%% dwuliniowa
img = double(img);
nImg = double(nImg);
for y=0:(nYY-1)
   y1 = floor(y*yStep);
   y2 = y1 + 1;
   yy = y*yStep - y1;
   if y2 > (YY-1)
    y2 = YY-1;
   end

   for x=0:(nXX-1)
       x1 = floor(x*xStep);
       x2 = x1 + 1;
       xx = x*xStep - x1;
       if x2 > (XX-1)
        x2 = XX-1;
       end
       nImg(y+1,x+1) = [1-xx xx]*[img(y1+1, x1+1) img(y2+1, x1+1); img(y1+1, x2+1) img(y2+1, x2+1)] * [1-yy; yy];
   end
end