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# Questions tagged [reconstruction]

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47 views

### A Different Reconstruction Operation

I want to understand what is happening in below operation: Here, x(nT) is sampled signal (say oversampled) and h(t) is its ideal reconstruction filter. As highlighted in the expression, amount of ...
385 views

### Signal Resampling by a non integer factor with convolution

to start I am a newbie in signal processing, I just started a month ago so please be as detailed as possible. From what I understood to resample a signal by a non integer factor you can do an ...
11k views

### Discrete Wavelet Transform - Visualizing Relation between Decomposed Detail Coefficients and Signal

I'm trying to directly visualize the relation between discrete wavelet transform (DWT) detail coefficients and the original signal/its reconstruction. The goal is to show their relation in an ...
27 views

### What is the best way to separate data using compressive sensing?

In the book Compressed Sensing by Kutyniok et al, the author talks about data separation using sparse representation. In summary, if we have a signal vector $x = x_1 + x_2$ Then, it would be ...
122 views

### How can you 'perfectly' reconstruct phase for transients in a modified audio absolute spectrogram?

I am currently working on the absolute spectrogram of an input audio signal. I am using non-negative matrix factorization to separate out the rhythmic components (bass drum, snare drum and hi-hat) of ...
11 views

### How to get NMF sparse component factors

In the NMF framework, whenever I want to get a sparse component, I set the rank to 1 (lowest possible) and get the W and H matrices of the low-rank component by doing a multiplication of the resulting ...
827 views

### reconstruction filter - How does it actually work?

I'm trying to form my own understanding on the religious war around using 192kHz as a sampling rate for playback (the Internet seems to have a wealth of material on both sides). I'm struggling to ...
29 views

### Recreating an image from random samples?

Assume that I have samples from an image, but the samples aren't on a grid, but instead there are multiple lowres versions of the original where the sampling locations are slightly jittered, so the ...
27 views

### MRI image reconstruction - reduced scan pecentage

I have an MRI kspace from a siemens 1.5 T scanner with reduced scan percentage ( sampled truncation by not acquiring the most peripheral lines in kspace). The kspace plot in matlab look like below. I ...
10 views

### Pascal Voc 2012 Annotaions for 6D viewpoint(pose) estimation

Everyone, I am working on 6D pose estimation and I have to predict a rotation matrix (Euler angle) and translation. Now In Pascal Voc annotations are in the form of azimuth, elevation and distance ...
17 views

### How to choose $\lambda$ is compressed sensing

I am trying to reconstruct a signal using basis pursuit denoising of the compressed sensing framework (which is basically lasso), $\min\limits_{x} \frac{1}{2} || y − Ax||_2^2 + \lambda ||x||_1$. Here, ...
79 views

### How to extract a smooth contour from a set of points in 3D?

I am trying to segment a 3D volume. The outcome of all my volume segmentation algorithms is a set of candidate points in 3D space. Now I need to smooth this point cloud and fit a closed surface it. My ...
36 views

### What are the constraints in design of discrete orthogonal wavelets?

Can anyone point me to literature that explains a quote from here : Why is a wavelet transform implemented as a filter bank? So not all wavelets can be implemeted perfectly (invertible) with ...
318 views

### Recover Audio from Spectrogram Image

I have applied transformation(Constant Q Transformation) to my audio time domain signal, this gives me Frequency vs Time representation. Now, the CQT values consists of complex values(84*260), but ...
55 views

### What's wrong with this Whittaker-Shannon-Kotel’nikov interpolation implementation?

I tried to implement Whittaker-Shannon-Kotel’nikov interpolation formula but I get unexpected results: the reconstructed signal lags with respect to the original. I know that I can not expect a ...
60 views

### Proving Nyquist Sampling theorem for strictly bandlimited signals

I understand that the Nyquist sampling theorem dictates that the minimum sampling frequency, $f_s$, be s.t. $f_s > 2B$, where $B$, is the bandwidth of the signal. I have read the explanation for ...
45 views

### Very basic question about filters in signal reconstruction

I am studying digital signal processing and I would like to ask a question about sampled signal -> original signal reconstruction filters. Most textbooks use a box filter or a tent filter to show how ...
227 views

### What is Finite Rate of Innovation Signal?

I have read about Finite Rate of Innovation signal by Martin Vetterli in here. But i do not understand several basic things The paper said that finite rate of innovation is the number of degree of ...
180 views

### Multiple-image dense point cloud reconstruction with camera extrinsics/intrinsics

I have the following data available: Images from different angles X, Y, Z, pitch, yaw, and roll for each camera/image, together with the timestamp Lens distortion parameters and intrinsic camera ...
167 views

### Is it possible to generate depth map from graycode sequence without using printed calibration patterns?

In a camera-projector system, if only the camera's intrinsics are known, is it possible to generate the depthmap fully automatically through a graycode sequence without any manual calibration process (...
864 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 ...
250 views

### signal reconstruction [closed]

I'm new to DSP so the question might seem a little bit stupid: When using a low pass filter (say Butterworth filter) with Python, I came across an algorithm with which I can reconstruct my signal ...
257 views

### What Are the Types of Deconvolution?

I am totally new to image processing and wanted to ask you if you could confirm what I understood. It is about deconvolution: From what I read we find 2 main types of deconvolution: 1. Analytical <...
134 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 ...
50 views

### Construct a signal that is multiplied by a white noise?

Can we reconstructs a signal after it is being multiplied (not added) by a random noise (not with the normal distribution)? Lets say I have S=10*sin(2*pi*5*t) for t=[0:.001:1] and I have a random ...
242 views

### Confused on application of Anti-Aliasing Filter

I have a question about the use of anti-aliasing filters prior to sampling a finite time signal and if they actually help anything. The point of the anti-aliasing filter is to remove high-frequency ...
173 views

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### 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 ...
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 ...
392 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 ...
95 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 ...