Before moving from black and white to color, we explore the tones between white and black. How many steps are there? In graphic arts technology, printers use 10 that they can hold with their presses: 1 white, 8 steps of tones then solid black. How many can the human eye perceive?
Human eyes have two photoreceptors: rods and cones. We have about 120 million rods that perceive only black or white and about 6 million cones that perceive color. Cones are less sensitive to light and can be divided into red (64%), green (32%) and blue (2%) based on measured response curves.
Some people can create 23 or more steps between black and white by mixing black into white acrylic paint pigment on white illustration board. We typically paint a rectangle of illustration board white then paint one black and try to get as many steps as possible between. After that exercise, we move to image creation. Who has not felt joy when viewing a beautiful black and white silver photograph with a full range of tones?
We play with image capture by painting with only white or black paint. Here are some student examples. Many students have never painted before but seem to enjoy this exercise anyway.