This is going to be kind of hard to follow so here goes. I just finished the drawing on the right. My goal was to draw what a photo negative of the car would look like. In other words, draw the car where the light values are dark and the dark values are light. After completing the drawing I scanned it into my computer using imaging software. In short...I drew the image on the right using pencil. The image on the left was created by inverting the values of my drawing on the right. Confusing huh! HA
Not as complicated as it sounds but it's a great way of checking my drawing technique.