# All Questions

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### Can I compute signal-to-noise ratio on a vector-valued or multi-channel signal?

I have a dataset that contains multiple channels recorded over time (think EEG or EMG), and I'm working on a computational model for this data. When I have a working version of the model, I'd like to ...
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### Applying an FIR filter in R not working as intended

Here's the working Matlab code first: ...
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### The use of wavelets in modelling a time series ( in feature extraction part)

I have been working on modelling a time series using wavelets for a long time. I am quite familiar with the wavelet theory and all...However, I have a big understanding issue and really appreciate it ...
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### The idea to resolve false edge problem?

I try to resolve false edge problem in image segmentation. Let see its defination in Figure. The false edge problem often occurs in inhomogeneity image, especially for medical image. I am finding the ...
35 views

### Simulate a simple multipath channel for OFDM Modulation test. MATLAB

Hi I need to simulate a simple multipath channel in matlab through which I can send my OFDM transmission signal, I want to test my OFDM receiver design. So far I have: ...
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### Canny non-max suppression intro

I have reach experience signal-processing, but haven't touched image processing since my happy university days... so: Working on a side project, I need to enhance ridges (continuous lines) in a 2D ...
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### TDE, OFDE and FDE equalizer simplest exmple in matlab

I want to implement the equalizer in matlab. I am just learning this. I want a good kick start code that can help me to learn it further. I searched a lot on Google but do not find a good reference ...
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### Feature extraction/reduction using DWT

For a given time series which is n timestamps in length, we can take Discrete Wavelet Transform (using 'Haar' wavelets), then we get (for an example, in Python) - ...
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### How to choose a FFT algorithm?

There are many algorithms that can calculate FFT. Even with Cooley–Tukey FFT algorithm, different radix can be used and the algorithms can divided into decimation in time and decimation in frequency. ...
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### Mathematical model of a large AR system for sparse system identification

I am new to the topic of system identification and looking for a large model of Autoregressive (AR). I am working on Sparse system identification http://tbayes.eecs.umich.edu/yilun/sparselms (example) ...
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### FFT for bearing fault analysis

Why is FFT a good method for detection of bearing faults? Why can't we do the analysis in time-domain?
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### Multilevel 2-D Wavelet Transform as a Matrix

I am trying to generate a single matrix $\Psi$ that will perform a multilevel 2-D wavelet decomposition. Such that for a 2-D image $X$, I can produce a coefficient "image" $\Theta$ as follows: ...
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### Image objects dispersion and diversity measures

I have images like below: I want to find some measures describing black spots dispersion and diversity. First measures I use are mass center off all black spots, mean area of spot, stdev of area ...
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### What type of correlation is this equation?

In a book [1], gives an equation (equation 5.31 in the book) for estimating frequency offset in OFDM systems proposed by Classen. the procedure is: first, two OFDM symbols, $y_l [n]$ and \$y_{l+D} ...
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### How does time shift correspond to phase change in a discrete signal?

I was watching this video where the presenter remarks: For a discrete signal, time shift corresponds to phase change in a discrete signal but not vice versa. I was trying to figure out how ...
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### 3D effects like HTC One Dimension plus

Its true that HTC one M8 uses dual camera to achieve the 3D Dimension plus effect, but can anybody tell what is it called, if its a series of image manipulation? Demonstrated here, Video
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### Missing some Matlab functions in Octave

I need following functions which is not in Octave : paddedsize(); dftuv(); I already installed this packages on Octave : ...
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### How to get spectrum of an image?

I have an image : img = imread('pic.jpg'); Now, How can I get spectrum of that image?
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### Why dont sin and phase shifted cosine overlap?

I plotted a sine wave(blue) and a 90 degrees phase shifted cosine wave (red) expecting them to overlap each other. ...
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### Correct image rotation/scale/moving change

I'm pretty new to Image Processing and am using MatLab. I have an problem were I take an image of light passing trough an set of optical fibers (bundled together) and one were I pass laser energy ...
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### Continuous time-domain electrical signal that only has a finite number of possible values

I have recently started learning DSP and the book that I am reading challenges the readers to find a: continuous time-domain electrical signal that only has a finite number of amplitude values ...
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### Measure of intermittency/continuousness of a signal

I have three signals (below) each having the same standard deviation, however, are clearly very different temporally. Is there some such metric that could be calculated for each of these signals to ...
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### inverse Fixed point number (number^-1)

Could someone please provide a method for inverting random fixed point numbers. I have as an input both positive and negative floating point numbers that should be converted into fixed point and be ...
33 views

### Trying to translate formula for blending mode

I am using OpenCV C++ for making the blending mode like in photoshop, I want to make overlay mode in it. I search its alternate in OpenCV in which I found this ...
18 views

### How to read an image in Scilab

In Matlab we use below function to read an image : var = imread('IMAGE‌‌ ‌PATH'); But, how to do same thing in Scilab ?
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### How vibrance method of photoshop work in opencv

Can somebody please explain how Photoshop vibrance function can use in opencv c++ ? so that I may reproduce the same effects in my application. Here is the vibrance ...
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### How is split step fft beam propagation method constructed numerically for spatio temporal evolution of short laser pulse?

