Patent ID: 8888214

Claim:
An image forming apparatus, which forms an image using a plurality of colors of colored inks which contain pigment color materials and have different refractive indices, and a plurality of types of colorless inks which contain colorless materials and have different refractive indices, comprising: a color separating means for acquiring colored ink data for respective colors of the colored inks by color separation processing for each pixel of input color image data; a colored dot layout means for setting, for each pixel, colored dot layouts of the respective colors of the colored inks according to tone levels of the respective colors indicated by the colored ink data; a colorless dot layout means for setting, for each pixel, a colorless dot layout for one of the plurality of types of colorless inks with reference to a colorless dot layout table using the colored ink data as indices; and an image forming means for forming a color image on a recording medium by recording, for each pixel, the respective colored inks in the colored dot layouts, and the colorless ink set by said colorless dot layout means of the plurality of types of colorless inks in the colorless dot layout, wherein in the colorless dot layout table, when a specular glossiness calculated according to the colored dot layouts for the colored ink data is higher than a predetermined target value, the colorless dot layout is set to superpose a colorless ink having a lowest refractive index on a colored ink having a highest refractive index, and when the specular glossiness is not more than the target value, the colorless dot layout is set to superpose a colorless ink having a highest refractive index on a colored ink having a lowest refractive index or on a recording medium exposed portion where none of colored ink dots are laid out.