This is my entry for ColorChallenge - Saturday Indigo.
This photo was taken near Medvode, Slovenia.
Indigo is light you can see with a wavelength between 420 and 450 nanometers. That means it is between blue and violet. The closest thing I can think of to true indigo is a brand new pair of unwashed jeans. They are bluer than blue, yet not quite violet. Yes, they are often called "Blue Jeans," but Levi Strauss used a plant dye from the indigo plant to color them back in the 1800s and it has stuck.
