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17 views

Fast Normalized Cross-Correlation for Stream-Data

I read some papers about fast normalized cross-correlation techniques. Most of them are used to identify a template in an original image. I was not able to find information about input-data in a ...
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1answer
44 views

Code generation for `sum` function in MATLAB

In cross correlation we use the below command to calculate the sum after elementary multiplication of the vectors. But when we try to convert this Matlab code to vhdl using HDL coder, this command is ...
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1answer
66 views

Python - Normalized cross-correlation to measure similarites in 2 images

I'm trying to measure per-pixel similarities in two images (same array shape and type) using Python. In many scientific papers (like this one), normalized cross-correlation is used. Here's an image ...
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0answers
43 views

Problem in hardware implementation of cross correlation without xcorr

Sorry for any thing silly! Matlab uses the built in function called 'xcorr' to find correlation of two signals.In VHDL xcorr is not defined then correlation can be written using for loop ...
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1answer
33 views

Calculating similarity between bit strings/signal

I have a project I'm working on where I'm trying to efficiently compare sequences of binary data to determine how similar they are. Basically, a sequence might look like this: 1001010010100011110... ...
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3answers
74 views

Estimate changing time lag between signals

Suppose I have two timeseries $x_1(t)$ and $x_2(t)$, shown in the image that I drew below. They look almost identical in general form, except some features are shifted slightly in time from one series ...
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1answer
42 views

Can anyone help with cross correlation error in Simulink?

I am sorry if I say any thing silly. I have a vector x below and trying to implement correlation with itself (lets say x2) in Simulink, but getting error. I am ...
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0answers
51 views

Why correlation coefficient template matching perfoms better than cross-correlation and square-differences method

I am using this template in OpenCv's match template function by converting all images to grayscale. Here are my result using sum of square differences,cross correlation and correlation ...
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2answers
116 views

Finding a signal inside a time series using matlab xcorr()

I would like to find the exact replica of signal A in time series B. I am working with the simple toy example below, in which A is located starting at the 4th position in B. I thought that using ...
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1answer
58 views

Applying a window to input signal

I am sorry if I say any thing silly .Please forgive me.I want to apply a window to input signals.I have two signals each of which contains zeros (462 samples) and non zeros data (38 samples).I want my ...
3
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1answer
212 views

Auto Correlation vs Cross Correlation vs Convolution and their applications

I know from wikipedia that auto correlation in done on the same signal while cross correlation is done on different signals.But what does this actually imply in terms of application.I can always apply ...
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1answer
44 views

find cross correlation lag by optimization

I have data from many closely located sensors (geophones). These are often contaminated with coherent noise which I need to remove. Some of the most effective de-noising methodologies work if the ...
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0answers
18 views

Null Steering using MVDR for a 4 antenna array

I am trying to get a null in the interference direction using MVDR. MVDR requires a matrix inversion. When i am implementing it, i am getting two nulls, one in the desired direction and one more in ...
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1answer
54 views

Bartlett's and Welch's Method for PSD

Lets say. I have an image of 100 samples, and I want to find the presence of smaller image of 24 sample using cross-correlation in the fourier domain. I use Bartlett's and Welch's method for PSD, ...
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1answer
41 views

Mismatched offset when computing cross-correlation using FFT

In MATLAB if I compute the cross-correlation of 2 arbitrary signals using the xcorr function I get exactly the answer I expect. If I then calculate the cross-correlation using element-wise fft ...
0
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1answer
41 views

How to compare the syllable extracted from the audio

I need to recognize just one bird. I am trying to compare the syllables extracted from the sound samples. As a result of the spectrogram function, the power spectral density is taken from the sound. ...
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1answer
38 views

Quantification of the extent of periodicity in a time series using fractal analyses

I need metrics to quantify and compare the extent of periodicity between any two given time series, considering the time series were "almost periodic". By "almost periodic" I mean: if I were to take ...
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2answers
95 views

Audio template matching - power correlation?

I'm looking at some code that matches audio templates in a longer audio file. The calculation correlates the power spectra of the template and audio file, maximizing over the possible alignments. This ...
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0answers
26 views

Effects of simplifying normalized cross correlation equation

The normalized cross-correlation equation for images looks like this (from here): \begin{equation} \sigma(u, v)=\frac{\sum_{x,y}(f(x, y)-\bar{f}_{u,v})(t(x-u, y-v) - \bar{t})}{\sqrt{\sum_{x,y}(f(x, ...
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1answer
81 views

Scaling Data before Fourier transform

I am doing an experiment, where I am trying to get the same results from correlating two matrices in the fourier domain and then scaling the data by some constant. Method_1: Do FFT, Correlate the ...
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2answers
91 views

how to match 2 signals that have same information, though shifted and scaled

I have 2 signals S1 and S2 that contain the same information, but S2 is shifted and scaled compared to S1 by an unknown amount (but small; eg shift would be of the order of 1-10 samples). What is the ...
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0answers
22 views

Getting image intersection area perentage

i have two flying robot. And they are flying at same height (nearly) and they are looking same direction and pose. Both of them have same camera and the cameras looking to floor. When the robots are ...
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0answers
53 views

Normalized Cross Correlation in Frequency Domain Windowing for Object Tracking

I'm implementing a normalized cross correlation algorithm in frequency domain on a DSP for object tracking. I have a search window and a reference window. Both windows are zero padded to accommodate ...
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1answer
111 views

Cross-Correlation to find the similartity of songs

I have been working on a problem where I am given two songs which are of the same category but there is a time difference between them. Eg. one song starts at x sec and other song starts at y sec. So ...
2
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1answer
58 views

Is jointly wss (wide sense stationary) a transitive relation?

