Hey guys, TL;DR format:

I'm trying to make a simple interactive drawing program where you write on a sheet of notepaper as the background with a big pencil following your cursor. Problem: the drawing doesn't stay because the background refreshes or something like that. Either that, or both the drawing AND pencil get printed onto the screen.

Can anyone help me get the drawing to stay WITHOUT the pencil burning itself onto the screen along with the drawing?
Source code & video below. Thanks!

Video

1.     PImage img;
       PImage bg;
   
       void setup() {
         size(1280, 1007);
   
         bg = loadImage ("note_paper_right.jpg");
         img = loadImage ("Clipart.png");
   
       }
   
       void draw() {
   
           image (bg, 0, 0); 
           image (img, mouseX, mouseY - 390);
         
            stroke(0);
            strokeWeight(4);
            smooth();
   
          if (mousePressed) {
            line(pmouseX, pmouseY, mouseX, mouseY);
         }
       }