Patent ID: 7602525

Claim:
An image processing device comprising: a first color conversion unit that converts RGB image data to CMY image data; a color conversion table storing unit that stores at least a color conversion table produced by a color conversion table producing device; a second color converting unit that converts the CMY image data to CMYKcm data on the basis of the color conversion table, which is selected by a color conversion table selecting unit and which is read from the color conversion table storing unit; wherein said image processing device carries out image processing using said color conversion table produced by obtaining ink-quantity vectors I p , which are retained by a certain grid point “p” and which minimize a smoothing level evaluation function E used for evaluating a smoothing level at respective lattice point data after color conversion by the color conversion table, at the respective grid points, wherein said smoothing level evaluation function E includes an evaluation function Eit based on a twisted quantity of an ink-quantity vector before and after the conversion using the color conversion table, wherein the evaluation function Eit is represented as a mathematical expression (A-1-3), E it = ∑ t = 1 T ⁢ ∑ r = 1 R ⁢  I p + I ptr - I pr - I pt D t  2 (A-1-3) and wherein “t” is a suffix, which denotes a certain grid point p t , “T” denotes the number of p t , “r” is a suffix, which denotes a certain grid point p r , “R” denotes the number of p r , D t denotes a transition distance at “t,” the respective grid points “p,” p r , p t , and P tr retain ink-quantity vectors I p , I pr , I pt , and I ptr , a grid point neighboring a certain grid point “p” is denoted as p r , a grid point other than the grid point p r neighboring the grid point “p” is denoted as p t and a grid point which has the same positional relationship with the grid point p t as the grid point “p” has with the grid point p r is denoted as P tr .