foolbox.adversarial

Provides a class that represents an adversarial example.

class foolbox.adversarial.Adversarial(model, criterion, original_image, original_class, distance=<class 'foolbox.distances.MeanSquaredDistance'>, threshold=None, verbose=False)[source]

Defines an adversarial that should be found and stores the result.

The Adversarial class represents a single adversarial example for a given model, criterion and reference image. It can be passed to an adversarial attack to find the actual adversarial.

Parameters:
model : a Model instance

The model that should be fooled by the adversarial.

criterion : a Criterion instance

The criterion that determines which images are adversarial.

original_image : a numpy.ndarray

The original image to which the adversarial image should be as close as possible.

original_class : int

The ground-truth label of the original image.

distance : a Distance class

The measure used to quantify similarity between images.

threshold : float or Distance

If not None, the attack will stop as soon as the adversarial perturbation has a size smaller than this threshold. Can be an instance of the Distance class passed to the distance argument, or a float assumed to have the same unit as the the given distance. If None, the attack will simply minimize the distance as good as possible. Note that the threshold only influences early stopping of the attack; the returned adversarial does not necessarily have smaller perturbation size than this threshold; the reached_threshold() method can be used to check if the threshold has been reached.

adversarial_class[source]

The argmax of the model predictions for the best adversarial found so far.

None if no adversarial has been found.

backward(gradient, image=None, strict=True)[source]

Interface to model.backward for attacks.

Parameters:
gradient : numpy.ndarray

Gradient of some loss w.r.t. the logits.

image : numpy.ndarray

Single input with shape as expected by the model (without the batch dimension).

Returns:
gradient : numpy.ndarray

The gradient w.r.t the image.

See also

gradient()

batch_predictions(images, greedy=False, strict=True, return_details=False)[source]

Interface to model.batch_predictions for attacks.

Parameters:
images : numpy.ndarray

Batch of inputs with shape as expected by the model.

greedy : bool

Whether the first adversarial should be returned.

strict : bool

Controls if the bounds for the pixel values should be checked.

channel_axis(batch)[source]

Interface to model.channel_axis for attacks.

Parameters:
batch : bool

Controls whether the index of the axis for a batch of images (4 dimensions) or a single image (3 dimensions) should be returned.

distance[source]

The distance of the adversarial input to the original input.

gradient(image=None, label=None, strict=True)[source]

Interface to model.gradient for attacks.

Parameters:
image : numpy.ndarray

Single input with shape as expected by the model (without the batch dimension). Defaults to the original image.

label : int

Label used to calculate the loss that is differentiated. Defaults to the original label.

strict : bool

Controls if the bounds for the pixel values should be checked.

has_gradient()[source]

Returns true if _backward and _forward_backward can be called by an attack, False otherwise.

image[source]

The best adversarial found so far.

normalized_distance(image)[source]

Calculates the distance of a given image to the original image.

Parameters:
image : numpy.ndarray

The image that should be compared to the original image.

Returns:
:class:`Distance`

The distance between the given image and the original image.

original_class[source]

The class of the original input (ground-truth, not model prediction).

original_image[source]

The original input.

output[source]

The model predictions for the best adversarial found so far.

None if no adversarial has been found.

predictions(image, strict=True, return_details=False)[source]

Interface to model.predictions for attacks.

Parameters:
image : numpy.ndarray

Single input with shape as expected by the model (without the batch dimension).

strict : bool

Controls if the bounds for the pixel values should be checked.

predictions_and_gradient(image=None, label=None, strict=True, return_details=False)[source]

Interface to model.predictions_and_gradient for attacks.

Parameters:
image : numpy.ndarray

Single input with shape as expected by the model (without the batch dimension). Defaults to the original image.

label : int

Label used to calculate the loss that is differentiated. Defaults to the original label.

strict : bool

Controls if the bounds for the pixel values should be checked.

reached_threshold()[source]

Returns True if a threshold is given and the currently best adversarial distance is smaller than the threshold.

target_class()[source]

Interface to criterion.target_class for attacks.