I've been try to either prove or find a counter-example to the idea of jointly-wss being transitive. In other words: does ($x$ and $y$ are jointly wss) $\wedge$ ($y$ and $z$ are jointly wss) imply ...
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1answer
632 views

Computing cross-correlation of two images using OpenCV

I have a program that uses OpenCV to compute either the convolution or cross-correlation of an image with a specified kernel. I compute cross-correlation by setting the conjB flag to true when calling ...
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1answer
158 views

Baseline correlation for template matching

In normal cross-correlation or convolution between a signal and a template(say a small portion of the signal) the template is moved along length of the signal without changing the amplitude offset of ...
0
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1answer
119 views

PSS convertion from Frequency to time domain

Hi I have a question regarding primary sync signal in LTE. It is generated in frequency domain and its length is 63. How to convert this signals frim frequency to time domain. Should I use IFFT? what ...
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0answers
16 views

Computing distance between two sattalite images

I want to make distance estimation from matching two sattalite images. Images taken from same height and same orientation (top middle shows north). Training images taken from google map and target ...
0
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1answer
34 views

how to find the dependence between two sparse signals?

Hi and thank you for your help. I am new to signal processing and would really appreciate your help. happy to provide more context/details. In my research, I have a system that has many sensors ...
0
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1answer
50 views

Is there any reason that cross correlation would perform well or poorly on sparse binary arrays?

I am using matlab xcorr to correlate simulated photon count data that has some Gaussian random noise set on top of it and it is working fine when the average value ...
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3answers
511 views

Cross correlation with short or non periodic signals?

I am a total newbe to signal processing and i have a problem which may be quite trivial to most of you guys. I want to align two short sensor signals (speaking of max. 1000 samples recorded with ...
0
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0answers
261 views

Compare two voices and outline their similarity

I am trying to develop an application which records the voice of someone through a microphone. I will have a preset recorded voices for the same words. I then need to compare the real time recorded ...
0
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0answers
19 views

Deconvolving two vectors produces a single number (not a vector)

I am trying to deconvolve the auto-correlation of my source wavelet (Ricker wavelet) from my receivers responses. Now if I deconvolve the source wavelet out of the response I get a vector back and the ...
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1answer
163 views

Efficient calculation of correlation function every $N^{\rm th}$ point

I would like to calculate a long correlation function of length say, 1e6 points. I have a prior knowledge that the correlation peak will be in point k*1000. Is there an efficient way to apply this ...
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0answers
75 views

“Circular shift - invariant” distance

Couldn't decide whether the question belongs on Mathematics or here, but I guess I'll ask it here. I've got a discrete - valued function defined on a finite segment of a line that looks like this: ...
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0answers
50 views

filter out an expected but not regular signal

I am stuck with a case where I need to get rid of a portion of sinusoidal signal that suddenly appears in my main signal (sine wave). my total signal will look like: $ s(n) = \begin{cases} ...
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1answer
140 views

Least squares and auto and cross correlation

I am trying to understand why auto and cross correlation helps find the best fit line in least squares. I have an equation as stated here: $Ax=b$ -- I have not exact solution, so I use the least ...
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2answers
67 views

Validate correlation of data

I have data from two samples of a biological process. The data consists of oscillations with noise in them. The noise is also relevant as it is characteristic of this data. I want to show that both ...
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2answers
165 views

Cross correlation peak value

I would like to measure the time delay between two signals. By applying the cross correlation I get the time delay or number of samples by the location of the cross correlation peak, however I am ...
0
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1answer
60 views

Auto/cross correlation of a cosine in the context of an adaptive beamformer

I am currently reading chapter 13 of 'Adaptive Signal Processing' by Widrow and Stearns, so if anyone happens to have a copy of the book to hand it could be helpful. I am reading the chapter on ...
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1answer
260 views

Efficient Marker Detection for Images

I need to detect a known number of simple markers (chessboard patterns) in a color image efficiently. I implemented normalized cross correlation (NCC) as a pixel shader via WebGL since I need this to ...
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0answers
676 views

Why Normalized Cross Correlation Score of different templates is high?

I am using OpenCv's built in template matching function to search for an object in image. I am using Normalized Cross Correlation Method.The function is returning a value which I think indication of ...
0
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2answers
99 views

“Perfect waveform” for cross-correlations?

I am well versed in cross-correlations, as my masters thesis heavily relied on them for music classification and beat detection. So this question focuses more on the signals that I am running an ...
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2answers
224 views

range and motion in received signals by radar

I've got two signals which are consecutive received signals by a radar system. the signals values are complex (in form x+iy). I have generated a trasmitted signal using the info available. Now, I ...
3
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2answers
173 views

Map time difference between two similar videos

Question: Is there any software, source-code, or well documented and easily implementable research (I am not afraid for a little bit of Python) to do the following: Take two similar videos from ...
0
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1answer
276 views

Cross correlation vs FFT for finding phase between 2 signals

I have been struggling with this issue for months now, trying to understand which one to pick: FFT or cross correlation. I am given a sine wave (with phase, amplitude, frequency and time vector ...
3
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4answers
311 views

“cascaded” cross-correlation

so, first let's do this for the circular correlation case (it might be easier). let's say we have three real and periodic functions or signals $x(t)$, $y(t)$, $z(t)$ all with period $2 \pi$: $$ ...
0
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1answer
317 views

Solution to Cross-correlation problem of 2 audio signals

There are 2 audio signals, X & Y. X is of 15 second duration. The duration of Y is not given. Y is a part of signal X (ie a small part of audio X is extracted & made into audio Y) I have to ...
0
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1answer
40 views

Avoid saturated pixels in cross-correlation computation

I am doing template maching using Normalized Cross-Correlation for measuring similarity between template and image. However, some images from my dataset contain saturated pixels (overshoot) which ...