""" Tensorflow Preprocessing Adapter
Allows use of Tensorflow preprocessing pipeline in PyTorch Transform
Copyright of original Tensorflow code below.
Hacked together by / Copyright 2020 Ross Wightman
"""
# Copyright 2018 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.
# ==============================================================================
"""ImageNet preprocessing for MnasNet."""
import tensorflow.compat.v1 as tf
import numpy as np
IMAGE_SIZE = 224
CROP_PADDING = 32
tf.compat.v1.disable_eager_execution()
def distorted_bounding_box_crop(image_bytes,
bbox,
min_object_covered=0.1,
aspect_ratio_range=(0.75, 1.33),
area_range=(0.05, 1.0),
max_attempts=100,
scope=None):
"""Generates cropped_image using one of the bboxes randomly distorted.
See `tf.image.sample_distorted_bounding_box` for more documentation.
Args:
image_bytes: `Tensor` of binary image data.
bbox: `Tensor` of bounding boxes arranged `[1, num_boxes, coords]`
where each coordinate is [0, 1) and the coordinates are arranged
as `[ymin, xmin, ymax, xmax]`. If num_boxes is 0 then use the whole
image.
min_object_covered: An optional `float`. Defaults to `0.1`. The cropped
area of the image must contain at least this fraction of any bounding
box supplied.
aspect_ratio_range: An optional list of `float`s. The cropped area of the
image must have an aspect ratio = width / height within this range.
area_range: An optional list of `float`s. The cropped area of the image
must contain a fraction of the supplied image within in this range.
max_attempts: An optional `int`. Number of attempts at generating a cropped
region of the image of the specified constraints. After `max_attempts`
failures, return the entire image.
scope: Optional `str` for name scope.
Returns:
cropped image `Tensor`
"""
with tf.name_scope(scope, 'distorted_bounding_box_crop', [image_bytes, bbox]):
shape = tf.image.extract_jpeg_shape(image_bytes)
sample_distorted_bounding_box = tf.image.sample_distorted_bounding_box(
shape,
bounding_boxes=bbox,
min_object_covered=min_object_covered,
aspect_ratio_range=aspect_ratio_range,
area_range=area_range,
max_attempts=max_attempts,
use_image_if_no_bounding_boxes=True)
bbox_begin, bbox_size, _ = sample_distorted_bounding_box
# Crop the image to the specified bounding box.
offset_y, offset_x, _ = tf.unstack(bbox_begin)
target_height, target_width, _ = tf.unstack(bbox_size)
crop_window = tf.stack([offset_y, offset_x, target_height, target_width])
image = tf.image.decode_and_crop_jpeg(image_bytes, crop_window, channels=3)
return image
def _at_least_x_are_equal(a, b, x):
"""At least `x` of `a` and `b` `Tensors` are equal."""
match = tf.equal(a, b)
match = tf.cast(match, tf.int32)
return tf.greater_equal(tf.reduce_sum(match), x)
def _decode_and_random_crop(image_bytes, image_size, resize_method):
"""Make a random crop of image_size."""
bbox = tf.constant([0.0, 0.0, 1.0, 1.0], dtype=tf.float32, shape=[1, 1, 4])
image = distorted_bounding_box_crop(
image_bytes,
bbox,
min_object_covered=0.1,
aspect_ratio_range=(3. / 4, 4. / 3.),
area_range=(0.08, 1.0),
max_attempts=10,
scope=None)
original_shape = tf.image.extract_jpeg_shape(image_bytes)
bad = _at_least_x_are_equal(original_shape, tf.shape(image), 3)
image = tf.cond(
bad,
lambda: _decode_and_center_crop(image_bytes, image_size),
lambda: tf.image.resize([image], [image_size, image_size], resize_method)[0])
return image
def _decode_and_center_crop(image_bytes, image_size, resize_method):
"""Crops to center of image with padding then scales image_size."""
