In signal processing, a filter is a device or process that transforms a signal by selectively choosing specific frequencies and leaving others with appropriate gain or as it is.

learn more… | top users | synonyms (1)

1
vote
1answer
27 views

the rate of noise presented in images

I suppose that an image is affected by a multiplicative noise (or additive noise and etc.). I want to quantify and measure the rate of noise (for exemple 1%, 2%, ...,25%) present in an image. I used ...
0
votes
0answers
12 views

Detecting discontinuities in derivatives in images

Considering an grey-scale image as a function z=f(x,y). (Specifically, I'm interested in f=h∗h∗...∗h, where h is the indicator function of a regular hexagon.) I am interested in finding places where f ...
0
votes
0answers
17 views

Memory and bookkeeping for realtime window-overlap-add (WOLA)?

Given a realtime embedded system with input samples x(n) coming from an ADC, what is the pipeline to output y(n) if ...
-1
votes
0answers
47 views

Real world dsp implementations examples?

Well,this may be basic, but i find you as the best option to answer this. I am electrical engineer and i have taken dsp courses. There is some algorithm that i am trying to implement on audio signal ...
1
vote
2answers
60 views

Creating a flat spectrum filterbank

I'm trying to create a filterbank whose frequency response is generally flat when summed in parallel. Are there any tips to choosing center frequencies and bandwidths for a filterbank of overlapping ...
0
votes
1answer
41 views

FIR filter design for response inside unit circle

I would like to design an FIR filter such that its Z-transform has a certain profile in certain regions. For example, if I'd like to have an FIR filter that nulls the decaying exponential ...
1
vote
2answers
70 views

Complex low pass filters

I am searching for documentation on the behaviour of complex low pass filters, and their application in telecommunications. Thank you
0
votes
0answers
23 views

Building a distributed low-pass filter with cutoff frequency of $1$hz but the highest frequency of $10^{6}$hz

How does one build a distributed low-pass filter with cutoff frequency of $1$hz and highest frequency of $10^{6}$hz (or arbitrarily high)? In case of lumped circuits, this is easy to do, but in case ...
0
votes
0answers
22 views

distributed low-pass filter frequency range

Suppose that signal's frequency ranges from 0 to some very high frequencies. One builds a low-pass filter which needs to be based on distributed element analysis because lumped-element analysis is ...
0
votes
1answer
20 views

If I build a low pass gaussian filter in the frequency domain should I also normalize it with the sum of the filter coefficients?

I saw two examples of applying a Gaussian low pass filter to a Matlab image: one- when the filter was built in the space domain and was normalized with the sum of the filter coefficients, and another- ...
2
votes
2answers
67 views

DSP Hardware for Detecting an Audio “Click”

I am working on isolating a specific audio click in a factory type setting. After my initial analysis I determined that a 2-pole High Pass Filter set between 500 and 800Hz would work best for me. The ...
1
vote
0answers
17 views

Multirate filtering attenuates frequencies at overlap

I am trying to build a filter with different frequency bands in Matlab. I would like the filter to be as invisible as possible, but after the filtering, a great amount of frequencies are being ...
0
votes
0answers
41 views

Audio block-processing discontinuities

I have an algorithm that looks at an audio frame, calculates a threshold in db-rms, and decides to filter the frame whether or not the threshold is crossed. However, filtering each block is producing ...
0
votes
2answers
56 views

Is cutting EQ scientifically different than boosting EQ?

This is a fairly standard belief in the audio production scene that cutting EQ is somehow "cleaner" than boosting EQ. You hear arguments like there being different phase characteristics or whatever. ...
4
votes
1answer
78 views

Are noncausal filters ever used in practice?

Basically what it says in the title; I have just started reading about these things and find noncausal filters pretty interesting in concept, but also they do not seem like they would have any ...
0
votes
0answers
19 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 ...
0
votes
0answers
6 views

The interpolation formula for building a steerable 3D filter of a second-order Gaussian

I am trying to write the Matlab code for a steerable 3D function, but cannot find anywhere the interpolation formula between the spherical harmonics. I researched on the internet, but really didn't ...
2
votes
2answers
63 views

What is the definition of a “complementary filter”?

