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Questions tagged [fourier-transform]

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Doing spectral analysis in GLSL, how can I get FFT-level fidelity in my results?

I'm using GLSL to do spectral analysis of an input signal. I do the math to associate each pixel (in a single row) with a frequency, then use [The Goertzel Algorithm][1] to determine the contribution ...
0 votes
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Is it possible to separate or split original images (or videos) from a blend image (or video)

The title says it all. Blended image or video contains multiple image or video blended on top of each other. I am looking for any software or tools that can separate the original images or videos. ...
1 vote
1 answer

How to calculate spatial frequency of an image just in one direction?

FFT spectra is not what is needed; what I need is a histogram showing which frequencies are there in image in horizontal direction, and which one is dominant Such spatial frequency is usually known ...
3 votes
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Sub-pixel image registration using phase

Currently I'm trying to reproduce the result by the academic papers Sub-pixel Shift Estimation of Image based on the Least Squares Approximation in Phase Region by Fujimoto, Fujisawa and Ikehara (...
7 votes
2 answers

Image rotation using FFT

I'm not sure how practical this might be but is it possible to use Fast Fourier Transform to rotate a raster image? To be honest, I never really understood FFT, but I saw it being used for JPEG, for ...
5 votes
1 answer

Why is spherical harmonics used in low frequency graphics data instead of a spherical Fourier transform?

I'm curious why spherical harmonics are commonly used in real time graphics instead of a spherical Fourier transform. I get that spherical harmonics are in a sort of frequency space (like FT is) so ...
14 votes
1 answer

How does a 2D Fourier Transform of an image work?

I understand how a 1D Fourier transform separates a signal into its component frequencies, but I'm having difficulty understanding how a 2D Fourier transform affects a 2D image. From another question,...