The tag has no usage guidance.

learn more… | top users | synonyms

0
votes
1answer
35 views

Gaussian wavelet generation of a given frequency

How can I generate a Gaussian wavelet (time domain) with a given central frequency. I mean, if I take the Fourier Transform then its spectrum should be around that given central frequency. For ...
0
votes
0answers
27 views
+50

Gaussian filter of 2d image with location dependant sigma in Python

I am trying to implement in Python a Gaussian filter in which the kernel is $$ G(x,y) = \frac{1}{2 \pi \sigma_0^2} e^{-\frac{(x-x')^2 + (y-y')^2}{2 (\sigma_0 f(x',y'))^2}},$$ where $f(x,y)$ is some ...
3
votes
1answer
75 views

Is $A\cos(\omega t+\theta)$ a Gaussian random process?

$Z(t) = A\cos(\omega t+\theta)$ where $A$~$N(0,\sigma ^2) $ and $\theta $~$(0,2\pi)$ are independent. I'm trying to figure out if $Z(t)$ is a Gaussian random process and whether it is strict sense ...
0
votes
0answers
24 views

Gaussian signal / image smoothing at sigma 0.5

I am currently reading up on Lowe's paper [1] on SIFT keypoint detection. On the page labeled 97 he mentions We assume that the original image has a blur of at ...
0
votes
1answer
20 views

Gaussian filter in terms of pixel radius

So I'm writing an app that blurs and downscales large quantities of images, but all the image processing libraries I've come across define gaussian blurs in terms of sigma and kernel size rather than ...
0
votes
2answers
46 views

what is a Gaussian signal?

I am learning Wiener filtering for 2D images by myself. From one book, it reads It should be noted that the study of the more general problem of signal denoising dates back to at least Norbert Wiener ...
1
vote
1answer
36 views

Implementing a 1-D Kalman Filter Regression, Missing the smoothing action (getting the opposite)

I am implementing the 1D Kalman Filter in Python on a fundamentally noisy set of measurement data, and I should be observing a large amount of smoothing...but, instead, my Kalman Filter is doing the ...
1
vote
1answer
30 views

How do I calculate the autocorrelation of a train pulse having only the pdf?

I have a pulse train of a fixed period, but a random amplitude following a Gaussian distribution $(\mu=0,\sigma=1)$. I know how to work with a random period or delay, but how do I proceed to calculate ...
0
votes
1answer
16 views

How to make a 2D gaussian Blur terms?

I want to make a 2D gaussian Blur coeffients. Now I am making 1D gaussian Blur term as following. ...
1
vote
0answers
12 views

Curve fitting to distorted Gaussian

I have to measure the distance between two pulse trains, each of which looks like a slightly long tailed Gaussian distribution. Is there a relatively easy curve fitting method for this? I can do it ...
1
vote
1answer
46 views

Mutual information of $ \infty $-PAM

I'm trying to compute using matlab the mutual information for an $ \infty $-PAM input (the limit of a very dense PAM constellation) for a range of snr and I got stuck. I'm working with a real-valued ...
2
votes
0answers
85 views

Difficulty in understanding the log-likelihood expression in Expectation Maximization

UPDATE : Question based on the paper Maximum likelihood for blind separation and deconvolution of noisy signals using mixture models pdf download link Assume the model is a FIR system of order 2 ...
0
votes
0answers
26 views

Calculating 3x3 Gaussian kernel

I have problems understanding/calculating one particular question in my exercises. This is the exercise: I know a) and I believe b) to be $[0.950, 1.33[$ c) is where I am currently stuck. I guess ...
1
vote
0answers
19 views

How to write code for learning of a model(train a model) in matlab with Gaussian distribution where input is data set of images (120 images) [closed]

Purpose is to find $P(f_k/f_{k-1})$ for a given data set of bunch of images where $f_k$ is the fixation value of images data set.The code is related to machine learning where I have to train a model ...
1
vote
1answer
43 views

How to derive the $\log$ of fraction of two Gaussian distribution

I am designing a function $A(x)$ that map $x\to \{0,1\}$. The function $A$ can be expressed as $$A(x)=\begin{cases} 1 \text{ if $p_1(x) \ge p_2(x)$}\\ 0 \text{ otherwises} \end{cases} $$ where ...
1
vote
0answers
60 views

OpenCV's BackgroundSubtractorMOG algorithm parameters

Does anyone know what the history and number of Gaussian mixtures do in the Gaussian Mixture-based Background/Foreground Segmentation Algorithm used in OpenCV? I'm trying to optimise a background ...
1
vote
1answer
17 views

What is the equivalent smoothing function to running the same Gaussian 8 times?

