In the following snippet the two versions (classic and analogic) are compared:

//  Classic version:
  void compute(){
    int black_neighbours = 0;
    for(int z=0; z < neighbours.length; z++)
      if(neighbours[z].rgb == black)
        black_neighbours ++;  

    switch(black_neighbours){
      case 0:
      case 1:
      case 4:
      case 5:
      case 6:
      case 7:
      case 8:
        to_color(white);
        break;
      case 2:
        to_color(rgb);
        break;
      case 3:
        to_color(black);
        break;
    }
  } 

// Analogic version
  void compute(){
    int[] medium_color = new int[] {0,0,0};
    for(int z=0; z < neighbours.length; z++)
      for(int c=0; c < 3; c++)
        medium_color[c] = medium_color[c] + neighbours[z].rgb[c];

    int medium_tone = 0;
    for(int c=0; c < 3; c++){
      medium_color[c] = medium_color[c] / neighbours.length;
      medium_tone = medium_tone + medium_color[c];
    }  

    medium_tone = medium_tone / 3;

    if (medium_tone > 191 || medium_tone < 128 ){
      to_color(white);
    }else if(medium_tone > 159 ){
      to_color(rgb);
    }else{
      to_color(black);
    }
  }

Next I went a step further using ‘medium color’ when the classic rules asked insted to keep the previous cell color. This lead to a general acceleration to white because the medium neighbours color is always more bright than pure black, to balance this behavior I expanded the range of medium_tones which results in black. Here’s the tuned code:

  void compute(){
    int[] medium_color = new int[] {0,0,0};
    for(int z=0; z < neighbours.length; z++)
      for(int c=0; c < 3; c++)
        medium_color[c] = medium_color[c] + neighbours[z].rgb[c];

    int medium_tone = 0;
    for(int c=0; c < 3; c++){
      medium_color[c] = medium_color[c] / neighbours.length;
      medium_tone = medium_tone + medium_color[c];
    }  

    medium_tone = medium_tone / 3;

    if (medium_tone > 191 || medium_tone < 80 ){
      to_color(white);
    }else if(medium_tone > 159 ){
      to_color(medium_color);
    }else{
      to_color(black);
    }
  }

Now a short video of this new behavior: