Color separation into a plurality of ink components including primary color ink and spot color ink

Abstract

Utilizing an ink set that includes a plurality of chromatic primary color inks that, when used in combination, can reproduce achromatic color, and at least one spot color ink of hue different from any of the plurality of chromatic primary color inks. Color to be reproduced on a print medium according to any one input color is termed “reproduction color”, and the combination of ink quantities in the ink set for reproducing the reproduction color on the print medium is termed the “color separation ink quantity set.” The ink quantity of the spot color ink included in the color separation ink quantity set is adjusted in accordance with a lightness parameter value which is correlated to lightness of reproduction color, so as to reduce ink quantity at a rate of change greater than the rate of change of the lightness parameter in the direction of increasing brightness.

1 . A printing apparatus comprising:
 a print controller that performs printing of an image on a print medium using an ink set, the ink set including a plurality of chromatic primary color inks and at least one spot color ink, the plurality of chromatic primary color inks being capable of reproducing achromatic color when used in combination, the plurality of chromatic primary color inks including a first ink and a second ink, the spot color ink having a hue different from any of the plurality of chromatic primary color inks, the hue of the spot color ink being capable of being reproduced by a combination of the first ink and the second ink, wherein   the print controller performs printing of a first color without the spot color ink, the first color having a predetermined hue between a hue of the first ink and a hue of the spot color ink, the first color having a predetermined lightness and a predetermined saturation, and   the print controller performs printing of a second color with the spot color ink, the second color having a predetermined hue being closer to the hue of the first ink than the hue of the first color is, the second color having the same lightness and the same saturation as the first color.   
   
   
       2 . A printing apparatus comprising:
 a print controller that performs printing of an image on a print medium using an ink set, the ink set including a plurality of chromatic primary color inks and at least one spot color ink, the plurality of chromatic primary color inks being capable of reproducing achromatic color when used in combination, the plurality of chromatic primary color inks including a first ink and a second ink, the spot color ink having a hue different from any of the plurality of chromatic primary color inks, the hue of the spot color ink being capable of being reproduced by a combination of the first ink and the second ink, wherein   in a case where the print controller performs printing of a plurality of first colors having a first hue between a hue of the first ink and a hue of the spot color ink, a predetermined saturation and mutually different lightness:
 the print controller performs printing of the first color lighter than a first lightness with the spot color ink; and 
 the print controller performs printing of the first color darker than the first lightness with the spot color ink, and 
   in a case where the print controller performs printing of a plurality of second colors having a second hue being closer to the hue of the first ink than the first hue is, the predetermined saturation and mutually different lightness:
 the print controller performs printing of the second color lighter than a second lightness lighter than the first lightness without the spot color ink; and 
 the print controller performs printing of the second color darker than the second lightness with the spot color ink. 
   
   
   
       3 . A printing apparatus comprising:
 a print controller that performs printing of an image on a print medium using an ink set, the ink set including a plurality of chromatic primary color inks and at least one spot color ink, the plurality of chromatic primary color inks being capable of reproducing achromatic color when used in combination, the plurality of chromatic primary color inks including a first ink and a second ink, the spot color ink having a hue different from any of the plurality of chromatic primary color inks, the hue of the spot color ink being capable of being reproduced by a combination of the first ink and the second ink, wherein   in a case where the print controller performs printing of a plurality of first colors having a first hue between a hue of the first ink and a hue of the spot color ink, a predetermined saturation and mutually different lightness:
 the print controller decreases an ink quantity of the spot color ink at a first variation as lightness becomes higher to perform printing of the first color lighter than a first lightness; and 
 the print controller decreases the ink quantity of the spot color ink at a second variation as lightness becomes higher to perform printing of the first color darker than the first lightness, the second variation being smaller than the first variation, 
   in a case where the print controller performs printing of a plurality of second colors having a second hue being closer to the hue of the first ink than the first hue is, the predetermined saturation and mutually different lightness:
 the print controller decreases the ink quantity of the spot color ink at a third variation as lightness becomes higher to perform printing of the second color lighter than a second lightness lighter than the first lightness; and 
 the print controller decreases the ink quantity of the spot color ink at a fourth variation as lightness becomes higher to perform printing of the second color darker than the second lightness, the fourth variation being smaller than the third variation. 
   
   
   
       4 . A printing apparatus comprising:
 a print controller that performs printing of an image on a print medium using an ink set, the ink set including a plurality of chromatic primary color inks and at least one spot color ink, the plurality of chromatic primary color inks and at least one spot color ink, the plurality of chromatic primary color inks being capable of reproducing achromatic color when used in combination, the plurality of chromatic primary color inks including a first ink and a second ink, the spot color ink having a hue different from any of the plurality of chromatic primary color inks, the hue of the spot color ink being capable of being reproduced by a combination of the first ink and the second ink, wherein   the print controller performs printing of a first color with a first quantity of the second ink, the first color having a first hue between a hue of the first ink and a hue of the spot color ink, and   the print controller performs printing of a second color with a second quantity of the second ink, the second color having a second hue being closer to the hue of the first ink than the hue of the first color is, the second quantity being smaller than the first quantity.   
   
   
       5 . A printing apparatus comprising:
 a print controller that performs printing of an image on a print medium using an ink set, the ink set including a plurality of chromatic primary color inks and at least one spot color ink, the plurality of chromatic primary color inks being capable of reproducing achromatic color when used in combination, the plurality of chromatic primary color inks including a first ink and a second ink, the spot color ink having a hue different from any of the plurality of chromatic primary color inks, the hue of the spot color ink being capable of being reproduced by a combination of the first ink and the second ink, wherein   a difference of an ink quantity of the second ink is greater than a difference of an ink quantity of the spot color ink between printing of a first color and printing of a second color, the first color having a first hue between a hue of the first ink and a hue of the spot color ink, the second color having a second hue being closer to the hue of the first ink than the first hue is.