# Signal and Image Processing

**URL:** https://discourse.julialang.org/c/domain/dsp/26.md?page=3

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**Page:** 4

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## [Strided convolutions](https://discourse.julialang.org/t/strided-convolutions/91603)

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**Author:** [@cvikas](https://discourse.julialang.org/u/cvikas)\
**Replies:** 0\
**Last updated:** [December 13, 2022, 1:41pm UTC](https://discourse.julialang.org/t/strided-convolutions/91603 "2022-12-13T13:41:53Z")

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Hi everyone, Is there a package that facilitates strided convolution with user specific filter. I see that there is an implementation in Flux.jl, but I would like to use it s a function with the given stride and filter …

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## [How to base64 encode a rasterized image for embedding it into SVG?](https://discourse.julialang.org/t/how-to-base64-encode-a-rasterized-image-for-embedding-it-into-svg/90848)

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**Author:** [@fatteneder](https://discourse.julialang.org/u/fatteneder)\
**Replies:** 7\
**Last updated:** [November 26, 2022, 3:15pm UTC](https://discourse.julialang.org/t/how-to-base64-encode-a-rasterized-image-for-embedding-it-into-svg/90848 "2022-11-26T15:15:30Z")

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Below I try to do this using just the Base64 module. MWE using Base64 using Downloads using FileIO path = Downloads.download("https://github.com/MakieOrg/Makie.jl/raw/master/assets/doge.png") img = load(path) # reduc…

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## [How do frequencies shift after a FFT?](https://discourse.julialang.org/t/how-do-frequencies-shift-after-a-fft/88089)

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**Author:** [@bertulli](https://discourse.julialang.org/u/bertulli)\
**Replies:** 11\
**Last updated:** [October 9, 2022, 6:22pm UTC](https://discourse.julialang.org/t/how-do-frequencies-shift-after-a-fft/88089 "2022-10-09T18:22:26Z")

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Hi all! I hope this is the right subcategory to ask in. I’m playing around with the FFTW package to perform some Fourier transforms. I got how to define a signal and transform it, but I can’t get how (and why) can I shi…

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## [Comparison of different fft-implementations](https://discourse.julialang.org/t/comparison-of-different-fft-implementations/86021)

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**Author:** [@ellocco](https://discourse.julialang.org/u/ellocco)\
**Replies:** 11\
**Last updated:** [October 7, 2022, 10:00pm UTC](https://discourse.julialang.org/t/comparison-of-different-fft-implementations/86021 "2022-10-07T22:00:26Z")

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Hi, I am struggling with fft-analysis of real-world data. Main objective are correct results. Currently I use two different fft-implementations: FFTW.fft() SciPy.fft.fft() The reason for this is that FFTW.fft() see…

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## [ImageFeatures.hough\_circle\_gradient example is broken](https://discourse.julialang.org/t/imagefeatures-hough-circle-gradient-example-is-broken/87636)

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**Author:** [@Ondo](https://discourse.julialang.org/u/Ondo)\
**Replies:** 2\
**Last updated:** [September 22, 2022, 5:49pm UTC](https://discourse.julialang.org/t/imagefeatures-hough-circle-gradient-example-is-broken/87636 "2022-09-22T17:49:27Z")

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I really want to build something on the “find all circles in image” example seen near the bottom of this web-page: Function reference · ImageFeatures Initially it worked with the provided image but gave rise to errors w…

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## [Video Frame Stacking for Nightsky videos](https://discourse.julialang.org/t/video-frame-stacking-for-nightsky-videos/87211)

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**Author:** [@Allan\_Baker](https://discourse.julialang.org/u/Allan_Baker)\
**Replies:** 0\
**Last updated:** [September 13, 2022, 12:15pm UTC](https://discourse.julialang.org/t/video-frame-stacking-for-nightsky-videos/87211 "2022-09-13T12:15:12Z")

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Anyone using Julia to do frame stacking to enhance night images of the sky from Webcams or Iphones, etc.

