Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

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.

2
votes
1answer
259 views

What Are the Differences between Super Resolution, Denoising and Deblurring?

In the fields of computer vision and image processing, what are the differences between Super Resolution, Denoising and Deblurring?
0
votes
1answer
18 views

How do you evaluate a denoising algorithm when all you have is the noisy data?

I'm currently working on denoising acoustic signal used in leak detection so that the leak detection could be more accurate. The thing is noise can come from various sources (Car or people passing by, ...
1
vote
1answer
53 views

How do I denoise a microscope image?

I'm working in a computer vision project, where the goal is to detect some specific parasites, but now that I have the images, I noticed that they have a watermark that specifies the microscope ...
8
votes
5answers
458 views

Estimators for improved spectral subtraction of noise

Real zero-mean Gaussian white noise, independent of a clean signal $x$ and of known variance is added to $x$ producing a noisy signal $y.$ Discrete Fourier transform (DFT) $Y$ of the noisy signal is ...
8
votes
2answers
3k views

When and how does one use a Wiener filter?

I'm trying to get some insight in this topic. As far as I understand, a determined signal enters a Wiener filter and the output is an estimate of some desired signal. Then, one can substract the ...
7
votes
4answers
283 views

Reducing noise from the same frequency band as signal

Sorry for the vague question (as I'm not even quite sure what I want to do is possible), just asking for some general direction to take my research. For a brief description, my signal resembles ...
1
vote
1answer
25 views

Isotropic and Anisotropic in the Total Variation Framework

The isotropic TV is defined as the estimation of 2-norm of gradients $\sqrt{(y_{i+1,j}-y_{i,j})^2+(y_{i,j+1}-y_{i,j})^2}$, while the anisotropic TV is defined as the estimation of 1-norm of gradients $...
0
votes
1answer
20 views

How to Remove the Patch Artifacts of Neural Network Denoising Process?

I have written a python script which uses the Noise2Noise: Learning Image Restoration without Clean Data implementation of the Auto Encoder which is useful to remove noise from images. In the original ...
1
vote
1answer
456 views

Real time background noise reduction or removal

I am trying to build a real time simple audio recognition that can recognize few keywords. Following this tensor flow tutorial i was able to train a simple neural network. Currently the signal flow ...
0
votes
1answer
44 views

Measure 3-D length using smart-phone's accelerometer

I'm wondering if we can measure 3-D length only by our smart-phone's accelerometer. And we all know these low cost IMUs are not accurate. You can model accelerometer's error this way: $$ a = f*a' + g ...
2
votes
1answer
122 views

Estimate smartphone accelerometer bias

I was planning to develop Android / iOS applications that enable users to measure 3D length using their smartphones. According to this question, you need to know at least the time-varying bias that ...
0
votes
0answers
8 views

Is the WTST-NST filter available as a module in some python library?

I need to implement the WTST-NST filter (wavelet transform based stationary non-stationary filter) to denoise some sound files (preferably in Python). I am from a Mechanical Engineering background ...
3
votes
1answer
580 views

Audio Signal Noise Filter Problem

I'm currently working with audio signals and have a problem: C = A*B + N, where C = recorded signal from microphone consisting of: A = known music file data played on speakers next to microphone ...
1
vote
1answer
504 views

How Does the Non Local Means Filter Work?

As I understand, A local mean filter is the one in which we take a pixel and calculate the mean of color-values of the pixels around them (but in a certain range of area) and the center pixel is ...
2
votes
2answers
1k views

Using MATLAB `xcorr()` to Find a Signal Hidden Behind Noise

I am trying to develop some code to find a transient signal in a data set I have. Before I get there however I am trying to write code using simulated data. I first am creating a signal with a ...
1
vote
2answers
91 views

How do I know if my EEG signal need denoising?

