# 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 ...
• 6,670
Accepted

• 7,590
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 ...
• 47k

### DAC - Can we create and use frequencies above Fs/2?

DAC - Can we create and use frequencies above Fs/2? yes, that's commonly done. You can work with any image you want, as long as it's pronounced enough (in the end, as long as the analog bandwidth of ...
Accepted

### DAC - Can we create and use frequencies above Fs/2?

In addition to the good points Marcus has made in his answer, I want to add that there are other DAC topologies specific for doing this more efficiently. The OP is correct that a traditional (Non-...
• 53.9k
Accepted

### 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 ...
• 1,736
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.
• 1,736

### 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,...
• 263
Accepted

### Reconstructing Signal From Its Cyclic Autocorrelation

No, you cannot reconstruct the original signal from the cyclic autocorrelation. The fundamental reason is that it results from an averaging operation. Like the autocorrelation and PSD, the cyclic ...
• 106
Accepted

### 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 ...
• 1,417
Accepted

### What is the difference between image restoration and image reconstruction?

The use might depend on authors. From one of my colleagues, Jean-Christophe Pesquet, supported by the book Image Reconstruction: Algorithms and Analysis by Fessler, especially Chapter 1: Image ...
• 32.1k
Accepted

### MRI image reconstruction - reduced scan pecentage

I would say no, there isn't. This is unmeasured information and you cannot compute it without additional information (ie some additionally sampled data, and maybe some compressed sensing algorithm). ...
• 1,736