Another G'MIC code for implementing DCCI2X algorithm

scale_dcci2x_new : -check "${1=1.15}>=0 && ${2=5}>=0" -skip ${3=0}
  -e[^-1] "Double xy-dimensions of image$?, using DCCI2x algorithm."
  -v - -repeat $! -l[$>]
    -r {2*w-(!$3)},{2*h-(!$3)},1,100%,4

    # Estimate diagonal values.
    -f "init(
          const threshold = $1;
          const exponent = $2;
          interpolation = 0;
          boundary = 1;
          drp() = -j(-3,-3) + 9*j(-1,-1) + 9*j(1,1) - j(3,3);
          urp() = -j(3,-3) + 9*j(1,-1) + 9*j(-1,1) - j(-3,3);
        );
        if (x%2==0 || y%2==0,i,
          d1 = sum(abs([
                   j(-1,-3) - j(-3,-1), j(1,-3) - j(-1,-1), j(3,-3) - j(1,-1),
                   j(-1,-1) - j(-3,1), j(1,-1) - j(-1,1), j(3,-1) - j(1,1),
                   j(-1,1) - j(-3,3), j(1,1) - j(-1,3), j(3,1) - j(1,3)
               ]));
          d2 = sum(abs([
                   j(-3,-3) - j(-1,-1), j(-1,-3) - j(1,-1), j(1,-3) - j(3,-1),
                   j(-3,-1) - j(-1,1), j(-1,-1) - j(1,1), j(1,-1) - j(3,1),
                   j(-3,1) - j(-1,3), j(-1,1) - j(1,3), j(1,1) - j(3,3)
               ]));
          ratio = (1 + d1)/(1 + d2);
          value = ratio>threshold ? drp(): # Up-right edge
                  ratio<(1/threshold) ? urp(): # Down-right edge
                 (w1 = 1/(1 + d1^exponent); w2 = 1/(1 + d2^exponent); (drp()*w1 + urp()*w2)/(w1 + w2)); # Smooth area
          value/=16)"

    # Estimate remaining values.
    -f "init(
          const threshold = $1;
          const exponent = $2;
          interpolation = 0;
          boundary = 1;
          hp() = -j(-3,0) + 9*j(-1,0) + 9*j(1,0) - j(3,0);
          vp() = -j(0,-3) + 9*j(0,-1) + 9*j(0,1) - j(0,3);
        );
        if ((x%2) + (y%2)!=1,i,
          d1 = sum(abs([
                   j(-1,-2) - j(1,-2),
                   j(-2,-1) - j(0,-1), j(0,-1) - j(2,-1),
                   j(-3,0) - j(-1,0), j(-1,0) - j(1,0), j(1,0) - j(3,0),
                   j(-2,1) - j(0,1), j(0,1) - j(2,1),
                   j(-1,2) - j(1,2)
               ]));
          d2 = sum(abs([
                   j(-2,-1) - j(-2,1),
                   j(-1,-2) - j(-1,0), j(-1,0) - j(-1,2),
                   j(0,-3) - j(0,-1), j(0,-1) - j(0,1), j(0,1) - j(0,3),
                   j(1,-2) - j(1,0), j(1,0) - j(1,2),
                   j(2,-1) - j(2,1)
               ]));
          ratio = (1 + d1)/(1 + d2);
          value = ratio>threshold ? vp() : # Horizontal edge
                  ratio<(1/threshold) ? hp() : # Vertical edge
                  (w1 = 1/(1 + d1^exponent); w2 = 1/(1 + d2^exponent); (vp()*w1 + hp()*w2)/(w1 + w2)); # Smooth area
          value/=16)"
  -endl -done -v +