fprintf(myfile, sprintf('method=sobel threshold=%.02f precision=%.04f \n', threshold, precision_sobel));
    myfile = fopen('precision.txt', 'a+');
    fprintf(myfile, sprintf('method=roberts threshold=%.02f precision=%.04f \n', threshold, precision_roberts));
    myfile = fopen('precision.txt', 'a+');
    fprintf(myfile, sprintf('method=canny threshold=%.02f precision=%.04f \n', threshold, precision_canny));