About What The Colors Mean
To clarify what the colors mean, we map the following ICMP Response types (taken from RFC-792) to colors:
(yuri, please fill in table of type -> color)
In cases where each pixel represents multiple addresses, we mix the red, green, and blue components in proportion to the single-address colors. (We drop any yellow colors unless all addresses are yellow.) We adjust the brightness to correspond to the fraction of red and green addresses.