whats the concept behind 2 d median filtering of an image

my code is

v=[ 154 138 163

   75   74  151

   70  106  118]

my output is

t =[ 0 75 0

   74  118  106

    0   74    0]

whats the logic behind this?

[Sivakumaran Chandrasekaran]

the steps are arranging in ascending order. zero should be added to the edges. I cant understand the remaining positions

Answer 1

[Image Analyst]

For example, when the window is centered over the right middle pixel (row 2, column3), the window sees

138 163 0
 74 151 0
106 118 0

and the median value of those numbers is 106. Perhaps this will illustrate:

theWindow = [v(:,2), v(:,3), [0;0;0]]
rightMiddleElement = median(theWindow(:))

Is this not the logic you were expecting?