def best_color_settings
      if black_and_white?
        [ChunkyPNG::COLOR_GRAYSCALE, 1]
      elsif grayscale?
        if opaque?
          [ChunkyPNG::COLOR_GRAYSCALE, 8]
        else
          [ChunkyPNG::COLOR_GRAYSCALE_ALPHA, 8]
        end
      elsif indexable?
        [ChunkyPNG::COLOR_INDEXED, determine_bit_depth]
      elsif opaque?
        [ChunkyPNG::COLOR_TRUECOLOR, 8]
      else
        [ChunkyPNG::COLOR_TRUECOLOR_ALPHA, 8]
      end
    end
def best_color_settings
      if black_and_white?
        [ChunkyPNG::COLOR_GRAYSCALE, 1]
      elsif grayscale?
        if opaque?
          [ChunkyPNG::COLOR_GRAYSCALE, 8]
        else
          [ChunkyPNG::COLOR_GRAYSCALE_ALPHA, 8]
        end
      elsif indexable?
        [ChunkyPNG::COLOR_INDEXED, determine_bit_depth]
      elsif opaque?
        [ChunkyPNG::COLOR_TRUECOLOR, 8]
      else
        [ChunkyPNG::COLOR_TRUECOLOR_ALPHA, 8]
      end
    end
Determines the most suitable colormode for this palette.
 @return [Integer] The colormode which would create the smallest possible
  file for images that use this exact palette.