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1answer
36 views

Upsampling and zero order hold

Maybe to someone this question may seem quite easy but I have a problem grasping it. Namely, assume that we have two systems A and B with sampling rates $f_A$ and $f_B$ where $f_A>f_B$ and ...
0
votes
1answer
12 views

Reconstruction of voice from distorted recordings

I would like to know how much of the sound of my voice getting through various types of walls can be reconstructed with easily obtainable software and algorithms. My plan is to place a microphone on ...
1
vote
1answer
55 views

How can a signal have two maximum frequency components?

$x(t)$ can be exactly reconstructed from its samples at $\omega_s = 10 \textrm{ rad/sec}$. My conclusion is that the maximum frequency component in $x(t)$ is $5\textrm{ rad/sec}$. But I'm being told ...
4
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1answer
71 views

Random sampling vs uniform sampling

In this paper of Lustig, he speaks about a something which appears unintuitive: sampling at random may exhibit better performance than sampling uniformly. I tried to understand this starting from page ...
0
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0answers
23 views

Simple sample and reconstruction code - MATLAB

I am trying to go from theory to code. I take x (let say 16KHz is continuous time) then I sample it in 2Khz So I do ...
0
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0answers
45 views

STFT on audio signal

I am trying to implement a STFT on audio signal as an exercise, and in order to do real-time filtering if I can get the "sound->STFT->inverseSTFT->reconstructed sound" chain to work. What I do for ...
1
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0answers
18 views

How to reconstruct 2D flat image from a series of pictures of a tube

I have pictures of an oesophagus (ie a tube) taken under standard white light looking down the tube. I have about 10 images taken over 20cm in series. The image looks forward down into the tube and ...
2
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2answers
55 views

image type after an ifft reconstruction

I reconstruct images from MRI k-space using ifft and root-sum-of-squares method. ...
0
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0answers
33 views

Recover original image values in unfiltered backprojection

When performing unfiltered back-projection, is there a way to have the reconstructed image values match the values from the original image? For example, if one executes the following example code from ...
1
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0answers
75 views

How to reduce reconstruction noise from a filtered back-projection reconstruction of a circularly symmetric image?

I need to perform tomographic reconstruction of an axially symmetric object. Because of the axial symmetry only one projection of the object (one angle) was taken. I implemented the filtered ...
0
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0answers
46 views

Fourier of a function in Matlab

I have a function describing a fourier transform of type : \begin{equation} \mathcal{F}(C(t)) = 1.42 \mathcal{F}\left( \exp^{-1.192t} u(t)\right) - 12.44 \mathcal{F}\left(\exp^{-1.192t} u(t)\right) ...
0
votes
2answers
101 views

Sample and reconstruct a real exponential (just one period)

I have a function with an equation: $$C = 1.6925\left( e^{-0.136t}-e^{-1.192t}\right) $$ Where $C$ is real and $t$ represents time in hours. Beneath is the representation of my function. I am ...
0
votes
2answers
116 views

Reconstruction of bandpass filtered signal from decimated version of itself

I know how to up-sample a discrete, real signal (by an integer factor n) that is band-limited to frequencies between $f_1 = 0 \mathrm{Hz}$ and and $f_2$: Just insert $n-1$ zeros between every original ...
0
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2answers
92 views

Ideal reconstruction after down sampling

The signal $x_a(t) = \cos(2\pi450t)$ is sampled. F = 450 Fs = 1000 Hz f = F/Fs = 450/1000 // Sampling theorem is fulfilled x(n) = cos(2*pi*(450/1000)) The ...
-1
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1answer
39 views

linear interpolator replacement for the sinc function

How to find an optimum linear interpolator replacement for the ideal sinc function? The reason is for the hardware implementation ease. For example when I use sinc interpolation: ...
0
votes
1answer
170 views

optimization of Image Reconstruction Algorithm using Genetic Algorithm in Matlab

I'm trying to optimize an image reconstruction algorithm using genetic algorithm.I took initial population size as 10.I have an input image an 10 reconstructed image.fitness function is the difference ...
0
votes
2answers
35 views

What is done to minimize distortion due to the hold operation?

A hold operation can be modeled using a step function over one sampling period i.e. $R(t) = 1/T * (h(t) - h(t-T))$, $h(t)$ the step function In frequency domain this is equivalent to $R(jw) = ...
0
votes
1answer
139 views

Complex numbers in ifft of an MMSE amplitude estimator

I am trying to reconstruct a signal from a noisy speech using an MMSE algorithm proposed long time ago by Ephraim and Malah (1984). After going through the algorithm, I got a matrix A which represents ...
2
votes
2answers
422 views

Is magnitude information enough to reconstruct an audio signal

I have used an MMSE STSA estimator to obtain the magnitude of an audio signal. The original signal is combined with white noise and I used an algorithm given in an old research paper by Ephraim and ...
0
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0answers
128 views

What are the frequency components of a sampled signal after low-pass filtering?

