1. Field of the Invention
The present invention relates to a color prediction method, a color conversion lookup table generation method, an image processing method and an image processing apparatus, and more particularly, to color correction technology for image forming data in color image formation.
2. Description of the Related Art
In general, in an inkjet recording apparatus or an image forming apparatus based on an electrophotographic method, a plurality of coloring materials, such as yellow (Y), magenta (M), cyan (C) and black (K) are used. The color space achieved by these coloring materials is different to that of the original image data, and therefore color conversion (color correction) processing is carried out in order to faithfully reproduce the colors and tones represented by the original image data.
On the other hand, depending on the characteristics of the output medium for image formation, there are limits on the amount of coloring material that can be received by the medium. For example, when forming a color image on a paper medium using an inkjet recording apparatus, deformation of the paper medium occurs if ink of an amount exceeding the amount that can be absorbed by the paper medium is deposited thereon. Due to this deformation of the paper medium, there is a risk of the occurrence of conveyance abnormalities of the paper medium, and decline in the quality of an image formed on the paper medium.
Furthermore, even if the paper does not deform, when an excessive amount of coloring material is used, coloring material may not be fixed satisfactorily on the medium, leading to degradation of the film properties and reduced resistance to rubbing, and problems such as transfer to the rear surface of other media may occur when media are stacked after image formation.
Japanese Patent Application Publication No. 2004-58623 discloses a method according to which, when generating a color separation table (a table used for color separation processing to calculate a coloring material use amount from signal values) on the basis of data obtained by color measurement of patches, if there is a patch having a coloring material use amount greater than a maximum overall coloring material use amount specified on the basis of the ink absorption characteristics of a recording medium, and the like, then a color separation table within the range of the maximum overall coloring material use amount is generated by compressing the signal values in such a manner that all of the patches come within the range of the maximum overall coloring material use amount.