# Questions tagged [reconstruction]

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### 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. ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 back-...
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### 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 ...
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### 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 ...
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### Three Projective Cameras in the Same “Projective Frame” - What Can I Do With This Info?

[I originally posted this under Mathematics, but I didn't get any replies. I thought I'd try here.] In Hartley & Zisserman's Multiple View Geometry in Computer Vision, in the chapter on trifocal ...
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### Power Spectral Density Reconstruction

I am from an ML background and I am working on MP3 audio reconstruction and I have managed some amount of spectrogram reconstruction but I have noticed that the higher frequency end of the generated ...
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### sampling using L1 optimization

As much as I understand the F should be the interval medians (correct me if I wrong), according to the next slide, where is also the Loss function defined: What I don't understand is the next note in ...
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### Find the frequencies present when a non-sinusoidal wave is reconstructed

A 1.6kHz periodic (not sinusoidal) signal contains all its harmonics, both even and odd. The signal is sampled at 3.6kHz and ideally reconstructed. What frequencies are present in the output? I know ...
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### 3D reconstruction of moving object

I am pretty new to the field of 3D reconstruction and overwhelmed by the large amounts of different methods. I am trying to find the correct method for my use case: Setting: I have a stationary ...
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### Reconstruct a signal via continuous wavelet transform (CWT)

I want to use the continuous wavelet transform (CWT) to modify the amplitude of a signal in the frequency domain (in a specific frequency band) and then reconstruct the signal. I want to do it by ...
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### 2D IFFT implementation

I have a problem where I need to obtain 2D IFFT of a $81\times64$ signal. However, if we denote the reconstructed image $I_{m,n}$, its coordinates will be $M\times N$ but the k-space signal is sampled ...
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### Reconstruction of sampled band-pass signal

I am pretty new to signal processing. I am currently trying to reconstruct a sampled band-pass signal created with the filtfilt and ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...