I recently started working on sleep study. For my research I download sleep EEG data from physionet. The EEG data has 100 Hz sampling rate and was recorded from 2 bipolar EEG site. When I start the ...
0
votes
0answers
19 views

Seperating two (image) signals in Fourier Space / Denoising

i have a problem here which is not so easy to solve. I have a measurement system which provides me two signals: -The "contrast" channel" - this is the main channel on the object -A second channel ...
0
votes
0answers
31 views

Calculating the Mean Square Error (MSE) in Wavelet Denoising

I´m currently reading the paper (to be more precise: it´s a chapter from the book "Shearlets, Multiscale Analysis of Multivariate Data" by Kutyniok and Labate) "Image Processing Using Shearlets" by G....
0
votes
0answers
36 views

Some difficult-to-approximate signals to test an signal extracting algorithm

I am searching for some strange signals in order to test an algorithm that I am developing. I've found an article by Donoho and Johnstone where they propose to test the algorithms using Blocks, Bumps, ...
0
votes
1answer
92 views

Are resolution increase and noise reduction from oversampling mutually exclusive?

Oversampling a signal means sampling it with a significantly higher sampling frequency than the Nyquist rate. As far as I know, there are three advantages: Easier design of anti alias filter Increase ...
-1
votes
1answer
67 views

Signal Denoising Uniformly in Frequency Domain

I have a noisy sparse signal containing number of frequency components. Is there any method to uniformly denoise this signal. in other words, a method that estimated and eliminates the noise power ...
0
votes
0answers
80 views

What is the best input for de-noising autoencoder for sound data?

I am currently trying to build an autoencoder to de-noise audio data. However I have not found any good articles explaining about the input to the autoencoder, i.e. feature vector. As in speech ...
0
votes
1answer
3k 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 ...
0
votes
0answers
27 views

Removing outlier data points from frequency-domain signal

Hello signal processing stack exchange, I have a complex frequency-domain signal representing the impulse response of a physical system over some range of frequency space. As an artifact of the ...
0
votes
0answers
21 views

Threshold both detail and analysis coefficients?

Suppose I perform a discrete wavelet transform on some noisy signal $x$ and obtain ${a_1, d_1, d_2, \ldots, d_n}$ where $a_1$ is the set of analysis coefficients and $\{d_j\}$ are the detail ...
7
votes
3answers
1k views

What is the difference between MSE and PSNR of images?

I have some doubts. What is the difference between quality parameters MSE and PSNR? Which is used when? Is there any advantage of PSNR over MSE or vice versa? Also I have heard people saying that ...
0
votes
1answer
20 views

Discretized Beltrami energy

In the paper "An Approach Based on Hybrid Genetic Algorithm Applied to Image Denoising Problem", I encounter this fitness function that by minimizing it, a denoised image of a noisy image is obtained. ...
2
votes
1answer
85 views

Denoising a signal using eigendecomposition

I have a complex observable series $Y(t)$ which is the result of summing two complex r.v $X(t)$ (unobservable) and a $\epsilon(t)$ (unobservable). $$Y(t)=X(t)+\epsilon(t)$$ Assume that $X$ and $\...
0
votes
2answers
62 views

Cascading a filter with itself to form a higher-order filter?

I've been given an audio signal with some high frequency noise. The professor gave me the system function of a lowpass filter that gives me control over the cutoff frequency: $$H(z)=\frac{1-\alpha}{2}...
2
votes
2answers
83 views

Recommended resources for noise reduction

I know the question What Resources Are Recommended for an Introduction to Signal Processing (DSP)? and I have already read some general DSP books, such as Rick Lyons's "Understanding DSP," and also ...
2
votes
1answer
72 views

Identifying whether or not a cyclostationary signal is noisy or not using the cyclic autocorrelation

I am trying to determine whether or not a given signal has been corrupted by Gaussian noise, either bandlimited (with a filter) or not. The signal in question is a BPSK or PAM signal that is upsampled ...
1
vote
2answers
538 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 from ...
0
votes
1answer
32 views

Denoising before or after Geometric Transform?

I am working on a image which needs denoising (bilateral filter) and a geometric transformation. I am not sure in which order these filters should be applied. Personally I think it is better to use ...
0
votes
1answer
89 views

What is the name of this very simple spectral subtraction technique?

