# Filtering in the Frequency Domain

*Module of the free GPU.js GPGPU course · 5 tasks*

Convolution becomes multiplication — the trade that makes the FFT worth its complexity, plus the ringing, the wrap-around and the cross terms it hides.

## Tasks

1. [Convolution Becomes Multiplication](https://gpu.rocks/learn/frequency-filtering-8c225e10/1.md)
2. [The Brick Wall Rings](https://gpu.rocks/learn/frequency-filtering-8c225e10/2.md)
3. [Trade the Ringing for a Softer Edge](https://gpu.rocks/learn/frequency-filtering-8c225e10/3.md)
4. [A Tone Buried in Noise](https://gpu.rocks/learn/frequency-filtering-8c225e10/4.md)
5. [Multiplying Spectra Convolves in a Circle](https://gpu.rocks/learn/frequency-filtering-8c225e10/5.md)

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Interactive version: https://gpu.rocks/learn/frequency-filtering-8c225e10