# Signal and Image Processing

**URL:** https://discourse.julialang.org/c/domain/dsp/26.md?page=2

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**Page:** 3

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## [Scalar indexing using broadcast notation?](https://discourse.julialang.org/t/scalar-indexing-using-broadcast-notation/107471)

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**Author:** [@nihil](https://discourse.julialang.org/u/nihil)\
**Replies:** 4\
**Last updated:** [December 12, 2023, 2:39am UTC](https://discourse.julialang.org/t/scalar-indexing-using-broadcast-notation/107471 "2023-12-12T02:39:52Z")

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I want to convert this to broadcast . notation indices = shuffle(\[(i, j) for i in 1:height for j in 1:width\]) for (i, j) in indices img\[i, j\] = sum(img .- (function.((img .- img\[i, j\])…

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## [Understanding the behaviour of Butterworth filter in DSP](https://discourse.julialang.org/t/understanding-the-behaviour-of-butterworth-filter-in-dsp/107396)

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**Author:** [@PeX](https://discourse.julialang.org/u/PeX)\
**Replies:** 3\
**Last updated:** [December 11, 2023, 12:57am UTC](https://discourse.julialang.org/t/understanding-the-behaviour-of-butterworth-filter-in-dsp/107396 "2023-12-11T00:57:52Z")

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Hi all, I’m using a highpass filter to isolate the oscillations from the trend in my signal. The filter I use for my time series signal is: response = Highpass((𝑓/1); fs) design = Butterworth(2) filtered = filt(digital…

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## [Spectral Coherence in Julia](https://discourse.julialang.org/t/spectral-coherence-in-julia/106144)

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**Author:** [@marianoarnaiz](https://discourse.julialang.org/u/marianoarnaiz)\
**Replies:** 27\
**Last updated:** [November 23, 2023, 9:14am UTC](https://discourse.julialang.org/t/spectral-coherence-in-julia/106144 "2023-11-23T09:14:14Z")

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Hi everyone, I am trying to do the spectral coherence between two signals in julia. Much like mscohere in Matlab. https://www.mathworks.com/help/signal/ug/measuring-signal-similarities.html I guess DSP.jl must have it,…

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## [Logarithmic Smoothing - A Tutorial and Two Package Ideas](https://discourse.julialang.org/t/logarithmic-smoothing-a-tutorial-and-two-package-ideas/84877)

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**Author:** [@LostInMusic](https://discourse.julialang.org/u/LostInMusic)\
**Replies:** 8\
**Last updated:** [November 16, 2023, 3:00am UTC](https://discourse.julialang.org/t/logarithmic-smoothing-a-tutorial-and-two-package-ideas/84877 "2023-11-16T03:00:29Z")

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As a person interested in acoustics, I often plot FFT results on double-logarithmic scales. The results are often pretty noisy and smoothing is typically applied, for example with a width of 1/12 octaves. Unfortunately, …

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## [How to display an image in full screen on a second monitor?](https://discourse.julialang.org/t/how-to-display-an-image-in-full-screen-on-a-second-monitor/100796)

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**Author:** [@marcsgil](https://discourse.julialang.org/u/marcsgil)\
**Replies:** 14\
**Last updated:** [November 7, 2023, 12:41pm UTC](https://discourse.julialang.org/t/how-to-display-an-image-in-full-screen-on-a-second-monitor/100796 "2023-11-07T12:41:27Z")

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Hello! I’m currently working on developing a program to control a Spatial Light Modulator (SLM), which is a lab equipment used in the field of Structured Light. Essentially, an SLM allows for the projection of interesti…

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## [Differentiable image values of a triangle](https://discourse.julialang.org/t/differentiable-image-values-of-a-triangle/105821)

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**Author:** [@Jakub\_Mitura](https://discourse.julialang.org/u/Jakub_Mitura)\
**Replies:** 3\
**Last updated:** [November 5, 2023, 8:43pm UTC](https://discourse.julialang.org/t/differentiable-image-values-of-a-triangle/105821 "2023-11-05T20:43:37Z")

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I have a 2D gray and white image and set of coordinates of triangles (generally all of the image is triangluted) is there a differentiable stable way to get mean and variance of the part of the image enclosed by each tr…

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## [How to find the best match for one image from an image set?](https://discourse.julialang.org/t/how-to-find-the-best-match-for-one-image-from-an-image-set/102705)

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**Author:** [@RunguangLi](https://discourse.julialang.org/u/RunguangLi)\
**Replies:** 12\
**Last updated:** [November 5, 2023, 3:44pm UTC](https://discourse.julialang.org/t/how-to-find-the-best-match-for-one-image-from-an-image-set/102705 "2023-11-05T15:44:42Z")

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Hi, I’m trying to find the best match for one image from an image set. Currently I use assess\_ssim function to do it. For example, img2 is clearly the best match for img1. But assess\_ssim gives very similar estimates for…

