This is from the old wiki. I'm not really sure why you would do this, but if you want lots of colors, have at it.

######################################################################
#Below is a set of filter definitions for all of the possible color 
#combinations that barnowl can display on an 8-color system.
#
#You can paste the text below into a file and source it in barnowl 
#using the command:
#source /full/explicit/path/to/where/you/put/the/file
#
#Then, you can see how those color combinations will appear in your
#terminal with the command:
#
#show filters
#
#Ike

filter defaultred -c default -b red class defaultred
filter defaultgreen -c default -b green class defaultgreen
filter defaultyellow -c default -b yellow class defaultyellow
filter defaultblue -c default -b blue class defaultblue
filter defaultmagenta -c default -b magenta class defaultmagenta
filter defaultcyan -c default -b cyan class defaultcyan
filter defaultwhite -c default -b white class defaultwhite
filter defaultblack -c default -b black class defaultblack
filter reddefault -c red -b default class reddefault
filter redgreen -c red -b green class redgreen
filter redyellow -c red -b yellow class redyellow
filter redblue -c red -b blue class redblue
filter redmagenta -c red -b magenta class redmagenta
filter redcyan -c red -b cyan class redcyan
filter redwhite -c red -b white class redwhite
filter redblack -c red -b black class redblack
filter greendefault -c green -b default class greendefault
filter greenred -c green -b red class greenred
filter greenyellow -c green -b yellow class greenyellow
filter greenblue -c green -b blue class greenblue
filter greenmagenta -c green -b magenta class greenmagenta
filter greencyan -c green -b cyan class greencyan
filter greenwhite -c green -b white class greenwhite
filter greenblack -c green -b black class greenblack
filter yellowdefault -c yellow -b default class yellowdefault
filter yellowred -c yellow -b red class yellowred
filter yellowgreen -c yellow -b green class yellowgreen
filter yellowblue -c yellow -b blue class yellowblue
filter yellowmagenta -c yellow -b magenta class yellowmagenta
filter yellowcyan -c yellow -b cyan class yellowcyan
filter yellowwhite -c yellow -b white class yellowwhite
filter yellowblack -c yellow -b black class yellowblack
filter bluedefault -c blue -b default class bluedefault
filter bluered -c blue -b red class bluered
filter bluegreen -c blue -b green class bluegreen
filter blueyellow -c blue -b yellow class blueyellow
filter bluemagenta -c blue -b magenta class bluemagenta
filter bluecyan -c blue -b cyan class bluecyan
filter bluewhite -c blue -b white class bluewhite
filter blueblack -c blue -b black class blueblack
filter magentadefault -c magenta -b default class magentadefault
filter magentared -c magenta -b red class magentared
filter magentagreen -c magenta -b green class magentagreen
filter magentayellow -c magenta -b yellow class magentayellow
filter magentablue -c magenta -b blue class magentablue
filter magentacyan -c magenta -b cyan class magentacyan
filter magentawhite -c magenta -b white class magentawhite
filter magentablack -c magenta -b black class magentablack
filter cyandefault -c cyan -b default class cyandefault
filter cyanred -c cyan -b red class cyanred
filter cyangreen -c cyan -b green class cyangreen
filter cyanyellow -c cyan -b yellow class cyanyellow
filter cyanblue -c cyan -b blue class cyanblue
filter cyanmagenta -c cyan -b magenta class cyanmagenta
filter cyanwhite -c cyan -b white class cyanwhite
filter cyanblack -c cyan -b black class cyanblack
filter whitedefault -c white -b default class whitedefault
filter whitered -c white -b red class whitered
filter whitegreen -c white -b green class whitegreen
filter whiteyellow -c white -b yellow class whiteyellow
filter whiteblue -c white -b blue class whiteblue
filter whitemagenta -c white -b magenta class whitemagenta
filter whitecyan -c white -b cyan class whitecyan
filter whiteblack -c white -b black class whiteblack
filter blackdefault -c black -b default class blackdefault
filter blackred -c black -b red class blackred
filter blackgreen -c black -b green class blackgreen
filter blackyellow -c black -b yellow class blackyellow
filter blackblue -c black -b blue class blackblue
filter blackmagenta -c black -b magenta class blackmagenta
filter blackcyan -c black -b cyan class blackcyan
filter blackwhite -c black -b white class blackwhite