Ink-jet printing method and apparatus
AssigneeCanon Kabushiki Kaisha
InventorsMasataka Yashima, Tsuyoshi Shibata
Life of this patent
Estimating the term…
Abstract
When multilevel printing is performed by using a plurality of types of inks, which present different densities for similar colors when used for printing, and changing the types of inks and the numbers of ink droplets in printing each pixel, an ink distribution table which defines a combination of the types of inks and the numbers of ink droplets in correspondence with each gray level value is generated on the basis of input information associated with the relative densities of the respective inks. A combination to be used to print each pixel is selected on the basis of the ink distribution table, thereby printing a good grayscale image free from gray-level reversal and the like.
Claims13
An ink-jet printing apparatus which performs multilevel printing by using a plurality of types of inks having different densities for similar colors when used for printing, and changing the types of inks and the numbers of ink droplets in printing each pixel, comprising:
- input means for inputting information associated with relative densities for the respective inks in case of being used for printing;
- table generation means for generating, on the basis of the information associated with the relative densities, an ink distribution table for defining a combination of the types of inks and the numbers of ink droplets in correspondence with each gray level value;
- combination selection means for selecting, on the basis of the ink distribution table, the combination to be used to print each pixel, wherein the ink distribution table defines a plurality of combinations of the types of inks and numbers of the ink droplets for some grey level value;
- and
- reference combination input means for inputting a combination of the types of inks and the numbers of ink droplets which exhibit a predetermined density as a reference combination, wherein said table generation means generates, on the basis of information associated with the relative densities and the reference combination, the ink distribution table which defines a correspondence between various combinations of the types of inks and the numbers of ink droplets and gray level values printed by the respective combinations,
- wherein said table generation means includes reference value calculating means for expressing the sum of the ratios with respect to ink droplets contained in each combination as a density reference value with respect to the sum of the ratios with respect to ink droplets contained in the reference combination, and conversion means for converting the density reference value into the gray level value.
An ink-jet printing method which performs multilevel printing by using a plurality of types of inks having different densities for similar colors when used for printing, and changing the types of inks and the numbers of ink droplets in printing each pixel, comprising:
- an input step of inputting information associated with relative densities for the respective inks in case of being used for printing;
- a table generating step of generating, on the basis of the information associated with the relative densities, an ink distribution table for defining a combination of the types of inks and the numbers of ink droplets in correspondence with each gray level value;
- a combination selection step of selecting the combination to be used to print each pixel on the basis of the ink distribution table, wherein the ink distribution table defines a plurality of combinations of the types of inks and numbers of the ink droplets for some grey level;
- and
- a reference combination input step of inputting a combination of the types of inks and the numbers of ink droplets which exhibit a predetermined density as a reference combination, wherein in the table generating step, on the basis of information associated with the relative densities and the reference combination, the ink distribution table is generated which defines a correspondence between various combinations of the types of inks and the numbers of ink droplets and gray level values printed by the respective combinations,
- wherein the table generating step includes a reference value calculating step of expressing the sum of the ratios with respect to ink droplets contained in each combination as a density reference value with respect to the sum of the ratios with respect to ink droplets contained in the reference combination, and a conversion step of converting the density reference value into the gray level value.
Dependencies are inferred from the claim text.