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## [Playing/recording signals with PortAudio.jl](https://discourse.julialang.org/t/playing-recording-signals-with-portaudio-jl/85878)

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**Author:** [@Thomas\_Lei](https://discourse.julialang.org/u/Thomas_Lei)\
**Replies:** 3\
**Last updated:** [August 19, 2022, 6:46pm UTC](https://discourse.julialang.org/t/playing-recording-signals-with-portaudio-jl/85878 "2022-08-19T18:46:59Z")

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Hi all, I’m trying to use PortAudio.jl to stream and record audio signals. What I try to achieve is playing a signal through a loudspeaker and record this same signal through a mic. Basically, I want to record what I’m…

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## [How to take the 3D fft of a vector?](https://discourse.julialang.org/t/how-to-take-the-3d-fft-of-a-vector/85669)

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**Author:** [@Nic\_Leblanc](https://discourse.julialang.org/u/Nic_Leblanc)\
**Replies:** 8\
**Last updated:** [August 12, 2022, 6:22pm UTC](https://discourse.julialang.org/t/how-to-take-the-3d-fft-of-a-vector/85669 "2022-08-12T18:22:44Z")

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Hi all, I was wondering if there were a way to take the 3D fft of a vector. I am obviously using FFTW for my direct fft calculations using plans but I’m not sure for it to calculate the 3D fft and not just a 1D fft. The…

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## [Find Power Spectrum and Density](https://discourse.julialang.org/t/find-power-spectrum-and-density/85415)

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**Author:** [@natgeo-wong](https://discourse.julialang.org/u/natgeo-wong)\
**Replies:** 4\
**Last updated:** [August 7, 2022, 5:58am UTC](https://discourse.julialang.org/t/find-power-spectrum-and-density/85415 "2022-08-07T05:58:54Z")

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Hi! I have a set of time-series data. I’d just like to ask, are there packages available to decompose the signal into the power spectrum and the density/amplitude? And also, I would like to ask if there is a way to do…

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## [Image Partition into Blocks](https://discourse.julialang.org/t/image-partition-into-blocks/85238)

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**Author:** [@lgmendes](https://discourse.julialang.org/u/lgmendes)\
**Replies:** 3\
**Last updated:** [August 3, 2022, 6:36pm UTC](https://discourse.julialang.org/t/image-partition-into-blocks/85238 "2022-08-03T18:36:48Z")

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What is the equivalent Julia function of the Wolfram Mathematica ImagePartition function ( ImagePartition—Wolfram Language Documentation )

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## [Optimal Power of N for FFTW](https://discourse.julialang.org/t/optimal-power-of-n-for-fftw/85232)

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**Author:** [@Jake](https://discourse.julialang.org/u/Jake)\
**Replies:** 10\
**Last updated:** [August 3, 2022, 6:05pm UTC](https://discourse.julialang.org/t/optimal-power-of-n-for-fftw/85232 "2022-08-03T18:05:18Z")

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FFTW is fastest when it has small prime factors according to its manual. If there is the option to pad the input data, then with radix 2 FFT algorithms this is done with a “next power of 2” type function. However if th…

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## [Question about low pass filter in DSP.jl](https://discourse.julialang.org/t/question-about-low-pass-filter-in-dsp-jl/79214)

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**Author:** [@henry2004y](https://discourse.julialang.org/u/henry2004y)\
**Replies:** 5\
**Last updated:** [August 3, 2022, 10:00am UTC](https://discourse.julialang.org/t/question-about-low-pass-filter-in-dsp-jl/79214 "2022-08-03T10:00:16Z")

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Hi, I’m new to the domain of signal processing. Recently I have encountered some phase related issues with the low pass filter in DSP.jl. In MATLAB, fs = 1e3; t = 0:1/fs:1; % comment out random noise for testing x = \[…

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## [Inverse ICA for denoising](https://discourse.julialang.org/t/inverse-ica-for-denoising/84334)

