Update workaround for automatic random nick colors
For those who cannot use the automatic nick color change feature because the threshhold for accept contrast scores is too low, a possible workaround is to make a slight tweak to your background color.
The colors chosen for auto-color of nicks is based on what's the RGB shade of your background color, and depending on what that is, you can have more or fewer colors in the list of nick colors used.
The colors chosen seem to be chosen if they have a high-enough score in the formula described above. Because the accepted threshhold score is either set too low, or the formula doesn't really work for real life, there are several shades of blue that are chosen when the background color is 01 black, even though they contrast poorly visually with black. While 12/60 can be seen against black when your eyes are very close to the screen, the contrast drops off sharply when your head is arm's length away.
While nick colors are set to random, if you enter a channel with a lot of nicks in it, this can give you the list of colors chosen against your current background color:
//var %i $nick(#,0) | while (%i) { var %list $addtok(%list,$nick(#,%i).color,32) | dec %i } | echo -ag $sorttok(%list,32,n)
Note that this includes any colors given to nicks from other rules you may have set, such as forcing all @op to be a specific color.
A solution for people using 01 black as their background color is to realize that color 88 is identical to the default shade for 01 black, and as you increase from 88 to 97, these are increasingly lighter shades of gray, until you reach 98 which is a duplicate of 00 white. (Except 88 and 98 can't be changed like 01 and 00 can)
If you change your background color from 01 to 90 you'll find that most of the poorly contrasting blue nicks that were shown against 01 aka 88 are now gone. There may be some other nick colors that no longer contrast as well against the new dark-grey, or there may be another grey shade in that range which works better for you.
But the 'bad' nick colors can't be completely eliminated, because low-contrast-score colors will always be picked for random nicks, regardless of whatever RGB shade the background color uses.
