[=] ->
Arg X, Y : RGBColor,
    . : CLR_BRIGHTNESS, - Result = 0 ..

Brightness_X = ( X.Red + X.Green + X.Blue ) / 3
Brightness_Y = ( Y.Red + Y.Green + Y.Blue ) / 3

Precision = 1 / 2^8

If Brightness_X = Brightness_Y, Precision then 
 _
Else
 If Brightness_X > Brightness_Y, Precision then 
  Result = 1
 Else
  Result = -1
 ;
;

Return
