title: How to find width of (1D discrete) Gaussian Kernel for a certain sigma?
body: <p>Is there a rule of thumb or mathematical equation that tells me how wide my (1D discrete) Gaussian Kernel should be for a certain sigma?</p>
  
  <p>Lets say, I choose a sigma of 1.87, should my kernel be 5 values/steps/pixels wide, 7 oder rather 25 in order to perform standardized image smoothing? Thank you.</p>