color[] shadeTable;
void setColor(color c) {
  float r, g, b;
  r = red(c);
  g = green(c);   
  b = blue(c);  
  r /= 255.;
  g /= 255.; 
  b /= 255.;
  println(r);
  shadeTable = new color[256];
  for( int i = 0; i < 255; i++ )
    shadeTable[i] = color((int)(r*i),(int)(g*i),(int)(b*i));
}

void setup(){
  size(255,100);
  setColor(color(255,0,0));
  for( int i = 0; i < 255; i++ ){
    fill(shadeTable[i]);
    noStroke();
    rect(i,0,1,100);
  }
}