def to_hash
      h = {:width => width, :height => height, :bits => bits, :comment => comment}
      h.merge!(exif) if exif?
      h
    end
def to_hash
      h = {:width => width, :height => height, :bits => bits, :comment => comment}
      h.merge!(exif) if exif?
      h
    end
Get a hash presentation of the image.