canali c;
int w = 320;
int l = 240;
int counter_r = 0;
int counter_v = 0;
int counter_b = 0;
int ris = 0;

void setup()
{
  size(w, l);
  smooth();
  stroke(255);
  frameRate(10000);
  c = new canali(255,255,255);
  background(0);
  fill(255,255,255);
  rect(0,0,310,240);
}

void draw()
{
  checksfondo();
}

void checksfondo()
{
  c.getcolor();
  ris = ((w*l)*70)/100;
  while (c.totcolori > ris)
  {
     fill(0,0,0);
     rect(10,10,20,20);
  }
}

public class canali
{
    public float rosso;
    public float verde;
    public float blu;
    public float totcolori;

    canali(int r,int v,int b)
    {
        rosso = r;
        verde = v;
        blu = b;
    }
        void getcolor()
        {
                for (int x=0;x<w;x++)
                 {
                for (int y=0;y<l;y++)
                       {
                        color grab = get(x,y);
                        rosso = red(grab);
                        verde = green(grab);
                        blu   = blue(grab);
                        if (rosso > 200)
                        {
                        counter_r++;
                        }
                        if (verde > 200)
                        {
                        counter_v++;
                        }
                        if (blu > 200)
                        {
                        counter_b++;
                        }
                       totcolori = counter_r+counter_v+counter_b;
                        }
               }
        }
}