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## [Coherence between signals](https://discourse.julialang.org/t/coherence-between-signals/102772)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 14\
**Last updated:** [November 3, 2023, 2:09pm UTC](https://discourse.julialang.org/t/coherence-between-signals/102772 "2023-11-03T14:09:17Z")

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I have two signals, lets call them U\_1 and U\_2. Both are time series of wind speeds, measured at different locations. They are more or less coherent. What I would like to know is how does the coherence between these sign…

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## [How to detect oscillations/characteristic frequencies in data?](https://discourse.julialang.org/t/how-to-detect-oscillations-characteristic-frequencies-in-data/105169)

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**Author:** [@Torkel](https://discourse.julialang.org/u/Torkel)\
**Replies:** 5\
**Last updated:** [October 19, 2023, 7:37pm UTC](https://discourse.julialang.org/t/how-to-detect-oscillations-characteristic-frequencies-in-data/105169 "2023-10-19T19:37:33Z")

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I have a (many) signal I have gotten from experiments. The extent can be argued, but I’d definitely say there is something pulsing/oscillatory going on: using Plots plot(signal) How do I actually show this though? I …

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## [Displaying images with text](https://discourse.julialang.org/t/displaying-images-with-text/102694)

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**Author:** [@cpfiffer](https://discourse.julialang.org/u/cpfiffer)\
**Replies:** 16\
**Last updated:** [August 12, 2023, 11:35pm UTC](https://discourse.julialang.org/t/displaying-images-with-text/102694 "2023-08-12T23:35:22Z")

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I’m working on adapting the fast.ai fastbook with a few other people. You can find our work slowly happening via our website or by the Quarto book here. As part of this, I want to build a little tool to view images with…

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## [Image samples and derivatives for direct/photometric image alignment](https://discourse.julialang.org/t/image-samples-and-derivatives-for-direct-photometric-image-alignment/102214)

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**Author:** [@user664303](https://discourse.julialang.org/u/user664303)\
**Replies:** 6\
**Last updated:** [August 6, 2023, 6:03pm UTC](https://discourse.julialang.org/t/image-samples-and-derivatives-for-direct-photometric-image-alignment/102214 "2023-08-06T18:03:32Z")

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I’m planning to do some direct (or photometric) image alignment (or registration) in Julia. By this I mean methods based on the Lucas-Kanade method. For this I’ll need not only image samples at non-integer locations, but…

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## [DSSS encoding/ decoding](https://discourse.julialang.org/t/dsss-encoding-decoding/101857)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 1\
**Last updated:** [July 20, 2023, 11:47pm UTC](https://discourse.julialang.org/t/dsss-encoding-decoding/101857 "2023-07-20T23:47:49Z")

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Hello, I am trying to implement DSSS encoding/ decoding in Julia. Any hints how to start? Encoding: input: low frequent signal input: digital secret sequence filter: bandwidth filter output: analog (sampled) spread …

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## [How to generate white noise?](https://discourse.julialang.org/t/how-to-generate-white-noise/101673)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 1\
**Last updated:** [July 16, 2023, 12:38pm UTC](https://discourse.julialang.org/t/how-to-generate-white-noise/101673 "2023-07-16T12:38:24Z")

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I need some white noise, which I then can shape to have the required spectrum using filters. But how to I generate white noise? I could do it using rand or randn: noise1=rand(Int(1e6)).-0.5 noise2=randn(Int(1e6)) I ge…

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## [FFTW plan applied to array with wrong memory alignment](https://discourse.julialang.org/t/fftw-plan-applied-to-array-with-wrong-memory-alignment/101672)

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**Author:** [@ymtoo](https://discourse.julialang.org/u/ymtoo)\
**Replies:** 0\
**Last updated:** [July 16, 2023, 9:43am UTC](https://discourse.julialang.org/t/fftw-plan-applied-to-array-with-wrong-memory-alignment/101672 "2023-07-16T09:43:30Z")

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MWE: using ChainRulesCore: @ignore\_derivatives using DSP using DSP.Periodograms: forward\_plan using Zygote function mystft(x::AbstractVector{T}, n, noverlap) where {T} numsamples = length(x) numframes = numsamp…

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## [Detection of constant, weak signals](https://discourse.julialang.org/t/detection-of-constant-weak-signals/101022)

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**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 11\
**Last updated:** [July 3, 2023, 11:12am UTC](https://discourse.julialang.org/t/detection-of-constant-weak-signals/101022 "2023-07-03T11:12:50Z")

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I have the following problem: I have signal u(t), which can be sinus function, but I could also use any other function as exitation signal. I have a system which has a gain k between -1 and 1 and adds a strong noise …

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## [Displaying images in a grid layout?](https://discourse.julialang.org/t/displaying-images-in-a-grid-layout/100919)

