This lecture focused on three major topics: some uses for Discrete Fourier Transforms (DFT), a derivation of the more efficent Fast Fourier Transforms FFT, and a discussion of Discrete Cosine Transforms (DCT).
Often it is much more efficent to transfer an image to the frequency domain to perform some digital image processing techniques on it. When this is the case converting to DFT is the simplest way to do this. Then came along FFT which does the same thing but with many less calculations. Then came along DCT which is a sort of side topic that does the same sort of thing, but without the complex numbers. DCT is often used in lossy image compression algorithms. The following links provide information on these transforms:
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