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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How does spatially white noise differ from diffuse noise

In noise reduction, having read that directivity index is used to reduce diffuse noise and white noise gain reduces spatially white noise, I would like to know the difference between both the noise ...
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3answers
94 views

why the ultasound image is noisy by speckle noise?

My first question : I want to know why an image is noisy ?. why the ultrasound, SAR and Laser... images are noisy by a multiplicative noise not an additive noise? Another question : So the ...
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20 views

Identify correlated colored noises that affect a signal

In the process of signal + noise, which is not stationary. In this case how could I a. determine what autocorrelated noise colors affect a signal. b. What mix of correlated colors affect the signal ...
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1answer
19 views

Denoising approach for a combination of several ADC voltage channles

I have 2 ADC channels of constant voltage measurement with small amount of high frequency noise only and no low frequency oscillations. The final signal should be the simple sum of those and denoised ...
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4answers
80 views

implementation of Fourier denoising with hard threshold

I just tried the Fourier denoising method with a hard threshold and my code is as follow: ...
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1answer
35 views

Smooth (not) equally-spaced signal strength data

I'm currently trying to reduce the noise in/smooth sampled signal strength data. The context is that I collected data from a transmitting device using bluetooth - the available data is basically a ...
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3answers
84 views

Removing periodic spike noise from ECG signal

The signal shown in the following figure is collected from a ECG sensor. The spike noise that is observed with a periodicity of 30 seconds was traced to the periodic blip of the LED as it draws ...
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1answer
66 views

How to make a plot of noise standard deviation sigma vs. brightness from a images?

Hi I don't know where to start from. I'm trying to implement a plot of noise with Matlab. I have found a plot of noise standard deviation sigma vs. brightness from a images like this. ...
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7 views

use of recurrence quantification analysis for deterministic signal identification and classification

The recurrence quantification analysis (RQA) is a method of nonlinear data analysis which quantifies the number and duration of recurrences of a dynamical system presented by its state space ...
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1answer
31 views

Nonlinear tricks for blocking wide band noise

Conventional methods of filtering allow one to block parts of a frequency band while passing others. But thinking outside of conventional means, and perhaps not based on any frequency methods at all, ...
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43 views

Motion artifact cancellation from ECG signal using 3-axis accelerometer data

I have a ECG signal measured as a test subject is performing 3 different activities - sitting, walking(2mph) and jogging(5mph) and also the corresponding 3-axis accelerometer(X,Y and Z) signals. I can ...
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1answer
55 views

1D filter for speed input and noisy position sensor

I was tasked with designing a filter to smooth out a translating table. The system, we command a speed and a desired position, and measure it with two noisy position sensors. The commanded speed is ...
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0answers
29 views

Sparse Signal Dense Noise

If I have a sparse signal contaminated with dense noise, and if I don't have a reference signal to help me, what techniques are suitable to recover the signal? I don't know what the original signal ...
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0answers
237 views

Calculating SNR for ECG signals

I'm reading through the literature for finding the best way to calculate SNR for a ECG signal. While there are many algorithms for improving SNR, I couldn't find any that details any standard ...
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0answers
70 views

Image denoising algorithm in matlab

I'm trying to denoise a grayscale image using the two level denoising algorithm as shown in the following block diagram. I used wiener filtering for denoising.Code is given below. ...
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0answers
89 views

Weighted Nuclear Norm Minimization for Image Denoising

Recently, I saw new published papers like this paper about denoising images using Weighted Nuclear Norm Minimization (WNNM) approach and I am wondering what is the physical intuition behind it. The ...
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2answers
200 views

Removal of noise from vibration recordings

Problem I am analyzing accelerometer recordings that are contaminated by 'spikes' caused by issues in the digital circuitry. The spikes are problematic, because I wish to determine the peak-amplitude ...
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0answers
91 views

Time frequency domain analyis of signals

In the time frequency domain I have used the following denoising methods Thresholding or schwirnking - Soft,Hard,Median and with methods (minimax, adaptative and sure). However if recomposing the ...
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1answer
189 views

Duration of unknown rectangular pulse with additive white Gaussian noise

Problem. There is a discrete signal $f[i]$ (example below). It is known, that $f[i]$ have a form of rectangular pulse with additive white Gaussian noise. $f[i] = s[i] + n[i]$, $s[i] = ...
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2answers
293 views

How to remove the noise without destroying the main edge?

I am working on a project. I want to segment a logo from a car and the picture's size is 3648*2432. The logo is selected by the red rectangle. I extracted this area and turn into gray level. The ...
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1answer
195 views

Denoise images with wavelets

I try to understand what following algorithm from this gimp plugin does to denoise an image: ...
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0answers
59 views

Adaptive Line noise removal using IIR notch filters

I'm trying to filter out line noise(60Hz and 120Hz) from a EEG signals received over a bluetooth link. I'm proposing to use a IIR notch filter to filter out the line-noise which varies w.r.t to ...
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0answers
45 views

What is the relation between Gaussian filter and Wiener filter?

These are probably quite obvious, but wanted to make sure I got them right. Let $f$ be the noisy version of $f_0$ to which noise $w$ has been added, i.e. $f = f_0 + w$ Weiner filter lets us obtain ...
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0answers
26 views

Derivative of a noisy signal with multiple samples

I am trying to find the best way to get a derivative from the shown signal. It consists of a number measuring positions, which each have been sampled 50 times and then gone to the next point. My ...
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18 views

Estimating plant parameters from noisy frequecy response data

I have to estimate the parameters of a 1st order transfer function, namely, the coefficients, through experiment. I ran a few experiments and I have a bunch of input-output data vectors. The ...
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50 views

Wavelet Denoising: Which thresholding method is considered good in this case?

