Questions tagged [denoising]

Denoising is a collection of techniques to remove unwanted noise from a signal. Typically this is done by filtering, but a variety of other techniques is available. Often combinations are used in sequence to optimize the denoising.

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60 views

How to remove heartbeat signal from blood pressure signal?

I am working on a medical engineering project that involves processing signals received from a human body. We use a sensor to record the blood pressure, $B(t)$. However, if you put your finger on many ...
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80 views

How to predict the final noise after adding two or more noisy discrete signals?

Is it possible to accurately predict the noise level if we add two or more noisy signals. For the sake of simplicity, let us say, the noise is independent and Gaussian. Suppose we wish to add signals $...
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Remove Noise from Discrete Signal with given Noise Model

I am interested in finding the true signal $p \in \mathbb{R}^D$ of an observed discrete signal $t \in \mathbb{Z}_{+}^D$. I know that each observed $t_{i}$ with $1 \leq i \leq D$ is the result of a ...
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How to Remove Temporal and Fixed Pattern Noise and Apply Tone Mapping?

I have a video, whose frames I have extracted and require to work with. 16 bits and grayscale images. My task is to improve the quality of the images, by removing the noise + adding tone mapping and ...
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Verifying if noise is gaussian in non-time series data

I'm trying to figure out if the noise in my experiments is gaussian or not. I don't have time series data. I first configure my system and then run some software application's and measure the average ...
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Directions on how to estimate the additive intensity bias

I have been reading this paper on how to estimate the additive intensity bias from an image, and I want to test it and write an algorithm for it. However, I can't seem to understand how to write the ...
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163 views

How to Solve Image Denoising with Total Variation Prior Using ADMM?

I was looking at some articles or Wikipedia on denoising images using the Total Variation norm. The setup is the Rudin Osher Fatemi (ROF) scheme, and the corresponding equation is: $$ F(u)=\int_{\...
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Digital Filters

If I want to remove the baseline drift in my ECG signal, which digital filter should be used without distortion and shift in my filtered output? What are the necessary things I have to look for the ...
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2answers
63 views

GPS | Retain Signal Tracking after Noise Bound

I have an IF data, 2 seconds signal sample from only one GPS satellite, I know the PRN number of the satellite. ...
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1answer
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How to filter sudden spikes and baseline changes in microphone signal?

The orange is a signal I recorded, the blue - my first restoration attempt, after which I decided to ask. The signal is audible, however there are 2 types of defects 1) baseline changes 2) sudden ...
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158 views

Pre-Processing Wi-Fi Channel State Information (CSI) Data

I was successfully able to collect some CSI data using the existing tool(s) on GitHub (https://github.com/StevenMHernandez/ESP32-CSI-Tool). The CSI data is a pair of imaginary and real number which ...
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Adding noise to real MRI data

I designed an algorithm for MRI data denoising which has good properties under heavy Rician noise (sigma is greater than 80). The method was tested on some phantoms and Rician noise generators. Now I ...
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Deconvolution of sidelobes in a point spread function?

It seems that most deconvolution algorithms mainly handle the main lobe of a point spread function (PSF) and assume that sidelobes can be safely neglected. For a direct algorithm trying to perform a ...
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Deep Learning for Online EEG Denoising

I'm currently working on the development of deep learning methods for online artifact removal from EEG signals. I'm interested in removing common biological artifacts such as EOG and EMG individually ...
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Is it possible to remove the non-random noise in the signal by averaging?

Ex: We're measuring vibration Frequency response of a structure, and at the same time there is a constant source of vibration (noise) from a pump. The pump is exciting the structure by sinusoid ...
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What is the advantage of Wiener filter for noise reduction of a 1D signal?

I have a 1D signal, acquired by an accelerator sensor that measure the vibration of a structure. What is the advantage of using a Wiener filter for noise reduction compared to the other (more classic) ...
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Time averaging denoising signal

I would like to use time averaging technique for denoising vibration signal, using the below function, how do we choose the appropriate parameters D and N for optimal denoising ! ...
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Noise removal where gains are >1

I am currently working on some noise removal algorithms and have come across what seems to be an oversight in the design of some of these algorithms. Two of the algorithms I am looking at use the PSD ...
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Training of adaptive filters

I am trying to understand adaptive filters as I want to implement a denoising algorithm based on them. Do we need to train all thee adaptive filters before they start their actual process? For the ...
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Logarithmic Amplitude Spectral Subtraction

I'm diving into audio processing and I'm trying to wrap my head around spectral subtraction. I learned there are different approaches do it based on power, magnitude, oversubtraction. My task is to ...
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1answer
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What is the best estimate of a signal given multiple noisy realisations

I assume that the noise corrupting the sought-for signal is [Edit: Gaussian] white noise of zero mean and unknown variance. Is the optimal solution simply the mean over the realisations (the ensemble ...
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Help with denoising signal and periodogram analysis resources

This is a cross posting from the crossvalidated stack exchange as I thought this may be a better forum to ask. I have a dataset consisting of respiratory time series signals of different lengths ...
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1answer
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What Are Intuitive Explanations for Shrinkage in the Context of Image Denoising?

