# Copyright 2020 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. # ============================================================================== """Keras image dataset loading utilities.""" import tensorflow.compat.v2 as tf # pylint: disable=g-classes-have-attributes import numpy as np from keras.layers.preprocessing import image_preprocessing from keras.preprocessing import dataset_utils from keras.preprocessing import image as keras_image_ops from tensorflow.python.util.tf_export import keras_export ALLOWLIST_FORMATS = ('.bmp', '.gif', '.jpeg', '.jpg', '.png') @keras_export('keras.utils.image_dataset_from_directory', 'keras.preprocessing.image_dataset_from_directory', v1=[]) def image_dataset_from_directory(directory, labels='inferred', label_mode='int', class_names=None, color_mode='rgb', batch_size=32, image_size=(256, 256), shuffle=True, seed=None, validation_split=None, subset=None, interpolation='bilinear', follow_links=False, crop_to_aspect_ratio=False, **kwargs): """Generates a `tf.data.Dataset` from image files in a directory. If your directory structure is: ``` main_directory/ ...class_a/ ......a_image_1.jpg ......a_image_2.jpg ...class_b/ ......b_image_1.jpg ......b_image_2.jpg ``` Then calling `image_dataset_from_directory(main_directory, labels='inferred')` will return a `tf.data.Dataset` that yields batches of images from the subdirectories `class_a` and `class_b`, together with labels 0 and 1 (0 corresponding to `class_a` and 1 corresponding to `class_b`). Supported image formats: jpeg, png, bmp, gif. Animated gifs are truncated to the first frame. Args: directory: Directory where the data is located. If `labels` is "inferred", it should contain subdirectories, each containing images for a class. Otherwise, the directory structure is ignored. labels: Either "inferred" (labels are generated from the directory structure), None (no labels), or a list/tuple of integer labels of the same size as the number of image files found in the directory. Labels should be sorted according to the alphanumeric order of the image file paths (obtained via `os.walk(directory)` in Python). label_mode: - 'int': means that the labels are encoded as integers (e.g. for `sparse_categorical_crossentropy` loss). - 'categorical' means that the labels are encoded as a categorical vector (e.g. for `categorical_crossentropy` loss). - 'binary' means that the labels (there can be only 2) are encoded as `float32` scalars with values 0 or 1 (e.g. for `binary_crossentropy`). - None (no labels). class_names: Only valid if "labels" is "inferred". This is the explicit list of class names (must match names of subdirectories). Used to control the order of the classes (otherwise alphanumerical order is used). color_mode: One of "grayscale", "rgb", "rgba". Default: "rgb". Whether the images will be converted to have 1, 3, or 4 channels. batch_size: Size of the batches of data. Default: 32. If `None`, the data will not be batched (the dataset will yield individual samples). image_size: Size to resize images to after they are read from disk. Defaults to `(256, 256)`. Since the pipeline processes batches of images that must all have the same size, this must be provided. shuffle: Whether to shuffle the data. Default: True. If set to False, sorts the data in alphanumeric order. seed: Optional random seed for shuffling and transformations. validation_split: Optional float between 0 and 1, fraction of data to reserve for validation. subset: One of "training" or "validation". Only used if `validation_split` is set. interpolation: String, the interpolation method used when resizing images. Defaults to `bilinear`. Supports `bilinear`, `nearest`, `bicubic`, `area`, `lanczos3`, `lanczos5`, `gaussian`, `mitchellcubic`. follow_links: Whether to visits subdirectories pointed to by symlinks. Defaults to False. crop_to_aspect_ratio: If True, resize the images without aspect ratio distortion. When the original aspect ratio differs from the target aspect ratio, the output image will be cropped so as to return the largest possible window in the image (of size `image_size`) that matches the target aspect ratio. By default (`crop_to_aspect_ratio=False`), aspect ratio may not be preserved. **kwargs: Legacy keyword arguments. Returns: A `tf.data.Dataset` object. - If `label_mode` is None, it yields `float32` tensors of shape `(batch_size, image_size[0], image_size[1], num_channels)`, encoding images (see below for rules regarding `num_channels`). - Otherwise, it yields a tuple `(images, labels)`, where `images` has shape `(batch_size, image_size[0], image_size[1], num_channels)`, and `labels` follows the format