A continuous signal $x_a(t)$ is a linear combination of sinusoids of frequency 250 Hz, 450 Hz, 1 kHz, 2.75 kHz and 4.05 kHz. The signal $x_a(t)$ is sampled at $f_s=$1.5 kHz, and the resulting digital ...
0
votes
1answer
917 views

Reconstructing time domain signal with Hanning window

I am currently working on a frequency domain real-time application on a digital signal processor. Currently for one time frame of my algorithm I read in time domain data into a buffer, perform a ...
1
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3answers
128 views

Are reconstruction filter always needed?

in mixed (digital and analogue application) where you have to convert a signal from continuous to digital time domain and then back again to continuous time an anti-aliasing LPF is needed and in ...
1
vote
1answer
110 views

Beyond cross-eyed 3D (VR application)

Making static 3D image is very simple - we just take image pair with something like this: then we can see 3D image by putting the left and right eye image side by side and crossing eyes or ...
0
votes
1answer
97 views

Ideal Reconstruction of Upsampled Signal

Problem: The signal $cos(2\pi14100t)$ is sampled at $F_s = 400 Hz$. It is then upsampled with a factor 3 and then reconstructed ideally with a new frequency $F = 500 Hz$. I now want to find the new ...
1
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0answers
67 views

Calculate the intersample peak of a periodic sequence?

Similar to Calculating the PDF of a waveform from its samples, but for periodic sampled signals, and I just want the peak. Is there a way to calculate the highest inter-sample peak of the ...
1
vote
2answers
128 views

Computing shifted signal without first reconstructing

Looking for a solution to the following problem: A signal $x(t)$ is band limited to $B$ Hz, and sampled above the Nyquist rate, with corresponding $f_s = 1/T$. If the sampled signal is given ...
0
votes
1answer
826 views

reconstruction of time series in SSA

i am trying to reconstruct time series from SSA ,because according to this link http://en.wikipedia.org/wiki/Singular_spectrum_analysis there is procedure ...
0
votes
1answer
136 views

Incoherence: Compressed Sensing (CS) vs Matrix Completion (MC)

I am seeking a clarification of the concept of Incoherence within the MC framework. Specifically, 1) the literature mentions the application of a "strong incoherence" given a set of assumptions. ...
2
votes
1answer
351 views

Reconstruct DWT for each cD1,cD2,cD3 and cA3 signals

This question must be basic for this forum, but I'm only start working with DWT recently, and I was working with CWT before. I ...
5
votes
0answers
125 views

Stochastic process inference from partial observations

Consider a set $U$. My signal is a piece-wise constant "function" $Sig: t \mapsto s$, i.e. the signal at time $t$ equals to some subset $s \subset U$. One can see $Sig(t)$ as a stochastic process. ...
2
votes
0answers
70 views

Upsampling Methods for Computed-Tomography

I have two sets of data of given Field of view, one of them only covers a subset of the FOV of the other. I therefore want to upsample the one with the larger FOV to combine it with the other one. So ...
0
votes
0answers
54 views

Reconstructing a partially deleted image through wavelets

I am trying to form an approximation of the wavelet transform from a partially sampled image. Reconstruction in the 1D case is easy. We have $w = h x$, with $w$ as the wavelet coefficients, $h$ as ...
3
votes
1answer
206 views

Explanation of LidarBoost Algorithm?

I am trying to understand the LidarBoost algorithm as explained in this paper (PDF warning). I don't understand how they take the original depth-images $Y_k$ and transform them into the up-sampled ...
1
vote
1answer
4k views

Sampled signal reconstruction using matlab

I have a wav file recorded from my smartphone's mic, and I want to reconstruct the sampled signal and plot the reconstructed signal. After some research and search, I was able to get the following ...
1
vote
2answers
584 views

Radon Transform reducing the number of parallel beams (MATLAB)

I am trying to understand different filters' and other things' effects on Radon Transform by using MATLAB. First I upload an image, then take its Radon transform with radon function and then ...
7
votes
1answer
143 views

Remove noise on edge (compression deffects)

I have the images of cartoons, that were compressed. The example: They have such noise, that is not easy to delete. Even though the pixels are on the gray background, the noise pixels can be of ...
2
votes
1answer
970 views

Texture mapping on a 3D face from 2D face image

I have 3D points (xyz) of a face image and I have 2D face image of the same person. The 3D points of the face are such that If I project the points to 2D plane, it matches with the 2D face image. I ...
0
votes
2answers
3k views

what is the effect of variation of duty cycle of sampling frequency on a reconstructed signal

I have been asked to study an experiment which says "what is the effect of variation of duty cycle of sampling frequency on a reconstructed signal" I am not an electronics/electrical engineer I am ...
0
votes
2answers
131 views

What is the procedure to obtain a 3D face dataset? Can anyone suggest a good 3D face dataset?

Project Description: Input: Frontal Face Image Expression Angle Size Details: I have to convert the input frontal face image into 3D face and simulate the ...
4
votes
3answers
924 views

Gradient Domain Reconstruction - Scaling Problem

I am implementing reconstruction of image from gradient domain. This requires solving the following partial differential equation (a Poisson equation) on a 2D grid: $$\nabla^{2}I=\mathbb{div} G$$ ...