## Top new questions this week:

### How does Delta-Sigma Modulation convert a 1-bit signal to higher resolution signal?

I've looked at various resources about Delta-Sigma modulators, and I find them fascinating. However, I'm confused on a particular point and and am looking for an explanation. In my understanding, …

sampling

### How can I perform object tracking using noisy images?

The problem Take 50+ of Lena images, add gaussian noise to them to the point that you couldn't say it is Lena. I insist, gaussian noise, not gaussian blurring. Now imagine a cropping window randomly …

image-processing video-processing

### Removing unwanted peaks from signal

I have a signal which looks something like: The 12 main round peaks is what I'd like to keep. However, the peak detection algorithm I apply is picking up the in-between noisy peaks. Any strategies …

noise signal-analysis signal-detection peak-detection

### Fitting fixed number of complex exponentials to complex signal

I have a complex data series, and I would like to fit a fixed number (in this case, two) of complex exponentials of the form $Ae^{jBn}$, where A, B are complex. Not interested in the phase (i.e. arg …

discrete-signals frequency estimation

### Image gradient computation by convolution matrix

Prewitt operator is a common operator to compute image gradient in edge detection, and I knew that to apply this Prewitt operator to an image is just to convolve them together, say, the image is …

image-processing convolution

### Eigenvalues and eigenvectors of a 3D image Laplacian

I need to compute the eigenvalues and eigenvectors of a 3D image Laplacian. All the information and examples I have read are for 2D images. The specific questions are: How can I obtain a 2D matrix …

image-processing 3d

### SNR calculation in audio reconstruction and what is an acceptable value

I have the original signal, a .wav file and by blind source separation, i have reconstructed the signal. How can I calculate the SNR in this case? or is it good to use any other performance …

audio source-separation

## Greatest hits from previous weeks:

### How to estimate a transfer function from a magnitude-only frequency response?

Given an arbitrary frequency response, what signal processing methods might exist that could guess, estimate or determine a transfer function (pole and zero constellation) which gives a "reasonably …

transfer-function frequency-response zeros

### Why should I zero-pad a signal before taking the Fourier transform?

In an answer to a previous question, it was stated that one should zero-pad the input signals (add zeros to the end so that at least half of the wave is "blank") What's the reason for this?

fft

### Harmonics on periodic functions

Ok I need to understand how some harmonic calculations work to apply some transforms. If I have a periodic functiion f(x). And I have the values of that function for several values of x (say x goes …

transform
Define an $n\times N$ sensing matrix $A$ by $A_{ij} = 0$ with probability $p$, and $A_{ij} = 1/\sqrt{n}$ with probability $1-p$. Does $A$ satisfy the restricted isometry property? For reference, the …