P_2_1_4_01 Use an image to check on/off a grid of checkboxes Shout out to Dan Shiffman's checkbox mirror example Image credits: Map tiles by Stamen Design, under CC BY 3.0. Data by OpenStreetMap, under ODbL. KEYS 1 : load image shapes 2 : load image letters 3 : load image map SLIDER drag : drag the slider to adjust the image threshold CONTRIBUTED BY Joey Lee INSPIRED BY Dan Shiffman