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**Author:** [@nbagg](https://discourse.julialang.org/u/nbagg)\
**Replies:** 2\
**Last updated:** [July 19, 2022, 1:47pm UTC](https://discourse.julialang.org/t/inverse-ica-for-denoising/84334 "2022-07-19T13:47:14Z")

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Hi there, I am trying to use ICA to denoise an EEG signal. I am currently using the MultivariateStats.jl to perform the ICA: W = fit(ICA, data, num\_elec) This returns the mixing matrix as an ICA model. I want the inv…

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## [Is there Julia library for AI Image Denoising?](https://discourse.julialang.org/t/is-there-julia-library-for-ai-image-denoising/75688)

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**Author:** [@j\_u](https://discourse.julialang.org/u/j_u)\
**Replies:** 12\
**Last updated:** [July 18, 2022, 10:59pm UTC](https://discourse.julialang.org/t/is-there-julia-library-for-ai-image-denoising/75688 "2022-07-18T22:59:44Z")

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Actually, my question is like in the title. I am wondering if there is Julia library that makes Artificial Intelligence Image Denoising possible.

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## [I didn't ask for plan\_bfft, but got MethodError: no method matching plan\_bfft(::Vector{Number}, ::UnitRange{Int64})](https://discourse.julialang.org/t/i-didnt-ask-for-plan-bfft-but-got-methoderror-no-method-matching-plan-bfft-vector-number-unitrange-int64/82791)

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**Author:** [@Yly](https://discourse.julialang.org/u/Yly)\
**Replies:** 3\
**Last updated:** [June 16, 2022, 6:57am UTC](https://discourse.julialang.org/t/i-didnt-ask-for-plan-bfft-but-got-methoderror-no-method-matching-plan-bfft-vector-number-unitrange-int64/82791 "2022-06-16T06:57:24Z")

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While coding an iterative FFT function, I came upon a strange bug that depends on the arguments to the function in a complicated way. I’ve managed to reduce the problematic code to the following: using FFTW unitize(x::…

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## [FIR Filter Implementation in Julia](https://discourse.julialang.org/t/fir-filter-implementation-in-julia/81331)

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**Author:** [@duodenum](https://discourse.julialang.org/u/duodenum)\
**Replies:** 2\
**Last updated:** [May 20, 2022, 5:26am UTC](https://discourse.julialang.org/t/fir-filter-implementation-in-julia/81331 "2022-05-20T05:26:25Z")

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Hello all, I’m trying to replicate this MATLAB code in Julia for zero-phase filtering: d = designfilt('bandpassfir', 'StopbandFrequency1', 1e-9, ... 'PassbandFrequency1', 35, 'PassbandFrequency2', 45, ... 'Stop…

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## [Smoothing 2D data homogeneously regardless of resolution](https://discourse.julialang.org/t/smoothing-2d-data-homogeneously-regardless-of-resolution/80082)

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**Author:** [@Iddingsite](https://discourse.julialang.org/u/Iddingsite)\
**Replies:** 3\
**Last updated:** [May 3, 2022, 10:23am UTC](https://discourse.julialang.org/t/smoothing-2d-data-homogeneously-regardless-of-resolution/80082 "2022-05-03T10:23:22Z")

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Hi, I have 2D initial values for a model and I am trying to smooth it. I would say the easiest way is the apply a gaussian filter on it. My problem is that I don’t have the same resolution in y and in x. I would like to…

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## [Finding crossing points of two vectors of vertices](https://discourse.julialang.org/t/finding-crossing-points-of-two-vectors-of-vertices/15786)

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**Author:** [@jcook](https://discourse.julialang.org/u/jcook)\
**Replies:** 15\
**Last updated:** [March 8, 2022, 12:54pm UTC](https://discourse.julialang.org/t/finding-crossing-points-of-two-vectors-of-vertices/15786 "2022-03-08T12:54:32Z")