For ultrashort laser pulses the propagation in space couples both transverse space and time domain to produce transverse space dependent pulse duration. A split step fft method propagates single ...
47 views

### Band Limited Impulse Train Synthesis

I'm currently working on a piece of DSP/Synthesis software and I have run into the issue of generating band limited waveforms. I have been doing some research to try and find a good solution but I ...
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### How to understand energy function in thin plate splines?

guys! I have carried out some experiments using matlab warp tools from here. But the results are not good, so I decide to read its original paper Principal Warps: Thin-Plate Splines and the ...
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### Finding Accurate BPM and Beat Time Values in Audio

I working on writing a program to get the BPM rate and the Beat Times in audio songs but I am having trouble trying to come up with reliable testing strategies for my design.What do I benchmark my BPM ...
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### PSD Estimation: Welch's method with median averaging

I would like to use median averaging when making a PSD estimate via Welch's method. I notice that this is available as an option in R welchPSD, but not in SciPy or Matlab (in which the default is mean ...
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### Image to Binary stream for OFDM with qpsk/qam modulation matlab

Im looking to covert a .png or .jpeg image into bitstream so that I can further use it as input bit stream for OFDM with QPSK/QAM modulation in Matlab. I would really appreciate the help on that. ...
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### Fast cross correlation with limited range

I am measuring the phase shift between two pseudorandom signals using correlation ifft(A.conjugate()*B) and picking out the maximum). That works very well, but takes a lot of time. I roughly know ...
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### Counting human movement of exercise using ROI or pre-set passing line with OpenCV

Hi all I'm new to this page hope you all can guide me. I'm currently doing my final year Degree in computing studies. The project I'm working on is a video of a webcam or computer webcam to have 2 ...
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### Looking to educate myself in dsp theory

I'm currently studying sound design, however over the past couple of years i started creating audio effects/instruments. I have also been programming in C++ for quite some years. I noticed my ...
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### Understanding frequency domain using Z-transform

My question might sound a bit confusing,because my professor asked it and I`m not really sure I got what he meant.Imagine we have converted a signal into complex frequency domain representation. What ...
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### Differences between matlab's 'impulse' and 'lsim' command; create impulse response

I've got following problem: assume you've this continous system 1st order: $$H(s) = \frac{1}{1+s}$$ s = tf('s'); sys = 1/(1+s); I'm going to discretize this ...
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### Resonant peak frequencies for phaser effect

I have a conventional phaser setup with allpass filters and feedback. I can calculate the peaks frequencies of the phaser when the allpass delays are set to 1 (then they work as simple one sample ...
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I'm going to simulate OFDM system and reighley channel in MATLAB. I create array of 128 symbols (for example) and then get IFFT, add CP. passing through AWGN channel in easy, but in Reighley there is ...
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### Estimate the type of wavelet transform in receiver side

Suppose that a signal is decomposed by using discrete wavelet transform (DWT) and transmitted. Is it possible for receiver to find which type of wavelet is applied in transmitter side ? I mean, if ...
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### Classifying images with standing\sitting people

I have images that contain two people. They can be divided into the next categories: Both people are standing. One person is standing, and one is sitting. Both are sitting. I want to classify each ...
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### Histogram as a feature in Make3d

I am reading the one of the publications of the Make3d project. the NIPS one. which uses a machine learning approach and MRF to estimate the depth from a single image. In this paper in part 3.2 the ...
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### How to calculate the local gradient of an image in MATLAB

I know that the gradient function is supported by matlab, but the local gradient is not, so how do you calculate it?
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### Cost matrix for syncing audio signals

Is it realistic to, in real time, calculate a cost matrix of two onset location vectors? e.g. process two output(system) audio buffers and get onset locations in vector. calculate cost matrix ...
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### What is mismatched noise?

Can anyone simply explain what mismatched noise is? And what is the noise that is not mismatched noise? Thank you!
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### Implementing the Naive Discrete Fourier Transform (Not FFT)

So, I am trying to implement the Discrete Fourier transform and its inverse for the purposes for gaining a better understanding of how it works. The two functions are inverses of each other. (modulo ...
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### Haar wavlet Transform in OpenCV

I am new to OpenCV. I am working on implementation of Haar wavelet transform of an image in OpenCV in C++. Please anyone suggest me how to implement?