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Results tagged with dft
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user 16212
The Discrete Fourier Transform (DFT) is a mapping between a finite set of discrete points in a (primal) domain (time, space) and the dual frequency domain. DFT requires an input sequence which is discrete, such as a sampling from an analogue audio signal.
2
votes
1
answer
1k
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How to perform a block-wise frequency down-shift?
I'm writing a Python function that shifts the frequency of an audio signal down to a specified range. I perform the downshift by multiplying the time series with a complex exponential, and then low-pa …
- 521
4
votes
Accepted
Computing cross-correlation of two images using OpenCV
DFT
int non_zero_rows = ( CORRELATE ) ? … ( img_in.rows + kernel.rows - 1 ) : ( img_in.rows );
cv::dft( dft_buf, dft_buf, 0, non_zero_rows );
cv::mulSpectrums( dft_buf, kernel_dft, dft_buf, 0, CORRELATE );
// Compute IDFT
dft( dft_buf, dft_buf …
- 521
5
votes
1
answer
12k
views
Computing cross-correlation of two images using OpenCV
I tried flipping the the kernel before computing the DFT, and that produces the correct cross-correlation. … cv::dft( dft_buf, dft_buf, 1, img_in.rows );
cv::mulSpectrums( dft_buf, kernel_dft, dft_buf, 0, CORRELATE );
dft( dft_buf, dft_buf, cv::DFT_INVERSE + cv::DFT_SCALE, kernel.rows/2 + img_in.rows );
int …
- 521