US Patent 7234793 Image printing using print quality enhancing ink

Image quality is improved by adjusting the ejection amount of quality enhancing ink based on the ejection amount of colored ink containing colorant. When a relatively high gross printing medium is used, the quality enhancing ink is ejected in an image area where virtually no colored ink is ejected, thereby improving unevenness in gloss within the print image. When a relatively low gross printing medium is used, on the other hand, the quality enhancing ink is ejected in an image area where the colored ink is ejected on virtually all pixels, thereby improving unevenness in color within the print image. The relationship between the ejection amounts of the quality enhancing ink and the colored ink may be modified by the user.