Questions tagged [gaussian]

For issues related to any of the uses of the Gaussian function. Don't forget to add additional tags to clarify the context.

The graph of a Gaussian is a characteristic symmetric "bell curve" shape that quickly falls off towards plus/minus infinity. The 1-D Gaussian is defined as (taken from wikipedia):

gaussian function from wikipedia

The parameter a is the height of the curve's peak, b is the position of the centre of the peak, and c controls the width of the "bell".

In multiple dimensions, the Gaussian is defined as the product of 1D curves along each dimension.

Gaussian functions are widely used in statistics where they describe the normal distributions, in signal processing where they serve to define Gaussian filters, in image processing where two-dimensional Gaussians are used for Gaussian blurs, in mathematics and physics where they are used to solve heat equations and diffusion equations, to formulate the propagation of optical beams (Gaussian beams), to from a basis set of wavefunctions, to define the Weierstrass transform, and many more.

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OpenMP C Normal Random Generator

I was doing a C assignment for parallel computing, where I have to implement some sort of Monte Carlo simulations with efficient tread safe normal random generator using Box-Muller transform. I generate 2 vectors of uniform random numbers X and Y,…
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Expectation Maximization opencv-Log Likelihood value

I'm estimating the parameters of a GMM using EM, When I use my Matlab script And run the EM code i get a single value of "log-likelihood".. However in opencv the output of EM.train gives a matrix which contained the loglikelihood value of every…
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Image remains unchanged after convolution

I'm attempting to perform Gaussian blur calculations based on source from the AForge framework. At present though I have something wrong with my calculations in that I am getting the same pixel data out of the process as I am putting in. (Something…
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MATLAB Figure file

I have a problem with contour figure, when I run my syntax I get error like: Error using contourf (line 66) Z must be size 2x2 or greater. Error in example (line 660) contourf (x,y,c); colorbar; and this is my…
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matlab-Adding gaussian noise using pdf

I am trying to add gaussian noise to an image using the pdf model. I have searched for hours but the only thing I get is either imnoise or a manual code as below: Inoise = Orig_img + (sqrt(variance)*randn(size(Orig_img)) + mean); The pdf for…
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Can shared Random instance be used to get Gaussian distribution

In java class there is random instance that is shared between two methods. public class Utils{ Random rand = new Random(); public double nextGaussian1(){ return rand.nextGaussian(); } public double nextGaussian2(){ …
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Matlab remove noise

I want to remove noise from an image. The image i've been given is a .mat file but it's very complicated because when i load the mat file no image can be seen, then i use imwrite to make it jpg imwrite(destroyedImg, 'fr.jpg'); But when i use imshow…
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Weight parameter in GMM and Expectation Maximization

I am working in programming of GMM with EM. I am stuck with the following problem. As you will see in this website, there is a parameter "pi" which is in other words the weight or probability value. My question is how is this calculated? Or is it…
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Gaussian bluring differentiable by X and Y

Help me get the 3 * 3 matrix of coefficients of the Gaussian filter, differentiable by X and Y. Is it just 0 0 0 -1 0 1 0 0 0 or not?
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OpenCV: how to get GMM parameters?

I am using BackgroundSubtractorMOG2 to do background subtraction, and I've manually set the number of mixture model to be used as follows: cv::BackgroundSubtractorMOG2 myModel; myModel.set("nmixtures",5); Now I want to display the actual mixture…
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How to fit gaussian with Matlab with given height

I am currently unable to have accurate gaussian fit. How can I fix the height? (see picture). ft=fit(x,y,'gauss2') Co=coeffvalues(ft) sigma=Co(3)/sqrt(2) mu = Co(2) C=Co(1) plot(X,C*exp(-(X - mu).^2 / (2*sigma^2))+min(y), '-r')
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Fitting A Gaussian Curve to a Time Series in Matlab

I have some raw data of vegetation indices of a place. When I plot them on a time series I get a result as follows: Now we can fit some Gaussian Model which is of the form Where "n" is the number of terms/Gaussian. Matlab does provide this kind…
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emgu diffence of gaussian filter returns black image

I'm trying to implement DoG filter in emgu like this: Image temp = inImage; Image temp2 = inImage; temp1._SmoothGaussian(1); temp2._SmoothGaussian(3) result= temp2.Sub(temp); result.ToBitmap().Save("DoG.bmp"); Problem is…
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Gaussian blur not uniform

I have been trying to implement a simple Gaussian blur algorithm, for my image editing program. However, I have been having some trouble making this work, and I think the problem lies in the below snippet: for( int j = 0; j < pow(…
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Matlab illustration for Gaussian Mixture Model using contour3 or anything

I have fitted a 3D data set (x1, x2,x3) using Gaussian Mixture Model. Now I have the pdf as well. How can I illustrate this fitting in matlab? I was trying to use contour3, but it requires nXm matrix and my data are all 40000x1. For…
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