feature_weight)
weighted_num_classes_log = num_classes_log * class_weight
total_weight = feature_weight + class_weight
num_conv_channels_log = round(
(weighted_num_feature_channels_log + weighted_num_classes_log) /
total_weight)
return int(math.pow(2.0, num_conv_channels_log))
def predict(self, features, num_predictions_per_location=1):
"""Performs mask prediction.
Args:
features: A float tensor of shape [batch_size, height, width, channels]
containing features for a batch of images.
num_predictions_per_location: Int containing number of predictions per
location.
Returns:
instance_masks: A float tensor of shape
[batch_size, 1, num_classes, mask_height, mask_width].
Raises:
ValueError: If num_predictions_per_location is not 1.
"""
if num_predictions_per_location != 1:
raise ValueError('Only num_predictions_per_location=1 is supported')
num_conv_channels = self._mask_prediction_conv_depth
if num_conv_channels == 0:
num_feature_channels = features.get_shape().as_list()[3]
num_conv_channels = self._get_mask_predictor_conv_depth(
num_feature_channels, self._num_classes)
with slim.arg_scope(self._conv_hyperparams_fn()):
if not self._convolve_then_upsample:
features = tf.image.resize_bilinear(
features, [self._mask_height, self._mask_width],
align_corners=True)
for _ in range(self._mask_prediction_num_conv_layers - 1):
features = slim.conv2d(
features,
num_outputs=num_conv_channels,
kernel_size=[3, 3])
if self._convolve_then_upsample:
# Replace Transposed Convolution with a Nearest Neighbor upsampling step
# followed by 3x3 convolution.
height_scale = self._mask_height // features.shape[1].value
width_scale = self._mask_width // features.shape[2].value
features = ops.nearest_neighbor_upsampling(
features, height_scale=height_scale, width_scale=width_scale)
features = slim.conv2d(
features,
num_outputs=num_conv_channels,
kernel_size=[3, 3])
num_masks = 1 if self._masks_are_class_agnostic else self._num_classes
mask_predictions = slim.conv2d(
features,
num_outputs=num_masks,
activation_fn=None,
normalizer_fn=None,
kernel_size=[3, 3])
return tf.expand_dims(
tf.transpose(mask_predictions, perm=[0, 3, 1, 2]),
axis=1,
name='MaskPredictor')
class ConvolutionalMaskHead(head.Head):
"""Convolutional class prediction head."""
def __init__(self,
is_training,
num_classes,
use_dropout,
dropout_keep_prob,
kernel_size,
use_depthwise=False,
mask_height=7,
mask_width=7,
masks_are_class_agnostic=False):
"""Constructor.
Args:
is_training: Indicates whether the BoxPredictor is in training mode.
num_classes: Number of classes.
use_dropout: Option to use dropout or not. Note that a single dropout
op is applied here prior to both box and class predictions, which stands
in contrast to the ConvolutionalBoxPredictor below.
dropout_keep_prob: Keep probability for dropout.
This is only used if use_dropout is True.
kernel_size: Size of final convolution kernel. If the
spatial resolution of the feature map is smaller than the kernel size,
then the kernel size is automatically set to be
min(feature_width, feature_height).
use_depthwise: Whether to use depthwise convolutions for prediction
steps. Default is False.
mask_height: Desired output mask height. The default value is 7.
mask_width: Desired output mask width. The default value is 7.
masks_are_class_agnostic: Boolean determining if the mask-head is
class-agnostic or not.
Raises:
ValueError: if min_depth > max_depth.
"""
super(ConvolutionalMaskHead, self).__init__()
self._is_training = is_training
self._num_classes = num_classes
self._use_dropout = use_dropout
self._dropout_keep_prob = dropout_keep_prob
self._kernel_size = kernel_size
self._use_depthwise = use_depthwise
self._mask_height = mask_height
self._mask_width = mask_width
self._masks_are_class_agnostic = masks_are_class_agnostic
def predict(self, features, num_predictions_per_location):
"""Predicts boxes.
Args:
features: A float tensor of shape [batch_size, height, width, channels]
containing image features.
num_predictions_per_location: Number of box predictions to be made per
spatial location.
