Question 1

What is epsilon in adversarial attacks?

Accepted Answer

Epsilon controls the magnitude of perturbation. Typical values range from 0.001 to 0.5. Higher epsilon increases attack strength but makes perturbation more visible.

Question 2

How is perturbation visibility estimated?

Accepted Answer

We use the ratio of L2 norm to total pixels. Imperceptible < 0.03, noticeable 0.03–0.1, visible > 0.1. This is a simplified perceptual proxy.

Question 3

What defenses work against FGSM?

Accepted Answer

Adversarial training, gradient masking, input preprocessing (JPEG compression, bit-depth reduction) and defensive distillation.

⚡ Adversarial Perturbation Calculator

🛡️ Defense recommendation (PGD)