I'm writing my MSE thesis report on an inertial navigation problem I've been working on. In my work, I use a complementary filter to track the orientation of a device. Now, since my fellow students ...
0
votes
1answer
51 views

Vinyl Crackling Effect

I want to know how can I achieve this effect: https://www.youtube.com/watch?v=DQg9M_47c3A Do I need to use a filter? And what can I use for the crackling, poping effect? Thanks in advance!
0
votes
0answers
9 views

What I am doing wrong when applying constrast sensivity function?

Physics explanation I am filtering an optotype image in order to simulate how a human eye would see it. I am not taking into account aberrations but only diffraction. The problem is that my ...
1
vote
3answers
100 views

detrending in real time

I have a certain signal that has a linear trend that should be removed: The problem is that the signal needs to be processed in real time(sampling rate is 20Hz). If I only apply the detrending per ...
0
votes
1answer
90 views

Phase locking value / phase synchronization

I have pairs of EEG signals filtered to give me just alpha bands. For a machine learning problem I have found that calculating the phase locking value between the alpha signals of these 2 channels ...
0
votes
2answers
36 views

EEG Power at specific time points

I'm in the process of building features for an EEG machine learning problem and have been doing some reading about what features may be useful. Turns out, that alpha band (8-12Hz) power can make a ...
1
vote
2answers
42 views

Signal power without FFT

I have an EEG signal thats about 1second long, sampling frequency of 256Hz, measured in microvolts, and I want to calculate the power of a specific frequency band (8-12Hz) I believe the correct way ...
2
votes
1answer
274 views

C implementation of LP filter

I have the following code, which I am told is a low-pass Butterworth filter. How do I derive the frequency response and phase for this? I only have experience in analog electronics and so cannot ...
0
votes
1answer
24 views

How to apply a 1D filter (CSF) to an image?

I am facing the following problem: I have an image and a contrast sentivity function (CSF). The CSF is a function defined in the frequency domain and it is just a band-pass filter. The problem is that ...
0
votes
1answer
25 views

Removing DC offset and ensuring zero-sum for 2D filter

I'm working on project where I'm using Independent Components Analysis (ICA) on NxN patches from images to separate components in an image signal. Each column of the resulting MxN^2 unmixing matrix is ...
0
votes
0answers
21 views

What's the optimal filter size for a 2D Gabor filter

I started to experiment with Gabor filters to extract various image features from usual camera snapshots (that's the image domain: everyday snapshots with a very diverse range of subjects). ...
0
votes
0answers
47 views

Computing error between filtered and noisy time series signal

I have a live signal that needs filtering, and I'm trying to compare a Kalman filter with a simple exponential filter. For this I generated an artificial ground truth signal, add some noise and filter ...
0
votes
2answers
68 views

Forward and backward filtering

I have an input sequence $x(n)$ and impulse sequence \begin{equation} h(n) = \begin{cases} 0 & \quad \text{when } n = 0 \\ .239052 & \quad \text{when } n = 1 \\1.3357\exp(-0.650286n) & ...
0
votes
1answer
64 views

Python bandpass filter - singular matrix error

I've been trying to design a bandpass filter using scipy but I keep getting a LinAlg Singular Matrix error. I read that a singular matrix is one that is not invertable, but I'm not sure how that error ...
1
vote
2answers
154 views

Check if a filter is IIR or FIR

I have the following equation: $$H(z) = \frac{z^3+5z^2+3z+1}{10z^3}$$ I want to find out whether if its IIR or FIR. Here is the steps I have gone so far: $$H(z) = ...
1
vote
2answers
51 views

applying single pole filter to simple signal

How to apply single pole filter to simple signal fs = 500; ts = 1/fs; t = 0:ts:1-ts; fc = 50; S = cos(2*pi*fc*t);
0
votes
0answers
19 views

Correlation of an image in the Fourier Domain

I have been reading up on correlation in the frequency domain, and I just had two questions which I could not find in the book I was reading nor online: [1] So correlation is the same as a normalized ...
0
votes
2answers
114 views

FIR filters always linear?

