Elements of the gaussians functions

Last time I worked with Gaussians functions was a long time ago, so I know that this is a stupid question but I can't find the answer anywhere. It's about the elements of the Gaussian functions. Here you can see everything:

The first line is what I want to implement. The second line is the definition of the Gaussian function, where 0 is the mean and the sigma^2 is the variance, but I can't find anywhere where is the 'point' or as shown in the first formula dn.

Thank you very much for your help with this easy/novice question

[Star Strider]

The reference you got those from should explain the symbols and notation.

[Óscar]

Yes Star, and it says what is each thing, but I don't understand what is the dn inside the formula. For example, in Matlab you have: GAUSSMF(X, [SIGMA, C]) = EXP(-(X - C).^2/(2*SIGMA^2)); Where X are the points where the gaussian function is evaluated. So what I'm wondering is if that 'dn' are also the points where the function is evaluated.

[Image Analyst]

Like I said in my answer below, they have C as 0 and dn is X-C = X. I think you should concentrate on the concept and not so much on the confusing notation.

Answer 1

[Image Analyst]

I don't know what that first equation is but it looks like a filter of some kind (convolution, correlation, spatial, linear). If you have the Image Processing Toolbox, you can get the gaussian from fspecial(), and do the filtering with conv2() or imfilter().

[Óscar]

OK thank you, but i mean in the 2nd function which is the first part of the ()?

Thanks

[Image Analyst]

I think it would be x or dn, which is basically the distance from the center of the hump since the mean is at 0.