I performed a routine MATLAB 1-D wavelet denoising using Daubechies 16 Wavelet at level 32 Example Code: ...
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2answers
199 views

Poisson noise and curve fitting - denoise first?

If I have an image that is severely corrupted by Poisson noise, and I want to fit a function to the image, is it "better" to attempt to denoise the signal first before fitting, or should I move ...
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106 views

separate signal values from noise

let us consider following graph of singular values i want to make some kind of clustering of these data,namely to seperate main components from non main components,let say signal components ...
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1answer
117 views

denosing given signal using wavelet

let us suppose that we have given following model $y(t)=A_1 \sin(\omega_1*t+\phi_1) + A_2 \sin(\omega_2*t+\phi_2) + A_3 \sin(\omega_3*t+\phi_3)+ \ldots +A_p \sin(\omega_p*t+\phi_p)+z(t)$ where ...
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2answers
584 views

Image Noise Detection Using MATLAB

I want to implement the following algorithm. Let $I$ denote noisy image and for each pixel of $I$ is represented by $I(x,y)$. A Sliding window of size $3\times3$ centered at $I(x, y)$ is ...
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2answers
780 views

What is the math behind median filter's noise reduction property?

I am interested in understanding the mathematical reason for why does applying a median filter on an image (or signal) result in reduction of noise.
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3answers
324 views

Which filters are the most commonly used and easier to implement for ECG noise removal?

ECG signal is affected by interferences such as the Powerline Interference, Baseline Wandering and Muscle Noise. There are many filters available which can reasonably cancel these types of noise. ...
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0answers
71 views

Algorithms for removing oscillations?

I am interested in removing oscillations from a signal to capture the lower-frequency variations, similar to the objective of this problem. The oscillations vary in frequency in the time domain, so ...
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1answer
123 views

Karhunen loeve transform question

I have read some about Karhunen-Loeve Transform (KLT) and its application to the field of seismic data processing. The method as I understand it based on decomposing the data (actually mostly used in ...
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2answers
460 views

Using Total Variation Denoising to clean accelerometer data

I know this is maybe a very basic question but I am doing this as a hobby and I can't find a solution to this problem. Basically I am trying to remove some noise from data I am reading from an ...
2
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1answer
124 views

Metrics for Noisy Images

I have a doubt. We calculate metrics such as PSNR, SNR, and MSE to prove that the proposed algorithm is better than its counterparts. To do this we need Original image (Noise free), Noisy image (we ...
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1answer
170 views

nonlocal means filtering technique

how is a non local means filter different from others such as: 1. Gaussian smoothing 2. total variation denoising
5
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1answer
331 views

Removing a sinusoidal artifact from a set of movie frames

I am doing some post-hoc analysis of a dataset consisting of a series of movie frames that are contaminated by a strongly periodic artifact. I would like to remove this artifact from my frames. For ...
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2answers
183 views

Bandpass filter on noisy sinusoid that predicts turning points

Is there an application where it is required to predict turning-points of a signal that is like a sinusoid with constant frequency, variable amplitude and some noise (Gaussian additive noise)? The ...
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2answers
2k views

Noise reduction from very noisy audio

I am trying to write an algorithm that would automatically segment a piece of audio with bird calls recordings. My input data are 1 minute-long wave files and on the output I would like to get ...
8
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1answer
159 views

Remove artifact from space probe image

This is a photo of our homeworld, taken by the Juno spacecraft recently, sling-shotting on its way to Jupiter. What it gained in speed, we lost in ours, however thankfully we will not be falling into ...
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0answers
242 views

Sine-weighted moving average on non-periodic, stationary signal

I am looking for -or trying to create- a filter with a piece-wise monotonic second derivative in such a way that when placed on a non-periodic input signal, changes in sign of the second derivative ...
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2answers
157 views

Image noise removal is part of image enhancement or image restoration? [closed]

I am working in digital image processing field, recently I am studying about Image Noise, I just want to know that whether this noise removal is part of image enhancement or image restoration. I ...
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2answers
431 views

what does musical noise sound like and is there a sample clip for it?

Musical residual noise is created when a noisy signal passes through a noise reduction algorithm. For instance, please see the paper: Esch, T; Vary, P: "Efficient Musical Noise Suppression for Speech ...
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0answers
236 views

Limitation of Wiener filter in image denoising

In image processing, up to which value of mean and variance can a Wiener filter be used to denoise the image? Wiener filtering can be used when variance of the noisy image is low, but I don't know ...
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1answer
138 views

Which anisotropic diffusion method is best for denoising now?

The best standard may be varing from PSNR to human's visual feeling. Any one is OK. I have tested J.Weickert's tensor diffusion and P&M's, they all can't satisfy me. Is there any anisotropic ...
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1answer
312 views

Removing surrounding noises from voice recording

I have a wave file whose frequency spectrum looks like this. It contains audio, which I want to keep while removing the rest. The problem is that the surround noise changes, just those distinct ...
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1answer
1k views

How one apply correctly FFT in image denoising

I'm writing program (Qt widgets/c++) for removing noise from images. As denoising method, i selected non local means method. This method has incredible quality of restored images (that's why it's the ...
4
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1answer
80 views

Spectral analysis of positive signals

Suppose that I have a sensor that can acquire samples $X[k]$ of the Fourier transform of an unknown signal $Y[t]$. An example is MRI, where the acquired data is in $k-$space. Now suppose that the ...
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1answer
254 views

How to denoise a conversation between two people?

I would like to know how to determine (using any programming language) whether a given audio file contains noise, such as of people talking in background, how to remove the noise, and how to ...