Are Finite Impulse Response filters always linear? I looked at https://en.wikipedia.org/wiki/Nonlinear_filter and its says that if a filter does not obey linearity, it is non-linear filter. Thats ...
0
votes
0answers
55 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 ...
2
votes
2answers
48 views

Advantage of using FIR Polyphase Decimator over just computing FIR output every D samples

Let's say you want to implement an FIR filter $h[k]$ with $L$ taps and downsample the output: $v[k] = x[k] * h[k]$ $y[m] = v[kD]$ The "naive" way would be to compute all the samples of $v[k]$, then ...
3
votes
1answer
96 views

How to test digital filters?

First the question(s): How should I write unit tests for a digital filter (band-pass/band-stop) in software? What should I be testing? Is there any sort of canonical test suite for filtering? ...
0
votes
0answers
5 views

How can you test Gamma in ISP for test?

In CMOS image sensor, there are gamma processing block in the so many ISP chains. Is there any one know how to test the gamma block only whether working good or something wrong? How can you test ? Is ...
0
votes
1answer
55 views

Estimating an image filter from examples

I am sure this question must be fairly easy and could have been answered on this site but perhaps I am not finding the right keywords to search for it. I would like to know what are the common ...
1
vote
1answer
68 views

Computation Costs of Filters

Is there any general knowledge regarding the costs of computation time (computation complexity) of filters? Like what types are "generally" less/more costly than others.
0
votes
0answers
39 views

Filtering with filters without even or odd symmetry in the fourier domain

I am doing a project where I have to use the fourier domain for convolution. I have been reading Digital Image processing by Rafael Gonzalez but I unsure about one thing, and I could not find anything ...
2
votes
3answers
96 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 ...
1
vote
1answer
48 views

Lag in financial trading vs Group Delay in signal processing

I'm a newbie to Signal Processing - and so I'm providing a "background" and a "question" section separately. Background: Suppose I have a linear filter (w.r.t. given as $\theta_{t+1} = \theta_t ...
0
votes
0answers
20 views

Calculating poles/zeros from 4+ order transfer function

I need to calculate the poles and zeros from minimum 4th order (max ~20) filter coefficients. I have limitations that prohibit the companion matrix/eigen decomposition method used by roots() in ...
0
votes
0answers
28 views

Reversible QIM For watermarking

I have read your paper with title "Nested Quantization IndexModulation for Reversible Watermarking and Its Application to Healthcare Information Management Systems". enter link description here ...
0
votes
1answer
74 views

What are the alternatives to FFT for computing high-resolution tone power levels?

I have a system where there's a transceiver which transmits tones on specific frequencies (about 260kHz) and a receiver which is supposed to recognize those tones. The transmitted tones are of low ...
0
votes
2answers
71 views

How to generate realistic echo to sounds?

I guess the most straightforward way of adding an artificial echo to a sound signal is to add its time-delayed version to the original signal. However, I am not sure how realistic that would sound ...
1
vote
0answers
46 views

How to filter signals with non-uniform sampling rate?

I have a digital signal that was made from analog one by staggering sampling rate: $\tau_i = \begin{cases}\tau_{even}& \text{if } i = 2n\\ \tau_{odd} & \text{if } i = 2n+1\end{cases}$ And I ...
0
votes
0answers
19 views

Use the line function commend matlab of PDE toolbox in image processing

I want to use the line new command of PDE toolbox as Matlab R2015a to restore a noisy image with gaussian noise. The PDE is : \begin{eqnarray} \nabla.(\frac{ \nabla u}{\sqrt{1+|\nabla u|^2}}) ...