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Is there a tool out there that is able to find the locations of where two lines cross one another? By line I mean a vector of positions in the 2D plane, where the positions are connected by straight lines. I would prefer…

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## [Extract rpm from tachometer signal](https://discourse.julialang.org/t/extract-rpm-from-tachometer-signal/77329)

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**Author:** [@cmtasso](https://discourse.julialang.org/u/cmtasso)\
**Replies:** 14\
**Last updated:** [March 4, 2022, 11:15pm UTC](https://discourse.julialang.org/t/extract-rpm-from-tachometer-signal/77329 "2022-03-04T23:15:11Z")

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Hi guys… I need to extract a tachometer signal (pulses) and convert it to rpm. Would anyone know how to help write this script? In this case, the script is used within the Sigview software, which allows the use of the …

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## [M-sequences in Julia?](https://discourse.julialang.org/t/m-sequences-in-julia/76340)

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**Author:** [@KajWiik](https://discourse.julialang.org/u/KajWiik)\
**Replies:** 3\
**Last updated:** [February 13, 2022, 1:25pm UTC](https://discourse.julialang.org/t/m-sequences-in-julia/76340 "2022-02-13T13:25:35Z")

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Is there a package for generating m-sequences (Maximum length sequence - Wikipedia) in Julia? At least with a quick search I did not find anything.

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## [Sinc Interpolation based on FFT](https://discourse.julialang.org/t/sinc-interpolation-based-on-fft/52512)

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**Author:** [@roflmaostc](https://discourse.julialang.org/u/roflmaostc)\
**Replies:** 92\
**Last updated:** [January 24, 2022, 10:18pm UTC](https://discourse.julialang.org/t/sinc-interpolation-based-on-fft/52512 "2022-01-24T22:18:47Z")

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Hey, I was trying to implement a sinc interpolation based on FFTs. One way (as far as I know) is to zero pad the frequency spectrum and calculate the IFFT of the spectrum to get a sinc interpolated signal. I ended up …

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## [Show waveform as part of larger program](https://discourse.julialang.org/t/show-waveform-as-part-of-larger-program/72668)

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**Author:** [@Nenndul](https://discourse.julialang.org/u/Nenndul)\
**Replies:** 2\
**Last updated:** [December 6, 2021, 5:47pm UTC](https://discourse.julialang.org/t/show-waveform-as-part-of-larger-program/72668 "2021-12-06T17:47:54Z")

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I am using PortAudio to input and process an audio stream Just a very basic thing: stream = PortAudioStream("Microphone (5- UMC204HD 192k)", 1, 0) buf = read(stream, 5s) But when I use this inside of the larger progr…

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## [FFTX for Julia? (Spiral framework)](https://discourse.julialang.org/t/fftx-for-julia-spiral-framework/71533)

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**Author:** [@Perrin\_Meyer](https://discourse.julialang.org/u/Perrin_Meyer)\
**Replies:** 1\
**Last updated:** [November 16, 2021, 12:38am UTC](https://discourse.julialang.org/t/fftx-for-julia-spiral-framework/71533 "2021-11-16T00:38:35Z")

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LBNL and CMU appear to have a project to use CMU’s Spiral framework to generate efficient FFT libraries for CPU’s, GPU’s, etc. It’s a more recent project than FFTW, and unlike FFTW, the libraries are BSD licensed. Does…

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## [Consistent use of FilterCoefficients in DSP.jl?](https://discourse.julialang.org/t/consistent-use-of-filtercoefficients-in-dsp-jl/71119)

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**Author:** [@mbaz](https://discourse.julialang.org/u/mbaz)\
**Replies:** 0\
**Last updated:** [November 8, 2021, 1:22am UTC](https://discourse.julialang.org/t/consistent-use-of-filtercoefficients-in-dsp-jl/71119 "2021-11-08T01:22:53Z")

