# Questions tagged [reconstruction]

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116 views

### How to choose an interpolation method for seismic ground motion signals

I am working with seismic ground motion records from the PEER database. They are acceleration measurements that are band limited to 50 Hz and sampled at 200 Hz. I use these records to drive an ...
138 views

### image reconstruction using a set of kernels

I try to be brief. For what I understood Convolutional Neural Network CNN for style-transfer extract/learn the main features of source Image. I think these features basically are Kernels (of different ...
755 views

### Two-View 3D reconstruction using the sparse Levenberg–Marquardt algorithm

I have trouble implementing the Levenberg-Marguardt algorithm as described in the book Multi View Geometry in Computer Vision. To be more specific I have trouble calculating the partial derivatives ...
33 views

### How to sample $f:=f_{1}\cdot f_{2}\cdot…\cdot f_{K}$?

Let $f_{k}$ be $\sigma_{k}$-bandlimited, $k=1,2,...,K$ and define $f:=f_{1}\cdot f_{2}\cdot...\cdot f_{K}$; then how should I choose $T>0$ such that we can recover $f$ from samples $f(nT)$? ...
101 views

### What algorithms can automatically determine a 3D scene from one or a few 2D images?

For a project I'm doing, I'm trying to model a scene based on a phone camera's video input, and then insert arrows into it that indicate direction in three dimensions. I've looked around, and this ...
519 views

I have trouble accepting the merits of zero padding in the frequency domain to give more points in FFT. Wonder if anyone else has similar thoughts. The mathematical 'proof'for the validity of zero ...
475 views

### Signal values we will 'miss' between sampling instances during sampling of band limited signals

According to the Nyquist–Shannon sampling theorem, any continuous time signal with a bandwidth $B$ smaller than Nyquist frequency $f_N=f_s/2$ (with $f_s$ the sampling frequency), which is sampled at ...
108 views

### Simulating noise in computed tomography reconstruction

In the research of the computed tomography (CT) reconstruction, one needs to simulate the noise during CT projection and capturing. Then, my questions are: How about the proper noise type? How to ...
819 views

### Computing sine phase and amplitude

I need to compute the DC offset, amplitude, and phase of a sine wave and I would like some help validating that my current technique is correct and get some tips to improve my technique. I am a DSP ...
45 views

### Question about MRI signal construction

As I understand it, in MRI, a line in k-space is usually acquired while the readout gradient is applied. So during the application of this gradient the protons spin at different frequencies along the ...
504 views

### MRI reconstruction using windowing based apodization

I am trying to apply windowing to do MRI reconstruction. I have a 256 point one dimensional k-space samples which look as follows: Here, the real part(green) is flat around 0 and the blue curve is ...
140 views

### Method of reconstructing a band-limited signal from discrete samples

I understand current cell phones use digital communications. Given that this industry brings in billions of dollars each year, there is much incentive to get the best performance possible. So what ...
678 views

182 views

### Complex numbers in $\tt ifft$ 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 ...
975 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 ...
884 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 ...
4k 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 ...
1k 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 ...
172 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 ...
964 views

### What Is the MATLAB imreconstruct() Useful For?

Could some one tell reasons to use the MATLAB imreconstruct function when processing images? I already have studied the topic and what the function actually does to ...
229 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 ...
132 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 ...
135 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 by ...
2k 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 ...
332 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. ...
584 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 ...
168 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. ...
134 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 ...
76 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 ...
266 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 ...
9k 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 ...
913 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 ...
245 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 ...
2k 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 ...
7k 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 ...
242 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 ...
I am implementing reconstruction of image from gradient domain. This requires solving the following partial differential equation (a Poisson equation) on a 2D grid: $$\nabla^{2}I=\mathbb{div} G$$ \$\...