math - Difference of Gaussian in Edge detection -

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can tell me how 2-d gaussian function given as-

http://upload.wikimedia.org/math/f/7/3/f7352f2a6fea01707e869432d39bfc21.png

where t standard deviation.

  1. how convoluted image(as in difference of gaussian)?
  2. what difference between gaussian function , gaussian filter?

based on formula filter mask constructed in (aka discrete version of gaussian function):

http://homepages.inf.ed.ac.uk/rbf/hipr2/gsmooth.htm

this example gaussian filter mask:

enter image description here

1).

this how convolution filter mask done:

http://www.songho.ca/dsp/convolution/convolution2d_example.html

basically filter flipped , filter moves on image. while moving on image, image pixel corresponds middle of mask gets value of weighted sum of mask , pixels. ( link explains better example)

2).

gaussian function ==> continues

gaussian filter ==> in case, discrete filter mask


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