Johnny Corbino

2papers

2 Papers

3.9CVMay 12Code
A Mimetic Detector for Adversarial Image Perturbations

Johnny Corbino

Adversarial attacks fool deep image classifiers by adding tiny, almost invisible noise patterns to a clean image. The standard $\ell^\infty$-bounded attacks (FGSM, PGD, and the $\ell^\infty$ variant of Carlini--Wagner) produce high-frequency, near-random sign patterns at the pixel level: nearly invisible in $\ell^2$, but carrying disproportionate gradient energy. We exploit this with a single-shot, training-free detector using the high-order Corbino--Castillo mimetic operators from the open-source MOLE library. No retraining, no surrogate classifier, no access to the network under attack: the verdict is a property of the input alone, computed in $O(HW)$ time. We validate the detector on the standard \texttt{peppers} test image at the canonical $\ell^\infty$ budget $\varepsilon = 16/255$ and observe a clean-vs-adversarial separation that grows monotonically from $3.55\times$ at order $k=2$ to $4.19\times$ at $k=6$.

35.0NAMar 19
Solving Maxwell's Equations with Mimetic Methods

Johnny Corbino

We present a mimetic finite-difference approach for solving Maxwell's equations in one and two spatial dimensions. After introducing the governing equations and the classical Finite-Difference Time-Domain (FDTD) method, we describe mimetic operators that satisfy a discrete analogue of the extended Gauss divergence theorem and show how they lead to a compact, physically consistent formulation for computational electromagnetics. Two numerical examples are presented: a one-dimensional sinusoidal wave interacting with a lossy dielectric slab, and a two-dimensional Gaussian pulse with Uniaxial Perfectly Matched Layer (UPML) absorbing boundary conditions. All implementations use the Mimetic Operators Library Enhanced (MOLE).