Returns:
mask_predictions: A float tensors of shape
[batch_size, num_anchors, num_masks, mask_height, mask_width]
representing the mask predictions for the proposals.
"""
image_feature = features
# Add a slot for the background class.
if self._masks_are_class_agnostic:
num_masks = 1
else:
num_masks = self._num_classes
num_mask_channels = num_masks * self._mask_height * self._mask_width
net = image_feature
if self._use_dropout:
net = slim.dropout(net, keep_prob=self._dropout_keep_prob)
if self._use_depthwise:
mask_predictions = slim.separable_conv2d(
net, None, [self._kernel_size, self._kernel_size],
padding='SAME', depth_multiplier=1, stride=1,
rate=1, scope='MaskPredictor_depthwise')
mask_predictions = slim.conv2d(
mask_predictions,
num_predictions_per_location * num_mask_channels,
[1, 1],
activation_fn=None,
normalizer_fn=None,
normalizer_params=None,
scope='MaskPredictor')
else:
mask_predictions = slim.conv2d(
net,
num_predictions_per_location * num_mask_channels,
[self._kernel_size, self._kernel_size],
activation_fn=None,
normalizer_fn=None,
normalizer_params=None,
scope='MaskPredictor')
batch_size = features.get_shape().as_list()[0]
if batch_size is None:
batch_size = tf.shape(features)[0]
mask_predictions = tf.reshape(
mask_predictions,
[batch_size, -1, num_masks, self._mask_height, self._mask_width])
return mask_predictions
# TODO(alirezafathi): See if possible to unify Weight Shared with regular
# convolutional mask head.
class WeightSharedConvolutionalMaskHead(head.Head):
"""Weight shared convolutional mask prediction head."""
def __init__(self,
num_classes,
kernel_size=3,
use_dropout=False,
dropout_keep_prob=0.8,
mask_height=7,
mask_width=7,
masks_are_class_agnostic=False):
"""Constructor.
Args:
num_classes: number of classes. Note that num_classes *does not*
include the background category, so if groundtruth labels take values
in {0, 1, .., K-1}, num_classes=K (and not K+1, even though the
assigned classification targets can range from {0,... K}).
kernel_size: Size of final convolution kernel.
use_dropout: Whether to apply dropout to class prediction head.
dropout_keep_prob: Probability of keeping activiations.
mask_height: Desired output mask height. The default value is 7.
mask_width: Desired output mask width. The default value is 7.
masks_are_class_agnostic: Boolean determining if the mask-head is
class-agnostic or not.
"""
super(WeightSharedConvolutionalMaskHead, self).__init__()
self._num_classes = num_classes
self._kernel_size = kernel_size
self._use_dropout = use_dropout
self._dropout_keep_prob = dropout_keep_prob
self._mask_height = mask_height
self._mask_width = mask_width
self._masks_are_class_agnostic = masks_are_class_agnostic
def predict(self, features, num_predictions_per_location):
"""Predicts boxes.
Args:
features: A float tensor of shape [batch_size, height, width, channels]
containing image features.
num_predictions_per_location: Number of box predictions to be made per
spatial location.
Returns:
mask_predictions: A tensor of shape
[batch_size, num_anchors, num_classes, mask_height, mask_width]
representing the mask predictions for the proposals.
"""
mask_predictions_net = features
if self._masks_are_class_agnostic:
num_masks = 1
else:
num_masks = self._num_classes
num_mask_channels = num_masks * self._mask_height * self._mask_width
if self._use_dropout:
mask_predictions_net = slim.dropout(
mask_predictions_net, keep_prob=self._dropout_keep_prob)
mask_predictions = slim.conv2d(
mask_predictions_net,
num_predictions_per_location * num_mask_channels,
[self._kernel_size, self._kernel_size],
activation_fn=None, stride=1, padding='SAME',
normalizer_fn=None,
scope='MaskPredictor')
batch_size = features.get_shape().as_list()[0]
if batch_size is None:
batch_size = tf.shape(features)[0]
mask_predictions = tf.reshape(
mask_predictions,
[batch_size, -1, num_masks, self._mask_height, self._mask_width])
return mask_predictions