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Image Augmentor

This is a simple data augmentation tool for image files, intended for use with machine learning data sets. The tool scans a directory containing image files, and generates new images by performing a specified set of augmentation operations on each file that it finds. This process multiplies the number of training examples that can be used when developing a neural network, and should significantly improve the resulting network's performance, particularly when the number of training examples is relatively small.

Run the utility from the command-line as follows:

python main.py <image dir> <transform1> <transform2> ...

The <image dir> argument should be the path to a directory containing the image files to be augmented. The utility will search the directory recursively for files with any of the following extensions: jpg, jpeg, bmp, png.

The transform arguments determine what types of augmentation operations will be performed, using the codes listed in the table below:

Code Description Example Values
fliph Horizontal Flip fliph
flipv Vertical Flip flipv
noise Adds random noise to the image noise_0.01,noise_0.5
rot Rotates the image by the specified amount rot_90,rot_-45
trans Shifts the pixels of the image by the specified amounts in the x and y directions trans_20_10,trans_-10_0
zoom Zooms into the specified region of the image, performing stretching/shrinking as necessary zoom_0_0_20_20,zoom_-10_-20_10_10
blur Blurs the image by the specified amount blur_1.5

Each transform argument results in one additional output image being generated for each input image. An argument may consist of one or more augmentation operations. Multiple operations within a single argument must be separated by commas, and the order in which the operations are performed will match the order in which they are specified within the argument.

Examples

Produce 2 output images for each input image, one of which is flipped horizontally, and one of which is flipped vertically:

python main.py ./my_images fliph flipv

Produce 1 output image for each input image, by first rotating the image by 90° and then flipping it horizontally:

python main.py ./my_images rot_90,fliph

Operations

Horizontal Flip

Mirrors the image around a vertical line running through its center

python main.py ./my_images fliph

Original Image       Flipped Image

Vertical Flip

Mirrors the image around a horizontal line running through its center

python main.py ./my_images flipv

Original Image       Flipped Image

Noise

Adds random noise to the image. The amount of noise to be added is specified by a floating-point numeric value that is included in the transform argument, the numeric value must be greater than 0.

python main.py ./my_images noise_0.01 noise_0.02 noise_0.05

Original Image       Noisy Image       Noisy Image       Noisy Image

Rotate

Rotates the image. The angle of rotation is specified by an integer value that is included in the transform argument

python main.py ./my_images rot_90 rot_180 rot_-90

Original Image       Rotated Image       Rotated Image       Rotated Image

Translate

Performs a translation on the image. The size of the translation in the x and y directions are specified by integer values that are included in the transform argument

python main.py ./my_images trans_20_20 trans_0_100

Original Image       Translated Image       Translated Image

Zoom/Stretch

Zooms in (or out) to a particular area of the image. The top-left and bottom-right coordinates of the target region are specified by integer values included in the transform argument. By specifying a target region with an aspect ratio that differs from that of the source image, stretching transformations can be performed.

python main.py ./my_images zoom_150_0_300_150 zoom_0_50_300_150 zoom_200_0_300_300

Original Image       Zoomed Image       Stretched Image       Stretched Image

Blur

Blurs the image. The amount of blurring is specified by a floating-point value included in the transform argument.

python main.py ./my_images blur_1.0 blur_2.0 blur_4.0

Original Image       Blurred Image       Blurred Image       Blurred Image