private void constructArr() {
		for (int i = 0; i < img.getWidth(); i++) {
			for (int j = 0; j < img.getHeight(); j++) {
				if (ImgUtil.isWhitePixel(img, i, j)) {
					propagate(i,j,0);
				}
			}
		}
		
		
		while(!actions.isEmpty()) {
			PopulateAction act = actions.get(0);
			propagate(act.x, act.y, act.value);
			actions.remove(0);
		}
	}