img=;

ImageData[img]

n=10;
Image[
ListConvolve[ReplacePart[Table[((-1)/((((2n+1))^2)-1)), 2n+1,2n+1,1], {n+1,n+1,1} -> 1],
ImageData[img]]
] // ImageAdjust

ListConvolve[ReplacePart[Table[(1/((((2n+1))^2)-1)), n,n,1], {n+1,n+1,1} -> -1],
ImageData[img]]