I have occasionally come upon the term "shrinkage", mostly in the context of denoising methods. My rough understanding is that it refers to the part where the real distribution might not be ...
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Understanding noise removal method using wavelets

I am trying to understand how wavelet transform can be used to denoise a time series or signal and how to plot the scalogram image. My signal has a lot of fluctuations and as such I am finding it ...
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Enhancement by adaptive wavelet shrinkage denoising

I was wondering does anyone know any programming library or a way that can help me implement this algorithm.
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Seeking advice on how to denoise a video from poor CCTV lighting

I have grainy CCTV footage that will need some amount of clean up. I request for ideas on the best way to clean out the noise. I am attaching a frame extracted from the video here for hints on the ...
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Wavelet denoising. Simple explanation

I am studying wavelet transform. In the matlab in the "wavemenu" package, I use "SWT denoising 1-D". I loaded my signal, performed a Haar 5 wavelet squelch. I got a good result. I ...
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What are the wavelet packet functions and how are they different from the wavelet and scaling functions?

I understand that in the decomposition process, wavelet and scaling functions are used to split the signal to approximation and detail coefficients. Most of the time I saw the wavelet and scaling ...
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Removing Gaussian Noise from a Signal to Get Minimum Value

I have a signal that has a minimum value that I'm trying to read. The issue I'm having is that the signal is spread out by gaussian noise. I have the signal at a lot of timesteps (and expect the ...
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177 views

Implementation of Cepstrum in Python

Actually I want to denoise a signal. I know how can I implement FFT in python to denoise it. This is the implementation which I use(From this Kaggle notebook): But I don't know : How can I use ...
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Recommended Resources / Literature Search Terms for a Solutions to a Specific Kind of Multi Harmonic Signal Structure

Hopefully this isn't considered too off-topic. I'm working in industry these days and came up with a solution to a signal processing problem we'd been facing. I'd like to get a sense as to whether ...
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Why should wavelet re-synthesis produce an output when the main component is suppressed and what does this mean for denoising?

I understand that aliasing occurs in DWPT if the wavelet used is of low order since the "filters" are not perfect and the combination of down sampling and overlapping between bands causes ...
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222 views

A Simple Algorithm to Filter / Smooth / Denoise a Noisy Staircase Graph

Is there a way to remove the noise and smooth the graph into a staircase graph.
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Discrete wavelet center frequency

I am understanding that mother wavelets have a center frequency. Wavelets are limited in duration and oscillate then decay, so the center frequency is the mid pulse of the wavelet or so. But my ...
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How well can discrete wavelet packet transform reduce noises that are similar to the input signal in the same frequency band?

If I had 50Hz noise coming from power line, and signals in the same frequency range (EEG for example 0.1Hz to 100Hz). If my sampling frequency is 30kHz but I downsample my signal to 937kHz and use the ...
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1answer
42 views

Eroding noisy borders of polygons in an image

I am new to image processing, and this is the task at hand. I have a mask image of shape 500x500x1 that contains polygons. These polygons (=vector data: common term in remote sensing and GIS) are ...
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Best way to measure effectiveness of discrete wavelet denoising?

I am using matlab wavelet toolbox to denoise physiological signals, I am plotting the denoised signal on top of the original noisy signal and making sure spikes were not removed as a measure of ...
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1answer
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Automatic detection of noise-only segments in audio

This is my first question for this community. My connection to DSP comes via machine learning/deep learning, and I am working in the Python ecosystem. As a preprocessing step to audio classification, ...
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2answers
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Can discrete wavelet transform for denoising purposes be implemented in real time? [closed]

I have been researching effective algorithms for denoising biomedical signals (non-stationary) that can be implemented in real time either using FPGA or DSP. I can across many suggestions for ...
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1answer
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denoising floor function

Suppose that $y(t) = \lfloor x(t) + \epsilon(t) \rfloor$, where $\epsilon(t)$ is zero mean, independent noise. Is there any techniques on recovering $x(t)$ from $y(t)$?
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3answers
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Help with Audio Signal noise removing using FFT and IFFT in Matlab

I dont understand why my modified fft of a audio signal returns complex values after ifft. I modified my signal by zeroing out all the unnecessary freq. FFT: Fast fourier transfrom IFFT: Inverse ...
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Image Filtering by Averaging Similar Areas of the Same Image - Patch Based Processing

I heard of filtering algorithms which, to filter an image specific area, find similar areas in the image and average them to reduce the noice of the original area. E.g. an edge of a house can be more ...
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Processing Multiple Images to Detect Moving Object in Low SNR Conditions

I am new to this forum and new to the use of Fast Fourier transforms although I can program in Python 3 a bit. I have an unusual question and am seeking some general advice on (a) whether what I am ...
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3answers
351 views

best technique to remove noise from bio signal data

I'm still learning about signal processing so sorry if this is an intro problem. I want to remove noise from the following data so I can separate each wave and run analysis on it. The data is sampled ...
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208 views

Salt and Pepper impulse Denoising opencv

I am creating a generic method to work on salt and pepper noise and variants. The example images are as shown below : I tried few methods, such as ...
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Difference between "scaled white noise " vs. "unscaled white noise"

I have been searching Matlab user-guide for Wavelets. In their graphical user interface for denoising, there is an option for "unscaled white noise" and "scaled white noise" for the noise structure. ...
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How to get discrete values from a nosiy data set that have a trend?

I have a sensor that produces values over time (appr. 50/sec). I visualized these values (X axis is the time), this can be seen on the picture, measurement A and B - these are two independent ...
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image compression versus image denoising

Wavelet based image denoising may be performed by thresholding (selecting a threshold value, and discarding all values below the threshold. Wavelet-based image compression may also be performed by a ...
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redundancy of sin and cos waves with real data

I have the following question. Isn't it true that when applying a fourier transform to a real function (i.e. computing a characteristic function for a density), we only ever need one of the two waves: ...
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Running the BM3D Denoising Algorithm in Python

I am looking for a strong baseline in image denoising and therefore wanted to have the BM3D algorithm in my benchmark. These 2 python implementations: https://github.com/ericmjonas/pybm3d https://...