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**Author:** [@amca01](https://discourse.julialang.org/u/amca01)\
**Replies:** 3\
**Last updated:** [June 29, 2023, 12:06am UTC](https://discourse.julialang.org/t/displaying-images-in-a-grid-layout/100919 "2023-06-29T00:06:29Z")

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What I’m after is a Julia equivalent to Matlab’s “subplots”, that allows images to be displayed in arbitrary grids. I can “stitch” two images of the same size with \[img1 img2\] as the last line of an IJulia cell. But …

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## [Arithmetic operations on an RGB image?](https://discourse.julialang.org/t/arithmetic-operations-on-an-rgb-image/100726)

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**Author:** [@amca01](https://discourse.julialang.org/u/amca01)\
**Replies:** 9\
**Last updated:** [June 27, 2023, 11:44pm UTC](https://discourse.julialang.org/t/arithmetic-operations-on-an-rgb-image/100726 "2023-06-27T23:44:49Z")

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Suppose I have an RGB image, imported with img = FileIO.load("image.png"); Then I have two questions: First, in Jupyter, using IJulia, how do I view a small subarray (say 3 x 3) as a set of numeric values? If img was…

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## [Lowpass with Hann window](https://discourse.julialang.org/t/lowpass-with-hann-window/100227)

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**Author:** [@ryofurue](https://discourse.julialang.org/u/ryofurue)\
**Replies:** 21\
**Last updated:** [June 15, 2023, 2:42am UTC](https://discourse.julialang.org/t/lowpass-with-hann-window/100227 "2023-06-15T02:42:38Z")

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I’m not familiar with “signal processing” business. I’m from a different discipline. That means I’m not familiar with the jargon in Filters - filter design and filtering · DSP.jl . I need to apply simple lowpass filters…

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## [Copy of Image](https://discourse.julialang.org/t/copy-of-image/99186)

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**Author:** [@SergeantMike67](https://discourse.julialang.org/u/SergeantMike67)\
**Replies:** 3\
**Last updated:** [May 23, 2023, 8:40pm UTC](https://discourse.julialang.org/t/copy-of-image/99186 "2023-05-23T20:40:33Z")

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I want to take an image and convert all colors to white leaving only the black pixels. I wrote the following code using Images pix=“” for pixel in pix

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## [How to use fft to 2d vector data](https://discourse.julialang.org/t/how-to-use-fft-to-2d-vector-data/98530)

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**Author:** [@xiaoming](https://discourse.julialang.org/u/xiaoming)\
**Replies:** 2\
**Last updated:** [May 10, 2023, 1:17am UTC](https://discourse.julialang.org/t/how-to-use-fft-to-2d-vector-data/98530 "2023-05-10T01:17:02Z")

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I have some data like this: function f(x) \[sin(2\*pi\*x\[1\])\*cos(2\*pi\*x\[2\]), cos(2\*pi\*x\[1\])\*sin(2\*pi\*x\[2\])\] end N=200 data = \[f(\[i/N,j/N\]) for i in 0:N-1, j in 0:N-1\] which is a matrix of size N\\times N, with vector e…

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## [Vectorization, or boundary tracing in julia](https://discourse.julialang.org/t/vectorization-or-boundary-tracing-in-julia/97638)

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**Author:** [@alex-s-gardner](https://discourse.julialang.org/u/alex-s-gardner)\
**Replies:** 10\
**Last updated:** [April 30, 2023, 4:14pm UTC](https://discourse.julialang.org/t/vectorization-or-boundary-tracing-in-julia/97638 "2023-04-30T16:14:38Z")

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Does anyone know of a julia package that can generate vectors/polygons (i,j) for the boundaries of areas found within a BitMatrix.

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## [Processing real-time streaming audio, controlled by a GUI](https://discourse.julialang.org/t/processing-real-time-streaming-audio-controlled-by-a-gui/96692)

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**Author:** [@cdevane](https://discourse.julialang.org/u/cdevane)\
**Replies:** 5\
**Last updated:** [April 21, 2023, 6:24am UTC](https://discourse.julialang.org/t/processing-real-time-streaming-audio-controlled-by-a-gui/96692 "2023-04-21T06:24:37Z")

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I’m a relative newcomer to Julia. I’d like to build an app that processes an audio stream in real time, with processing parameters controlled from a GUI. I’m looking for suggestions on how to approach this, or better ye…

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## [Are there any pertained models to generated image, text,video and audio embeddings in Julia ? If yes where can I find /download them to use?](https://discourse.julialang.org/t/are-there-any-pertained-models-to-generated-image-text-video-and-audio-embeddings-in-julia-if-yes-where-can-i-find-download-them-to-use/97408)

