1. An outputting apparatus for outputting an image, the apparatus comprising: a color image obtaining unit configured to obtain a color image having multiple colors; a first monochrome image generating unit configured to generate a plurality of monochrome images by applying a plurality of mutually different calculations to the color image; a contrast calculating unit configured to calculate respective contrasts for the plurality of monochrome images; and an outputting unit configured to output a monochrome image derived from the calculated contrasts having the greatest contrast, wherein the contrast calculating unit calculates contrast by calculating a gradation value for each pixel of a monochrome image, and wherein the plurality of mutually different calculations include respectively weighing gradation values of red R, green G, and blue B in the color image with respective weighting coefficients, r, g and b to obtain weighting gradation values and then adding the weighting gradation values.