Suppose there is an image which is to be smoothed by convolving it with a Gaussian kernel with standard deviation $\sigma$. If the image is then smoothed with this kernel 8 consecutive times, is the ...
0
votes
0answers
24 views

Implementation of HMM with continuous emission

I have a classification problem that, based on continuous features from a 1D signal, should classify to a finite amount of stages (discrete). There is a temporal evolution in the signal, so I am ...
0
votes
1answer
17 views

How will a Gaussian Blur affect Image Variance

I am trying to find a way to analytically estimate how the noise (or variance in pixel values) will be affected for a zero-frequency image of random noise after applying a Gaussian blur. In more ...
0
votes
1answer
45 views

Uniform quantizer for gaussian input signal

I have a gaussian signal $x$ with zero mean and unit variance. I am quantizing it by using a uniform quantizer of step size $q$ calculated by $$q = \frac{x_\mathrm{max} - ...
0
votes
1answer
34 views

Plotting uniform and Gaussian random variables

I want to create uniform and Gaussian (normal) random variables in MATLAB via rand and randn syntax. And I would like to plot ...
0
votes
1answer
50 views

What is the most efficient way to perform Gaussian blurs for varying sizes of Gaussian kernels in an image?

I have detected corner points of images using Harris corner detector in GLSL and now, I intend on using Fast Retina Keypoint(FREAK) as keypoint descriptor to later match the keypoints between images. ...
0
votes
2answers
23 views

How does gaussian convution stacking work?

If I first convolve an image with a Gaussian filter with σ = 1, and then convolve the output of that image with a Gaussian with σ = 2 Does this give the same effect as convolving the original image ...
1
vote
1answer
31 views

Multiscale Shape and Detail Enhancement from Multi-light Image Collections

I have been working on a practical implementation in Matlab of the algorithm Raanan Fattal suggested in the following paper. I couldn't understand the meaning of eq. 11 on page 5: g is a gaussian, ...
1
vote
1answer
57 views

How can I implement image widowing in my image in Java?

My initial image is a medical image and my main objective is finding directionality. The original size of my image was 8X8 and I have rescaled the image to 32X32 to increase my accuracy. My input ...
0
votes
1answer
46 views

Power spectrum of downsampled image

I am not sure if this is the right stackexchange community for this question, but here goes. I am generating a Gaussian Random Field (GRF) of a pre-defined power spectrum. In the image below, the ...
1
vote
2answers
115 views

gaussian filter close to image border

When applying gaussian filters close to the borders of an image, algorithms usually zero-pad or replicate/mirror/wrap the borders. This is not good enough for my case, so I wonder if there is ...
1
vote
1answer
45 views

equations to calculate coefficients of recursive IIR Gaussian blur filter

I am reading the implementation of IIR Gaussian blur filter from this link. In the source code, the coefficients are generated by the following code ...
0
votes
0answers
113 views

frequency response of Gaussian filter

In Matlab, the function freqz can produce frequency response in terms of transfer function and the function freqz2 can produce frequency response for FIR filter. It seems that I can's use the input ...
1
vote
1answer
49 views

Complex Gaussian Channel + AWGN noise

If I define a channel to have complex Gaussian coefficients, do I still need to add noise to the signal passing through this channel using the command "awgn" or would that be redundant?
1
vote
5answers
140 views

filter coefficients to know high pass and low pass filter

Looked on few questions already there in dsp.stackexchange and couldn't get the direct answer. Basically I have a kernel of a gaussian separable filter. ...
0
votes
0answers
12 views

Questions about channel modeling

I'm trying to model a statistical wssus channel using data collected from a ray propagation simulator. These are the following information I know : - 4 taps - each tap has 8 samples - each sample has ...
1
vote
1answer
528 views

Question about Difference of Gaussian (DoG) algorithm

I am recently learning about Computer Vision and I am having a trouble understanding Difference of Gaussian (DoG) algorithm. I get how the algorithm works in high level idea, but I am trying to ...
0
votes
1answer
88 views