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In DSP.jl, some filter design commands return a filter object, while others (like remez) return a plain Float64 vector. This is inconvenient because many of the package functions don’t take vectors as arguments. I have …

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## [I have a hard time finding a good "upfirdn"](https://discourse.julialang.org/t/i-have-a-hard-time-finding-a-good-upfirdn/66540)

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**Author:** [@psteffensen](https://discourse.julialang.org/u/psteffensen)\
**Replies:** 6\
**Last updated:** [November 2, 2021, 12:52am UTC](https://discourse.julialang.org/t/i-have-a-hard-time-finding-a-good-upfirdn/66540 "2021-11-02T00:52:29Z")

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Hi, I am translating some code from Matlab to Julia and can’t find an equvalent to upfirdn. The only working option I have is to use PyCall and use the Python (SciPy) version. Like this: scipy\_signal = pyimport("scipy.…

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## [DSP package filt vs. filtfilt](https://discourse.julialang.org/t/dsp-package-filt-vs-filtfilt/69199)

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**Author:** [@Jake](https://discourse.julialang.org/u/Jake)\
**Replies:** 5\
**Last updated:** [October 4, 2021, 7:45pm UTC](https://discourse.julialang.org/t/dsp-package-filt-vs-filtfilt/69199 "2021-10-04T19:45:58Z")

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I am wondering how I need to modify the a and b vectors to make filtfilt give the same amplitude as filt. A minimum working example is: using DSP using Plots ω1 = 2 \* π \* 15 ω2 = 2 \* π \* 21 t = 0:1/400:1 fs = 1/(t\[2\]-…

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## [Resources for learning Julia coming from Python](https://discourse.julialang.org/t/resources-for-learning-julia-coming-from-python/67476)

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**Author:** [@garrek](https://discourse.julialang.org/u/garrek)\
**Replies:** 3\
**Last updated:** [September 2, 2021, 1:27am UTC](https://discourse.julialang.org/t/resources-for-learning-julia-coming-from-python/67476 "2021-09-02T01:27:26Z")

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I’m very new to Julia and I’m trying to find a go-to peak-finding implementation in one of the major Julia packages, but I can’t seem to find it. It seems there is a findlocalmaxima function in the Images package, but th…

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## [\[WIP\] Using Faust in Julia](https://discourse.julialang.org/t/wip-using-faust-in-julia/66271)

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**Author:** [@sletz](https://discourse.julialang.org/u/sletz)\
**Replies:** 4\
**Last updated:** [August 20, 2021, 3:52pm UTC](https://discourse.julialang.org/t/wip-using-faust-in-julia/66271 "2021-08-20T15:52:27Z")

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Faust (Functional Audio Stream) is a functional programming language for sound synthesis and audio processing with a strong focus on the design of synthesizers, musical instruments, audio effects, etc. Faust targets high…

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## [Loading touchstone (.snp) files](https://discourse.julialang.org/t/loading-touchstone-snp-files/66012)

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**Author:** [@Valery](https://discourse.julialang.org/u/Valery)\
**Replies:** 8\
**Last updated:** [August 13, 2021, 4:03am UTC](https://discourse.julialang.org/t/loading-touchstone-snp-files/66012 "2021-08-13T04:03:08Z")

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At the moment, what is the most convenient way to load touchstone (.snp) files in Julia ? I typically want to load scattering parameter of a multi-channel array extracted from software like Advanced Software Design (ADS…

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## [GSP Package](https://discourse.julialang.org/t/gsp-package/66132)

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**Author:** [@elefthca](https://discourse.julialang.org/u/elefthca)\
**Replies:** 2\
**Last updated:** [August 10, 2021, 8:40pm UTC](https://discourse.julialang.org/t/gsp-package/66132 "2021-08-10T20:40:48Z")

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Hello everyone! I recently became interested in Graph Signal Processing and upon searching, I found nothing relevant implemented in Julia. I also saw that the call for NumFocus grants opened just a couple of days ago wh…

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