shape = tf.image.extract_jpeg_shape(image_bytes)
image_height = shape[0]
image_width = shape[1]
padded_center_crop_size = tf.cast(
((image_size / (image_size + CROP_PADDING)) *
tf.cast(tf.minimum(image_height, image_width), tf.float32)),
tf.int32)
offset_height = ((image_height - padded_center_crop_size) + 1) // 2
offset_width = ((image_width - padded_center_crop_size) + 1) // 2
crop_window = tf.stack([offset_height, offset_width,
padded_center_crop_size, padded_center_crop_size])
image = tf.image.decode_and_crop_jpeg(image_bytes, crop_window, channels=3)
image = tf.image.resize([image], [image_size, image_size], resize_method)[0]
return image
def _flip(image):
"""Random horizontal image flip."""
image = tf.image.random_flip_left_right(image)
return image
def preprocess_for_train(image_bytes, use_bfloat16, image_size=IMAGE_SIZE, interpolation='bicubic'):
"""Preprocesses the given image for evaluation.
Args:
image_bytes: `Tensor` representing an image binary of arbitrary size.
use_bfloat16: `bool` for whether to use bfloat16.
image_size: image size.
interpolation: image interpolation method
Returns:
A preprocessed image `Tensor`.
"""
resize_method = tf.image.ResizeMethod.BICUBIC if interpolation == 'bicubic' else tf.image.ResizeMethod.BILINEAR
image = _decode_and_random_crop(image_bytes, image_size, resize_method)
image = _flip(image)
image = tf.reshape(image, [image_size, image_size, 3])
image = tf.image.convert_image_dtype(
image, dtype=tf.bfloat16 if use_bfloat16 else tf.float32)
return image
def preprocess_for_eval(image_bytes, use_bfloat16, image_size=IMAGE_SIZE, interpolation='bicubic'):
"""Preprocesses the given image for evaluation.
Args:
image_bytes: `Tensor` representing an image binary of arbitrary size.
use_bfloat16: `bool` for whether to use bfloat16.
image_size: image size.
interpolation: image interpolation method
Returns:
A preprocessed image `Tensor`.
"""
resize_method = tf.image.ResizeMethod.BICUBIC if interpolation == 'bicubic' else tf.image.ResizeMethod.BILINEAR
image = _decode_and_center_crop(image_bytes, image_size, resize_method)
image = tf.reshape(image, [image_size, image_size, 3])
image = tf.image.convert_image_dtype(
image, dtype=tf.bfloat16 if use_bfloat16 else tf.float32)
return image
def preprocess_image(image_bytes,
is_training=False,
use_bfloat16=False,
image_size=IMAGE_SIZE,
interpolation='bicubic'):
"""Preprocesses the given image.
Args:
image_bytes: `Tensor` representing an image binary of arbitrary size.
is_training: `bool` for whether the preprocessing is for training.
use_bfloat16: `bool` for whether to use bfloat16.
image_size: image size.
interpolation: image interpolation method
Returns:
A preprocessed image `Tensor` with value range of [0, 255].
"""
if is_training:
return preprocess_for_train(image_bytes, use_bfloat16, image_size, interpolation)
else:
return preprocess_for_eval(image_bytes, use_bfloat16, image_size, interpolation)
class TfPreprocessTransform:
def __init__(self, is_training=False, size=224, interpolation='bicubic'):
self.is_training = is_training
self.size = size[0] if isinstance(size, tuple) else size
self.interpolation = interpolation
self._image_bytes = None
self.process_image = self._build_tf_graph()
self.sess = None
def _build_tf_graph(self):
with tf.device('/cpu:0'):
self._image_bytes = tf.placeholder(
shape=[],
dtype=tf.string,
)
img = preprocess_image(
self._image_bytes, self.is_training, False, self.size, self.interpolation)
return img
def __call__(self, image_bytes):
if self.sess is None:
self.sess = tf.Session()
img = self.sess.run(self.process_image, feed_dict={self._image_bytes: image_bytes})
img = img.round().clip(0, 255).astype(np.uint8)
if img.ndim < 3:
img = np.expand_dims(img, axis=-1)
img = np.rollaxis(img, 2) # HWC to CHW
return img