Downsampling and Gaussian filtering in the context of scale space pyramids

In the context of scale space image pyramids using Gaussian filters I noticed that it's common to downsample the image after blurring with $\sigma = 2*\sigma_{init}$ . My question is: What is the ...
0
votes
1answer
74 views

Gaussian in matlab

I have written a function that implements a gaussian filter. I use fft2 to transform my image and my filter to 2d fourier transform. Then I multiply them and then use ifft2. The resulting image is ...
0
votes
0answers
116 views

Deriche recursive filter using OpenCV

Is it possible to create a Deriche recursive filter using opencv (the Deriche filter is a blur that minimizes noise and preserves edges for later edge detection)? I can create one using CPU code, but ...
0
votes
1answer
55 views

SURF feature extractor and descriptor

I am trying to understand how SURF extracts features using a Hessian matrix. What I am a bit confused about, is why a second derivative Gaussian filter is used, rather than a standard Gaussian ...
0
votes
1answer
65 views

FFT function of Gaussian pulse

I need gaussian pulse fft. I set the sigma of gaussian pulse 1e-10 and define the gaussian function in time and use the fft. as you know the amplitude of should be unit in frequency domain. but my ...
0
votes
0answers
13 views

Gaussian filter at different order?

What effect does the Gaussian have at different order.. I mean comparing a Gausian Kernel with at 2. order Gaussian kernel.. What benefits, or when would it be appropriate to take the derivative.. ?? ...
0
votes
1answer
81 views

How to calculate Gaussian kernel for a small pixel size?

How to calculate the values of Gaussian kernel? I think I understand the principle of it weighting the center pixel as the means, and those around it according to the $\sigma$ but what would each ...
0
votes
2answers
96 views

Why/How a Gaussian Channel is both band-limited and Power limited?

All physical channels are band-limited, such that, X(f) = 0 for |f| > W A Gaussian Channel is limited in both power and bandwidth. For this reason we encounter phrases, such as, "A band-limited ...
0
votes
1answer
39 views

Can we decompose a correlated random variable into correlated plus uncorrelated?

Assume a random sequence $ Y_k = X_k \cdot H_k + W_k $ where $X_k$ is a deterministic quantity, $H_k$ is a correlated random sequence, $W_k$ is Additive White Gaussian random sequence. Can we ...
0
votes
1answer
221 views

Applying Gaussian Blur in frequency domain

Please see second update I'm trying to implement gaussian blur in frequency domain using c#. Those are steps that I'm doing: Load bitmap. Split bitmap into separate color channels. Convert every ...
0
votes
1answer
96 views

Is there a closed form expression for noise other than white noise?

For white noise, where the PSD is constant, we can model that as a simple Gaussian. Is there any way to model the probability density function of other types of noise (pink noise, red noise, blue ...
0
votes
1answer
39 views

What type of sensors have complex Gaussian noise?

What type of sensors have complex Gaussian noise? Do strain gauges also exhibit such noise?
1
vote
0answers
50 views

Effect of Gaussian Smoothing to mean image intensity

I am implementing Perona-Malik Diffusion in using the formulas: Creating image at time k+1 using equation This is my implementation: ...
1
vote
1answer
28 views

How to determine stopband of discrete Gaussian, stdev sigma, support N

I would like to analyse a gaussian smoothing kernel with a set standard deviation and support (let's say, in MATLAB, fspecial('gaussian', [5 1], 1.3) so sigma is 1.3 and support is 5) in the DTFT ...
0
votes
0answers
27 views

Relation between Gaussian and Savitsky-Golay kernels

I would like to make a mathematical comparison between two methods in my field. One smooths with a Gaussian filter, and one smooths using a second-order Savitsky-Golay filter. Let's say the window ...
2
votes
3answers
138 views

Gaussian noise generator algorithm trouble

I stumbled upon the following algorithm for Gaussian noise generation and I just can't figure out how this is supposed to work at all. The algorithm is as follows: First of all: $j = \arg\min_i ...
1
vote
2answers
81 views

imshow command for Gaussian function

I'm trying to plot 2D gaussian function using "imshow" in MATLAB. However I could not see any white points in image. I tried to change sampling values and limits of x and y values. In addition to ...