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**Author:** [@5hv5hvnk](https://discourse.julialang.org/u/5hv5hvnk)\
**Replies:** 2\
**Last updated:** [April 13, 2023, 9:04pm UTC](https://discourse.julialang.org/t/are-there-any-pertained-models-to-generated-image-text-video-and-audio-embeddings-in-julia-if-yes-where-can-i-find-download-them-to-use/97408 "2023-04-13T21:04:58Z")

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I want to find embedding of different type of datafiles and save them. Since I am quite new to Julia I am not being able to find appropriate models that does these tasks. Thank you

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## [Stockwell and inverse in Julia](https://discourse.julialang.org/t/stockwell-and-inverse-in-julia/97343)

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**Author:** [@marianoarnaiz](https://discourse.julialang.org/u/marianoarnaiz)\
**Replies:** 1\
**Last updated:** [April 11, 2023, 12:14pm UTC](https://discourse.julialang.org/t/stockwell-and-inverse-in-julia/97343 "2023-04-11T12:14:53Z")

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Hi all. Anyone has a code to do forward and inverse stockwell transform? Kind regards, M

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## [Stockwell Transform in Julia](https://discourse.julialang.org/t/stockwell-transform-in-julia/96847)

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**Author:** [@marianoarnaiz](https://discourse.julialang.org/u/marianoarnaiz)\
**Replies:** 1\
**Last updated:** [March 30, 2023, 5:17pm UTC](https://discourse.julialang.org/t/stockwell-transform-in-julia/96847 "2023-03-30T17:17:32Z")

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Hi all. Any one has a Stockwell Transform code? I need to apply it to denoise some time signals :slight\_smile: Thanks! https://en.wikipedia.org/wiki/S\_transform

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## [Filtering 2D data in Julia](https://discourse.julialang.org/t/filtering-2d-data-in-julia/94122)

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**Author:** [@marianoarnaiz](https://discourse.julialang.org/u/marianoarnaiz)\
**Replies:** 5\
**Last updated:** [February 6, 2023, 7:31pm UTC](https://discourse.julialang.org/t/filtering-2d-data-in-julia/94122 "2023-02-06T19:31:49Z")

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Hi all. Is there are packaga that I can use to filter 2D data? Things like butterworth filtering, derivatives, poly fitting, spectrum computation, etc? I know a lot of this is implemente in GMT.jl by @joa-quim but the …

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## [Interpolate a 3D array](https://discourse.julialang.org/t/interpolate-a-3d-array/93885)

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**Author:** [@Dale\_James\_Black](https://discourse.julialang.org/u/Dale_James_Black)\
**Replies:** 19\
**Last updated:** [February 3, 2023, 6:58pm UTC](https://discourse.julialang.org/t/interpolate-a-3d-array/93885 "2023-02-03T18:58:04Z")

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If I have a 3D array along with a unit normal vector and point for a plane that intersects that array, how would I use Interpolations.jl to create a new 3D array that is the same size as the original array but where all …

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## [Visualizing and understanding Fourier transforms](https://discourse.julialang.org/t/visualizing-and-understanding-fourier-transforms/93898)

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**Author:** [@skittishdev](https://discourse.julialang.org/u/skittishdev)\
**Replies:** 4\
**Last updated:** [February 2, 2023, 2:07pm UTC](https://discourse.julialang.org/t/visualizing-and-understanding-fourier-transforms/93898 "2023-02-02T14:07:38Z")

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Hi, I am trying to understand Fourier transforms, and decided to create some plots using Julia to help validate my own understanding. What I want Create a known signal as a sum/product of 2 other simple sinusoidal si…

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## [Implementing convolution from scratch](https://discourse.julialang.org/t/implementing-convolution-from-scratch/93723)

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**Author:** [@skittishdev](https://discourse.julialang.org/u/skittishdev)\
**Replies:** 5\
**Last updated:** [January 29, 2023, 9:43am UTC](https://discourse.julialang.org/t/implementing-convolution-from-scratch/93723 "2023-01-29T09:43:23Z")

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Hello, I already posted this question on Stackoverflow, but decided I’d ask here as well. Please find my question from Stackoverflow pasted below (verbatim). I am trying to implement convolution by hand in Julia. I’m …

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## [Raw file streaming read for SampledSignals](https://discourse.julialang.org/t/raw-file-streaming-read-for-sampledsignals/93125)

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**Author:** [@minetest2048](https://discourse.julialang.org/u/minetest2048)\
**Replies:** 0\
**Last updated:** [January 18, 2023, 3:57am UTC](https://discourse.julialang.org/t/raw-file-streaming-read-for-sampledsignals/93125 "2023-01-18T03:57:54Z")

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Is there a package where it implements something like GitHub - JuliaAudio/LibSndFile.jl: Julia Interface to libsndfile but with raw file, something like stream = loadstreaming("myfile.raw";format=Complex{Float32},n\_chan…

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