Taking pictures every x seconds - Processing

import processing.video.*;

Capture cam;

int nb_seconds, nb_images;

void setup() {
  size(600, 400);
  cam = new Capture(this, 640,480,30);
  cam.start();
  // draw() will execute 1 time per second
  frameRate(1);
}

void draw() {
  if(cam.available()){
    nb_seconds++;
    if (nb_seconds%10 == 0) {
      // this will execute every 10 seconds
      nb_images++;
      cam.read();
      PImage pg = cam.get();
      pg.save("image_" + nb_images + ".png");
    }
  }
  image(cam, 0,0);
}