Flipping only certain part of an image

I need to flip the part of an image that the user decides. I need to iterate through the array and flip it, I can use the flip pre defined function.The whole picture needs to be showing, you cant crop the part they want and just flip that, so a section of the picture will be flipped and the rest is normal.

Answer 1

[Walter Roberson]

M(rows, cols, :) = appropriate_flip(M(rows, cols, :)) ;

for appropriate function appropriate_flip (there are multiple ways to flip)