# Tag Info

Accepted

### Shannon interpolation formula for downsampled data with an "almost ideal" low pass filter

I don't get your downsample step when you downsampled by factor $M$. Let me go from scratch with the spectrum visualization below, with time domain, continuous frequency domain and discrete frequency ...
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Accepted

### Best parameter to estimate image reconstruction quality?

Since you say the π symbol will always be in the same place, you don't need to detect/locate it. You can compare per-pixel. You could calculate a correlation score against a model image. Since the ...

### Sampling frequencies calculated on paper and in MATLAB not matching

On paper, I've calculated a sampling frequency of at least 2 cycles/sec, since the frequency of my signal is bound between 0 and 1 cycles/sec. How did you figure out that one ? The Taylor expansion ...
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### Question about MRI signal construction

I would expect that you simply cut the outer parts of the image away. Certainly, there is always a hassle to figure out the proper pixel in the center, but that is a detail of the FT-algorithm ...
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### MRI reconstruction using windowing based apodization

You say: I have a 128 point one dimensional k-space samples... The hanning window is the same size as the k-space vector (256)... Make sure that you have the appropriate sizes in your algorithm. ...
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### How can a signal have two maximum frequency components?

$x(t)$ must be a band pass signal. Under certain conditions on the sampling frequency and its relation to the lower and upper band edges of the signal, $x(t)$ can be sampled at a frequency that is ...
Accepted

### Simulating noise in computed tomography reconstruction

The easiest, and probably most straight forward way, seems to add the noise in the measurement domain, hence the sinogram.

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

Let us first assume you can produce estimates of the camera state (position and attitude) via sensors, a filter like a Kalman Filter, and a (simple) model for the camera itself. Using this information,...
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### What is the general formula for radon back projection for a javascript implementation?

To implement projection the simplest way is to rotate your image then sum over a row or column. The simplest way to implement back projection is to take a line of your sinogram which is a projection ...