tfAugmentor 1.2

An image augmentation library for tensorflow. Easy use with tf.data.Dataset

tfAugmentor

An image augmentation library for tensorflow. The libray is designed to be easily used with tf.data.Dataset. The augmentor accepts tf.data.Dataset object or a nested tuple of numpy array.

new features

• support tf 2.x
• API change for easier use, can directly process tf.data.Dataset object

Installation

tfAugmentor is written in Python and can be easily installed via:

pip install tfAugmentor

To run tfAugmentor properly, the following library should be installed as well:

• tensorflow (developed under tf 2.1), should work with 2.x version, 1.x version is not supported
• numpy (developed under numpy 1.18)

Quick Start

tfAugmentor is implemented to work seamlessly with tf.data. The tf.data.Dataset object can be directly processed by tfAugmentor. But you can also use it independently as a off-line augmentation tool.

To instantiate an Augmentor object, three arguments are required:

class Augmentor(object):
    def __init__(self, signature, image=[], label=[]):
		...

• signature: a nested tuple of string, representing the structure of the dataset to be processesd e.g. ('image', 'segmentation')
• image, label: only the items in these two lists will be augmented, segmentation masks should be put in the label list so that the labels will kept valid

simple example

import tfAugmentor as tfaug

# new tfAugmentor object
aug = tfaug.Augmentor(('image', 'semantic_mask'), image=['image'], label=['semantic_mask'])

# add augumentation operations
aug.flip_left_right(probability=0.5)
aug.rotate90(probability=0.5)
aug.elastic_deform(strength=2, scale=20, probability=1)

# assume we have three numpy arrays
X_image = ... # shape [batch, height, width, channel]
Y_semantic_mask = ... # shape [batch, height, width, 1]

# create tf.data.Dataset object
tf_dataset = tf.data.Dataset.from_tensor_slices((X_image, Y_semantic_mask)))
# do the actual augmentation
ds1 = aug(tf_dataset, keep_size=True)

# or you can directly pass the numpy arrays, a tf.data.Dataset object will be returned 
ds2 = aug((X_image, Y_semantic_mask)), keep_size=True)

If you pass the data as a python dictionary, the signature is not necessary any more. For example:

import tfAugmentor as tfaug

# new tfAugmentor object
aug = tfaug.Augmentor(image=['image'], label=['semantic_mask'])

# add augumentation operations
aug.flip_left_right(probability=0.5)
aug.rotate90(probability=0.5)
aug.elastic_deform(strength=2, scale=20, probability=1)

# assume we have three numpy arrays
X_image = ... # shape [batch, height, width, channel]
Y_semantic_mask = ... # shape [batch, height, width, 1]

ds_dict = {'image': X_image,
           'semantic_mask': Y_semantic_mask}
# create tf.data.Dataset object
tf_dataset = tf.data.Dataset.from_tensor_slices(ds_dict)
# do the actual augmentation
ds1 = aug(tf_dataset, keep_size=True)

# or directly pass the data
ds2 = aug(ds_dict, keep_size=True)

Note:

• All added augmentations will be executed one by one, but you can create multiply tfAugmentor to relize different augmentations in parallel
• all data should have a 4-D shape of [batch, height, width, channels] with the first dimension being the same, unprocessed items (itmes not in the 'image' or 'label' list) can have any dataset shape

complex example

import tfAugmentor as tfaug

# since 'class' is neither in 'image' nor in 'label', it will not be touched 
aug1 = tfaug.Augmentor((('image_rgb', 'image_depth'), ('semantic_mask', 'class')), image=['image_rgb', 'image_depth'], label=['semantic_mask'])
aug1 = tfaug.Augmentor((('image_rgb', 'image_depth'), ('semantic_mask', 'class')), image=['image_rgb', 'image_depth'], label=['semantic_mask'])

# add different augumentation operations to aug1 and aug2 
aug1.flip_left_right(probability=0.5)
aug1.random_crop_resize(sacle_range=(0.7, 0.9), probability=0.5)
aug2.elastic_deform(strength=2, scale=20, probability=1)

# assume we have the 1000 data samples
X_rgb = ...  # shape [1000 x 512 x 512 x 3]
X_depth = ... # shape [1000 x 512 x 512 x 1]
Y_semantic_mask = ... # shape [1000 x 512 x 512 x 1]
Y_class = ... # shape [1000 x 1]

# create tf.data.Dataset object
ds_origin = tf.data.Dataset.from_tensor_slices(((X_rgb, X_depth), (Y_semantic_mask, Y_class))))
# do the actual augmentation
ds1 = aug1(ds_origin, keep_size=True)
ds2 = aug2(ds_origin, keep_size=True)
# combine them
ds = ds_origin.concatenate(ds1)
ds = ds.concatenate(ds1)

Main Features

Mirroring

aug.flip_left_right(probability) # flip the image left right  
aug.flip_up_down(probability) # flip the image up down

Rotating

a.rotate90(probability) # rotate by 90 degree clockwise
a.rotate180(probability) # rotate by 180 degree clockwise
a.rotate270(probability) # rotate by 270 degree clockwise
a.rotate(angle, probability) # rotate by *angel* degree clockwise
a.random_rotate(probability) # randomly rotate the image

crop and resize

a.random_crop_resize(scale_range=(0.5, 0.8), probability) # randomly crop a sub-image and resize to the same size of the original image
a.random_crop_resize(scale_range=0.8, probability) # fixed crop size, random crop position

elastic deformation

a.elastic_deform(strength, scale, probability)