In 3.6.2.4.2 Image Pattern, it says...
"Note: This pattern uses an image to get the gray values. If you want exactly
the same possibilities but need to get gray values from a pigment, you can use
the --pigment_pattern--."
That pigment_pattern link is incorrect; it leads to 3.6.1.1.3 Pigment Map
instead. The correct link should be 3.6.2.1.19 Pigment Pattern.
