LWS = imread ('lws.jpg');
PrewittHor = [1 1 1; 0 0 0; -1 -1 -1];
NachbarRangeS = ceil(length (PrewittHor) /2);
[sizeHor sizeVer] = size(LWS);
[fzeilen fspalten] = size (PrewittHor);
for cols = 1 : sizeVer
    for rows = 1 : sizeHor
          Ausgangsmatrix (rows + NachbarRangeS, cols + NachbarRangeS) = sum (sum (LWS(rows: (rows +(fZeilen-1)), cols: (cols + (fSpalten-1))) .* PrewittHor));
    end
end
imshow (Ausgangsmatrix);