def b=(value)
      if typecode < RGB_
        decompose( 2 )[] = value
      elsif typecode == OBJECT
        self[] = Hornetseye::lazy do
          r * RGB.new( 1, 0, 0 ) + g * RGB.new( 0, 1, 0 ) + value * RGB.new( 0, 0, 1 )
        end
      else
        raise "Cannot assign blue channel to elements of type #{typecode.inspect}"
      end
    end
def b=(value)
      if typecode < RGB_
        decompose( 2 )[] = value
      elsif typecode == OBJECT
        self[] = Hornetseye::lazy do
          r * RGB.new( 1, 0, 0 ) + g * RGB.new( 0, 1, 0 ) + value * RGB.new( 0, 0, 1 )
        end
      else
        raise "Cannot assign blue channel to elements of type #{typecode.inspect}"
      end
    end
Assignment for blue channel values of RGB array

 @param [Object] Value or array of values to assign to blue channel.

 @return [Object] Returns +value+.