No, that’s not a Gaussian filter
Friday, February 6th, 2015
I recently got a question from a reader regarding Gaussian filtering, in which he says:
I have seen some codes use 3×3 Gaussian kernel like
h1 = [1, 2, 1]/4
to do the separate filtering.
The paper by Burt and Adelson (The Laplacian Pyramid as a Compact Image Code, IEEE Transactions on Communication, 31:532-540, 1983) seems to use 5×5 Gaussian kernel like
h1 = [1/4 - a/2, 1/4, a, 1/4, 1/4-a/2]
,and
a
is between 0.3-0.6. A typical value ofa
may be 0.375, thus the Gaussian kernel is:
h1 = [0.0625, 0.25, 0.375, 0.25, 0.0625]
or
h1 = [1, 4, 6, 4, 1]/16
.
I have written previously about Gaussian filtering, but neither of those posts make it clear what a Gaussian filter kernel looks like.