title: Optimal sigma for Gaussian filtering of an image?
body: <p>When applying a Gaussian blur to an image, typically the sigma is a parameter (examples include Matlab and ImageJ). </p>
  
  <p>How does one know what sigma should be? Is there a mathematical way to figure out an optimal sigma? In my case, i have some objects in images that are bright compared to the background, and I need to find them computationally. I am going to apply a Gaussian filter to make the center of these objects even brighter, which hopefully facilitates finding them. How can I determine the optimal sigma for this?</p>