The mask sizemasks the number of filters. A larger size, corresponding to a larger convolution mass, as a rule, leads to a greater degree of filtration. As a kind of compromise for greater noise reduction, large filters also affect the quality of image details.
This is like a milestone. Now, coming to Gaussian filter, the main parameter is standard deviation. If you use a 2D filter at the edge of the mask, you probably want the scale to approach 0 .
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