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Proximal operator of image Laplacian

Let $\alpha, \beta > 0$ and $\Delta := \nabla^T \nabla$ be the discrete laplacian operator, $$\nabla: \mathbb{R}^{n_x \times n_y \times n_z} \rightarrow \mathbb{R}^{3 \times n_x \times n_y \times ...
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2answers
79 views

Filtering noise from FFT, where noise is known to be shifted delta function

I have an input sequence $x=\{x_1, x_2 , ... x_n\}$ of reals, where $n=2^m$ for some $m$. I wish to calculate FFT of $x$. $X=FFT(x)$ However, before I calculate the FFT, the signal $x$ gets ...
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1answer
16 views

Pulse shaping and Baseband filtering

I'm slightly confused about baseband pulse shaping. Let's assume I have a complex data vector in an arbitrary complex constellation (QAM for example). I would like to pass this complex vector through ...
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1answer
74 views

How to filter almost periodic noise?

I have signal that looks like this: As you can see there are some almost periodic pulses at the background with amplitude about 1000. I am saying almost, because, if you zoom in, you may see that ...
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0answers
23 views

Open source GPS+IMU sensor fusion?

Are there any Open source implementations of GPS+IMU sensor fusion (loosely coupled; i.e. using GPS module output and 9 degree of freedom IMU sensors)? -- kalman filtering based or otherwise I see a ...
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2answers
57 views

Removing Bounded Noise from an Audio Signal

I'm currently trying to remove some noise from a "contaminated" audio file. From what's given, I know that the noise is isolated to a specific frequency band - that is, from ~1400 Hz - ~1800 Hz. The ...
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0answers
44 views

Median Filter for salt and pepper noise removal

Why median filter is considered as good for removal of salt and pepper noise? What are the other filters used for the same?
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1answer
31 views

Overlap/Chunk processing possible with Zero-phase?

I'm relatively new to DSP and I'm currently investigating FIR filter and IIR filters. From what I've found FIR filters can be implemented efficiently using the overlap-save method, but I was wondering ...
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0answers
48 views

Implementing a 2d butterworth filter for image processing?

I am at the moment trying to implement a bandpass butter worth filter which i then can use to apply on my original image. Problem is though My implementation of it using OpenCV doesn't seem to be ...
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0answers
9 views

Why would prefiltering measurement data affect the least squares estimate?

In estimating parameters in a discrete time model I've often seen the use of filters applied to the input data, before its applied to least squares processing. I've been told that the filters are ...
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1answer
87 views

Derive velocity and acceleration from position

I generate random spike data that represent the ouput from a rotary encoder. Here the output of my algorithm: The first plot is position, then velocity and then acceleration. Even though I downsample ...
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1answer
36 views

Filtering performance on Poisson noise with quadratic data-fidelity

We recently performed a work on signal filtering/component separation (sparse signal/trend/noise). The cost function contains: A quadratic data fidelity term, Some smoothed $\ell_1$ terms for ...
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1answer
61 views

How is the ends of a bandpass filtered signal reliable after applying the cosine taper?

A taper function decaying to zero at ends such as a cosine window is routinely applied to the signal before bandpass filtering to reduce end effects. Obviously the window alters the waveform. So, as ...
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1answer
79 views

Optimal windowing strategy for filtering live signal

I have a stream of 250 samples per second arriving at a pipeline stage which looks something like this simplified example. ...
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1answer
48 views

What is a 'notch' in image processing?

I cannot find out what does "notch" means in image processing? We have selective filters that one of the best of them is Notch filters. but what does the concept of "Notch"? why they are called ...
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1answer
30 views

How to reconstruct the signal if there were some temporary offsets

I am not a signal processing expert. I have data like this: where the red is what I have and the black is what I want to have. Any idea how to reconstruct this? The code for generating the data is ...
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0answers
43 views

Numerical noise in Butterworth filter

I am testing a digital Butterworth filter. This first example is a bandpass filter with a centre frequency of about 824 Hz. I generated this plot by calculating the Fourier transform of the filter ...
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0answers
33 views

Accurate Noisy Signal Filtering

I'm looking for some ideas to filter a noisy signal. my sampling Condition is : ...
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2answers
27 views

Adding channel effects to a signal

I have a a channel matrix "H" that is circulant. I have data blocks. I want to add the channel effects to the signal. When H was only a vector of channel coefficients I would say: ...
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0answers
16 views

Common spatial patterns explanation

Can anyone provide a lay explanation of what common spatial patterns are designed to do in EEG/BCI work? From what I understand, it is similar to PCA in that given 2 classes, it attempts to find a ...
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0answers
20 views

What is a Thresh filter?

I was looking at this site and saw the term. While I'm a bit familiar with some DSP terminology, I have never heard of this before. Google did not really help at all. From what the site explores, it ...
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0answers
72 views

What is Single pole filter?

Can anybody tell me why do we use single pole filter? And may be an example of Single pole filter in matlab. Good literature recommendations are also welcomed.Moreover, that would be good if anyone ...
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0answers
20 views

If a signal is added to another in the freq. domain, how to filter it out?

I have two signals, $x$ and $y$. I know that $F(x)=F(s)+F(n)$ and $F(y)=F(n)$, where $s$ is the 'clean' signal, $n$ is the added noise and $F$ donate Fourier Transform. To obtain the clean signal, I ...
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2answers
39 views

Can filter “depth” be adjusted by mixing dry and wet signals?

