proc extractColor color if scan color 2x 2x 2x red blue green return l

proc extractColor {color} {
  if {[scan $color "#%2x%2x%2x" red blue green] == 3} {
    return [list $red $blue $green]
  }

  return {}
}

# puts [extractColor #1A3FAB]

proc packColor {red blue green} {
  return [format "#%2x%2x%2x" $red $blue $green]
}

# puts [packColor 255 255 255]

proc calcColor {r g b brightPnc} {
  return [list [expr round($r * ($brightPnc / 100.0) * 0.3) % 255]  \
               [expr round($g * ($brightPnc / 100.0) * 0.59) % 255] \
               [expr round($b * ($brightPnc / 100.0) * 0.11) % 255]]
}

# puts [packColor {*}[calcColor {*}[extractColor "#66AC2E"] 30]]