Let $S = X + N$ be the sum of two audio signals $X$ and $N$ which are both stationnary (let's think X is a constant volume 440 Hz sinusoid and N is constant volume noise). If the sum S has a -20 dB ...
1
vote
2answers
537 views

Adaptive Gaussian Filter for Image Denoising

I am looking for methods to enhance noisy images, where: some pixels in the image are very noise, some other pixels do not contain so much noise. My first thought is to build an adaptive Gaussian ...
0
votes
2answers
185 views

Reducing Pepper Noise from an Image

For an image with pepper noise, presuming it is desirable to reduce the pepper noise, which operations, in which sequence, would you apply? Find an image, add pepper noise, and demonstrate your ...
3
votes
1answer
597 views

Denoise Image with Gaussian Noise Using MATLAB / Octave

I want to remove a noise for an image using MATLAB, when the observed image is $$f=u+v$$ where $u$ is the restored image (is the image i want recovered) and $v$ is the gaussian noise. To restore $u$,...
16
votes
2answers
15k views

Wiener Filter for Image Noise Reduction (Image Denoising)

I'm trying to get my head round the operation of the Wiener filter for the purpose of image noise reduction. In my case I'll have used another noise reduction filter first and will then use the result ...
-2
votes
2answers
239 views

Audio Denoising - Method which Extends the Naive Noise Reduction

Given an audio signal x[n] sampled at 44.1khz (let's say 1 minute of music or speech) and a noise template noise[n] (let's say 2 ...
4
votes
1answer
440 views

How Can I Use MATLAB to Solve a Total Variation Denoising Problem?

The Total Variation Denoising Problem is given by: $$ \arg \min_{x} \frac{1}{2} {\left\| A x - y \right\|}_{2}^{2} + \lambda \operatorname{TV} \left( x \right) $$ Where $ $ is the Total Variation ...
1
vote
4answers
4k 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. I'...
5
votes
1answer
358 views

Weighted Nuclear Norm Minimization for Image Denoising

Recently, I saw new published papers like Shuhang Gu, Lei Zhang, Wangmeng Zuo, Xiangchu Feng, Weighted Nuclear Norm Minimization with Application to Image Demonising [pdf]. about denoising images ...
2
votes
3answers
119 views

Denoise techniques when clean signal and pure noise is available

I have the clean version of the signal. I can obtain the environmental noise. I want to apply an effective denoising technique on a noisy signal (i.e., clean plus environmental noise). Some ...
6
votes
1answer
275 views

What is Super Resolution in the Context of Windowing?

I have been trying to understand what super-resolution is, in the context of DSP/DIP. What criteria is being maximized/minimized, and why? Most of my online searches yield super-res techniques from ...
7
votes
4answers
507 views

Solving Convex Optimization Problem Used for High Quality Denoising

The highest voted answer to this question suggests that to denoise a signal while preserving sharp transitions one should minimize the objective function: $$ |x-y|^2 + b|f(y)| $$ where $...
0
votes
2answers
364 views

Is Image Noise Removal Image Enhancement or Image Restoration Operation? [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 ...
1
vote
1answer
484 views

Which Anisotropic Diffusion Method is Best for Denoising Now?

The best standard may be varying 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 ...
0
votes
0answers
80 views

signal denoising by continuous wavelet transform

i want to use Morlet mother wavelet for signal denoising so i should employ cwt only. Is there any proper MATLAB code for this target?
0
votes
0answers
27 views

extract trend correctly, including most recent values

I'm looking to extract the trend of a signal. i've tried two methods for now, polynomial regression, and wavelet denoising both methods don't respect the computation of the last values (meaning the ...
3
votes
1answer
79 views

Measure the length of curves via a smartphone's accelerometer

Is it possible to measure the length of curves by moving a smartphone along them and processing the accelerometer's data? For example, measure the circumference of a circle of radius $8 \,\rm{cm}$. ...