research/object_detection/builders/image_resizer_builder.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
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# 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
# limitations under the License.
# ==============================================================================
"""Builder function for image resizing operations."""
import functools
import tensorflow.compat.v1 as tf
from object_detection.core import preprocessor
from object_detection.protos import image_resizer_pb2
def _tf_resize_method(resize_method):
"""Maps image resize method from enumeration type to TensorFlow.
Args:
resize_method: The resize_method attribute of keep_aspect_ratio_resizer or
fixed_shape_resizer.
Returns:
method: The corresponding TensorFlow ResizeMethod.
Raises:
ValueError: if `resize_method` is of unknown type.
"""
dict_method = {
image_resizer_pb2.BILINEAR:
tf.image.ResizeMethod.BILINEAR,
image_resizer_pb2.NEAREST_NEIGHBOR:
tf.image.ResizeMethod.NEAREST_NEIGHBOR,
image_resizer_pb2.BICUBIC:
tf.image.ResizeMethod.BICUBIC,
image_resizer_pb2.AREA:
tf.image.ResizeMethod.AREA
}
if resize_method in dict_method:
return dict_method[resize_method]
else:
raise ValueError('Unknown resize_method')
def build(image_resizer_config):
"""Builds callable for image resizing operations.
Args:
image_resizer_config: image_resizer.proto object containing parameters for
an image resizing operation.
Returns:
image_resizer_fn: Callable for image resizing. This callable always takes
a rank-3 image tensor (corresponding to a single image) and returns a
rank-3 image tensor, possibly with new spatial dimensions.
Raises:
ValueError: if `image_resizer_config` is of incorrect type.
ValueError: if `image_resizer_config.image_resizer_oneof` is of expected
type.
ValueError: if min_dimension > max_dimension when keep_aspect_ratio_resizer
is used.
"""
if not isinstance(image_resizer_config, image_resizer_pb2.ImageResizer):
raise ValueError('image_resizer_config not of type '
'image_resizer_pb2.ImageResizer.')
image_resizer_oneof = image_resizer_config.WhichOneof('image_resizer_oneof')
if image_resizer_oneof == 'keep_aspect_ratio_resizer':
keep_aspect_ratio_config = image_resizer_config.keep_aspect_ratio_resizer
if not (keep_aspect_ratio_config.min_dimension <=
keep_aspect_ratio_config.max_dimension):
raise ValueError('min_dimension > max_dimension')
method = _tf_resize_method(keep_aspect_ratio_config.resize_method)
per_channel_pad_value = (0, 0, 0)
if keep_aspect_ratio_config.per_channel_pad_value:
per_channel_pad_value = tuple(keep_aspect_ratio_config.
per_channel_pad_value)
image_resizer_fn = functools.partial(
preprocessor.resize_to_range,
min_dimension=keep_aspect_ratio_config.min_dimension,
max_dimension=keep_aspect_ratio_config.max_dimension,
method=method,
pad_to_max_dimension=keep_aspect_ratio_config.pad_to_max_dimension,
per_channel_pad_value=per_channel_pad_value)
if not keep_aspect_ratio_config.convert_to_grayscale:
return image_resizer_fn
elif image_resizer_oneof == 'fixed_shape_resizer':
fixed_shape_resizer_config = image_resizer_config.fixed_shape_resizer
method = _tf_resize_method(fixed_shape_resizer_config.resize_method)
image_resizer_fn = functools.partial(
preprocessor.resize_image,
new_height=fixed_shape_resizer_config.height,
new_width=fixed_shape_resizer_config.width,
method=method)
if not fixed_shape_resizer_config.convert_to_grayscale:
return image_resizer_fn
elif image_resizer_oneof == 'identity_resizer':
def image_resizer_fn(image, masks=None, **kwargs):
del kwargs
if masks is None:
return [image, tf.shape(image)]
else:
return [image, masks, tf.shape(image)]
return image_resizer_fn
elif image_resizer_oneof == 'conditional_shape_resizer':
conditional_shape_resize_config = (
image_resizer_config.conditional_shape_resizer)
method = _tf_resize_method(conditional_shape_resize_config.resize_method)
if conditional_shape_resize_config.condition == (
image_resizer_pb2.ConditionalShapeResizer.GREATER):
image_resizer_fn = functools.partial(
preprocessor.resize_to_max_dimension,
max_dimension=conditional_shape_resize_config.size_threshold,
method=method)
elif conditional_shape_resize_config.condition == (
image_resizer_pb2.ConditionalShapeResizer.SMALLER):
image_resizer_fn = functools.partial(
preprocessor.resize_to_min_dimension,
min_dimension=conditional_shape_resize_config.size_threshold,
method=method)
else:
raise ValueError(
'Invalid image resizer condition option for '
'ConditionalShapeResizer: \'%s\'.'
% conditional_shape_resize_config.condition)
if not conditional_shape_resize_config.convert_to_grayscale:
return image_resizer_fn
elif image_resizer_oneof == 'pad_to_multiple_resizer':
pad_to_multiple_resizer_config = (
image_resizer_config.pad_to_multiple_resizer)
if pad_to_multiple_resizer_config.multiple < 0:
raise ValueError('`multiple` for pad_to_multiple_resizer should be > 0.')
else:
image_resizer_fn = functools.partial(
preprocessor.resize_pad_to_multiple,
multiple=pad_to_multiple_resizer_config.multiple)
if not pad_to_multiple_resizer_config.convert_to_grayscale:
return image_resizer_fn
else:
raise ValueError(
'Invalid image resizer option: \'%s\'.' % image_resizer_oneof)
def grayscale_image_resizer(image, masks=None):
"""Convert to grayscale before applying image_resizer_fn.
Args:
image: A 3D tensor of shape [height, width, 3]
masks: (optional) rank 3 float32 tensor with shape [num_instances, height,
width] containing instance masks.
Returns:
Note that the position of the resized_image_shape changes based on whether
masks are present.
resized_image: A 3D tensor of shape [new_height, new_width, 1],
where the image has been resized (with bilinear interpolation) so that
min(new_height, new_width) == min_dimension or
max(new_height, new_width) == max_dimension.
resized_masks: If masks is not None, also outputs masks. A 3D tensor of
shape [num_instances, new_height, new_width].
resized_image_shape: A 1D tensor of shape [3] containing shape of the
resized image.
"""
# image_resizer_fn returns [resized_image, resized_image_shape] if
# mask==None, otherwise it returns
# [resized_image, resized_mask, resized_image_shape]. In either case, we
# only deal with first and last element of the returned list.
retval = image_resizer_fn(image, masks)
resized_image = retval[0]
resized_image_shape = retval[-1]
retval[0] = preprocessor.rgb_to_gray(resized_image)
retval[-1] = tf.concat([resized_image_shape[:-1], [1]], 0)
return retval
return functools.partial(grayscale_image_resizer)