The Picture Book Colour Index
The Colour Index shows the change of the two main shades throughout the whole Picture Book Edition. Each double line corresponds to a single book of the edition (from A to Z).
Every line consists of 150 ribbons showing the colour value of the first square on every page (placed in the upper left matrix corner) for main shade 1 (upper stripe) and main shade 2 (lower stripe).
The figure illustrates the colour evolution over the 26 books of the Picture Book Edition running along 390.000.000 digits of Ludolph's Number.