Can filter "depth" be adjusted by mixing dry and wet signals? I.e. can I simulate e.g. a +6dB bandshelf/peak filter at 1kHz by mixing in some of the dry unequalized signal and some of a wet signal ...
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2answers
129 views

MATLAB : How to filter a data signal

I have a data signal (column vector) with N values taken over at specific sample rate (dx) at a fixed frequency. After taking the Fourrier transform of this signal and representing it in the Fourier ...
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2answers
95 views

Filtering out a specific frequency in an analog signal

I'm wondering how I would go about filtering out a regular sine-wave signal with a constant frequency and voltage. I'm really new to the whole DSP-area but imagine I would have a regular sinewave at ...
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0answers
27 views

Understand the assumption of the ideal bright line in this paper

hope I ask my question on the right place. I am a student and my favorit subject is computer vision. I try to understand some apects of the paper "Three-dimensional multi-scale line filter for ...
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0answers
71 views

What is pulse train filter?

I have recently seen some code written in modelling tool like Simulink, ASCET which uses PT1 filter? Why do we use a pulse train filter? What is the difference between FIR, IIR, Chebyschev, ...
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3answers
27 views

Texture-like measures for quantifying density of data in binary images

Consider the following black-and-white image. It depicts a freehand sketch. I wish to characterize the "density" of sketch strokes. For e.g. the hair strokes are densely grouped together. So are ...
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1answer
36 views

Contour based blurring

Suppose I have an image of a cat and a binary mask image corresponding to cat's location as shown I would like to blur the image region surrounding the cat but as a function of distance from the ...
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3answers
214 views

difference between mean filter and order statistic filter

I am working on my paper about comparing between mean filter and ordering statistics filter, The mean filter is contraharmonic mean filter and the ordering statistic filter is alphatrimmed mean ...
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1answer
73 views

Discrete sinusoidal to state space

I'm looking to apply an optimal LQR filter to a discrete signal of the form $x[n]=A\sin[\omega_0n + \phi]+ v[n]$ The amplitude $A$ and the phase $\phi$ are unknown variables I want to estimate using ...
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0answers
78 views

MATLAB, recover a signal that has a cosinusoidal interference and that has been AM modulated

I have a signal which has been AM modulated but the channel also added a cosinusoidal interference A cos(2 * Pi * f0 * n * Tc + Phase), at the same ...
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1answer
81 views

How to calculate Gaussian kernel for a small pixel size?

How to calculate the values of Gaussian kernel? I think I understand the principle of it weighting the center pixel as the means, and those around it according to the $\sigma$ but what would each ...
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0answers
49 views

amplitude compensation after filtering and mixing audio

I am working on a mixer which lets me mix dry and wet signal in a user defined ratio. Wet signal is basically just the all pass filtered signal. The mixing takes place in frequency domain and so does ...
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1answer
38 views

How does kernel work in unsharp masking?

I applied the kernel below to the picture for unsharp masking k = [-1 -1 -1; -1 8 -1; -1 -1 -1] I got ! Then I changed 8 to 14. And I got How does kernel work ...
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1answer
143 views

low pass filter with minimal ringing

I am trying to filter out some square wave signal to within a limited band (1/4 or 1/8 of the original), I realized that there's a lot of ringing in the wave when I use my filter (elliptical), I also ...
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1answer
65 views

Matlab: is a highpass filter what I want, to obtain my required spectrogram? How do I design/apply this? (pic included)

The axes are wrong in the spectrogram. I have an audio wav file, and I know the sampling rate. this is read into the audioData variable. The audio is 1 channel. selected window length I believe (can't ...
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1answer
36 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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0answers
30 views

savizky-golay filtering

I have a signal sampled at 400 [Hz] and I would like to filter the signal at the lowest possible frequency , around 5 [Hz]. I studied this FIR filter, all I need to set is the polynomial order and ...
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2answers
184 views

filtering in frequency domain

I am performing decorrelation of two channels of audio using all pass filtering. The two all pass filters for two channels are of very high order (>1000 but with not all coefficients non zero). I have ...
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1answer
38 views

Notch filtering line noise outside of frequency band of interest

Practically speaking, if one is interested in a frequency band well-separated from the line noise (say, for example, the 10-20 Hz band, with 60 Hz line noise), would it be advisable to notch out this ...
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1answer
53 views

LPF - signal values unaffected at specific times

Is it possible to design an LPF that has an output identical to the input at specific points in time domain (the rest of the input waveform can get filtered/distorted)? Is there a general ...
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0answers
61 views

Fractional equalizer with non-integer oversampled signal as input

I would like to know how the output sequence from a fractionally spaced equalizer, with a non-integer oversampled input signal, is generated. For example, for $T=T_{sym}/2$, my actual code is ...
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0answers
19 views

Morphological gradient versus linear gradient

To obtain the gradient from an image, one can use a linear filter that for example is derrived from the derrivative of a gaussian. Then convolving the image with this linear filter gives you the ...
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2answers
167 views

Equalizing 1/f noise

I am recently acquiring data through ADC on signals ranging from 0.1 Hz to 50 KHz (Fs = 128 KHz). I noticed that apart from the white noise, I have something similar 1/f noise with a cutoff near 1 Hz. ...
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1answer
57 views

use scale space representation to filter one image

Currently I hope to use scale space representation to filter one image. Features in one image can be filtered using an Gaussian smooth filter with one optimal sigma. It means different features in one ...
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1answer
94 views

Filtering Passband Signals using Complex Baseband Filtering

So I'm given a pass band filter with specific transfer function $H_p(f)$, I want to implement this via baseband processing. I already know how to take the input signal $u(t)$ and process it such that ...
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0answers
80 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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2answers
163 views

Filtering Overlapping Frequencies in sound file

I have been given a sound file of a plane passing over a rain forest filled with birds. I am supposed to filter out the sound of the plane as it flies over. I've accomplished this with various types ...