Computer Vision Foundations · 免费预览

混叠攻击

一个微小的步长卷积网络会把不可见的奈奎斯特扰动转化为完全错误的输出，从而使混叠成为一个安全问题。

1. A tiny network that sees less than we do

A tiny network that sees less than we do

2. Hiding a pattern at Nyquist

Hiding a pattern at Nyquist

3. Decimation folds it down

Decimation folds it down

4. Aliasing is a security issue

Aliasing is a security issue

5. Where the attack lives

The adversarial pattern $z[n,m] = (-1)^n(-1)^m\,\ell_{\text{hidden}}[n,m]$ is added to an image at strength $0.05$ . Why does it go unnoticed in the input image?

6. What decimation does to the pattern

After the decimation step $h[n,m] = u[2n,2m]$ , what has happened to the spectral content of the hidden pattern that lived at Nyquist in the input?

7. Frequency of the attack

A perturbation flips sign at every pixel in both the horizontal and the vertical direction, alternating $+,-,+,-$ as $n$ and $m$ increase. Expressed in cycles per pixel, what is its spatial frequency along one axis? Write it as a decimal.

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