def area(type=true)
      if type
        number = (@narray.eq 1).where.length
      else
        number = (@narray.eq 0).where.length
      end
      # Total area is number of pixels times the area per pixel:
      return number * @image.pixel_area
    end
def area(type=true)
      if type
        number = (@narray.eq 1).where.length
      else
        number = (@narray.eq 0).where.length
      end
      # Total area is number of pixels times the area per pixel:
      return number * @image.pixel_area
    end
Calculates the area defined by true/false (i.e. 1/0) pixels.
 By default, the area of the 'true' pixels are returned.

 @param [Boolean] type pixel type of interest (i.e. the 'true' or 'false' pixels)
 @return [Float] the calculated area (in units of millimeters squared)