described below. Rules regarding labels format: - if `label_mode` is `int`, the labels are an `int32` tensor of shape `(batch_size,)`. - if `label_mode` is `binary`, the labels are a `float32` tensor of 1s and 0s of shape `(batch_size, 1)`. - if `label_mode` is `categorial`, the labels are a `float32` tensor of shape `(batch_size, num_classes)`, representing a one-hot encoding of the class index. Rules regarding number of channels in the yielded images: - if `color_mode` is `grayscale`, there's 1 channel in the image tensors. - if `color_mode` is `rgb`, there are 3 channel in the image tensors. - if `color_mode` is `rgba`, there are 4 channel in the image tensors. """ if 'smart_resize' in kwargs: crop_to_aspect_ratio = kwargs.pop('smart_resize') if kwargs: raise TypeError(f'Unknown keywords argument(s): {tuple(kwargs.keys())}') if labels not in ('inferred', None): if not isinstance(labels, (list, tuple)): raise ValueError( '`labels` argument should be a list/tuple of integer labels, of ' 'the same size as the number of image files in the target ' 'directory. If you wish to infer the labels from the subdirectory ' 'names in the target directory, pass `labels="inferred"`. ' 'If you wish to get a dataset that only contains images ' f'(no labels), pass `labels=None`. Received: labels={labels}') if class_names: raise ValueError('You can only pass `class_names` if ' f'`labels="inferred"`. Received: labels={labels}, and ' f'class_names={class_names}') if label_mode not in {'int', 'categorical', 'binary', None}: raise ValueError( '`label_mode` argument must be one of "int", "categorical", "binary", ' f'or None. Received: label_mode={label_mode}') if labels is None or label_mode is None: labels = None label_mode = None if color_mode == 'rgb': num_channels = 3 elif color_mode == 'rgba': num_channels = 4 elif color_mode == 'grayscale': num_channels = 1 else: raise ValueError( '`color_mode` must be one of {"rgb", "rgba", "grayscale"}. ' f'Received: color_mode={color_mode}') interpolation = image_preprocessing.get_interpolation(interpolation) dataset_utils.check_validation_split_arg( validation_split, subset, shuffle, seed) if seed is None: seed = np.random.randint(1e6) image_paths, labels, class_names = dataset_utils.index_directory( directory, labels, formats=ALLOWLIST_FORMATS, class_names=class_names, shuffle=shuffle, seed=seed, follow_links=follow_links) if label_mode == 'binary' and len(class_names) != 2: raise ValueError( f'When passing `label_mode="binary"`, there must be exactly 2 ' f'class_names. Received: class_names={class_names}') image_paths, labels = dataset_utils.get_training_or_validation_split( image_paths, labels, validation_split, subset) if not image_paths: raise ValueError(f'No images found in directory {directory}. ' f'Allowed formats: {ALLOWLIST_FORMATS}') dataset = paths_and_labels_to_dataset( image_paths=image_paths, image_size=image_size, num_channels=num_channels, labels=labels, label_mode=label_mode, num_classes=len(class_names), interpolation=interpolation, crop_to_aspect_ratio=crop_to_aspect_ratio) dataset = dataset.prefetch(tf.data.AUTOTUNE) if batch_size is not None: if shuffle: # Shuffle locally at each iteration dataset = dataset.shuffle(buffer_size=batch_size * 8, seed=seed) dataset = dataset.batch(batch_size) else: if shuffle: dataset = dataset.shuffle(buffer_size=1024, seed=seed) # Users may need to reference `class_names`. dataset.class_names = class_names # Include file paths for images as attribute. dataset.file_paths = image_paths return dataset def paths_and_labels_to_dataset(image_paths, image_size, num_channels, labels, label_mode, num_classes, interpolation, crop_to_aspect_ratio=False): """Constructs a dataset of images and labels.""" # TODO(fchollet): consider making num_parallel_calls settable path_ds = tf.data.Dataset.from_tensor_slices(image_paths) args = (image_size, num_channels, interpolation, crop_to_aspect_ratio) img_ds = path_ds.map( lambda x: load_image(x, *args), num_parallel_calls=tf.data.AUTOTUNE) if label_mode: label_ds = dataset_utils.labels_to_dataset(labels, label_mode, num_classes) img_ds = tf.data.Dataset.zip((img_ds, label_ds)) return img_ds def load_image(path, image_size, num_channels, interpolation, crop_to_aspect_ratio=False): """Load an image from a path and resize it.""" img = tf.io.read_file(path) img = tf.image.decode_image( img, channels=num_channels, expand_animations=False) if crop_to_aspect_ratio: img = keras_image_ops.smart_resize(img, image_size, interpolation=interpolation) else: img = tf.image.resize(img, image_size, method=interpolation) img.set_shape((image_size[0], image_size[1], num_channels)) return img