Printing system and method of recording images

Claim 2

A printing system in accordance with claim 1, wherein said one type of dots selected among said at least two types of dots having different hues and processed by said first dot formation determination means are dots of a color having a greater visual effect.

Claim 3

A printing system in accordance with claim 1, wherein said one type of dots selected among said at least two types of dots having different hues are dots of one color component included in three primary colors that can express a full color, whereas said another type of dots having a different hue are dots of another color component included in said three primary colors.

Claim 4

A printing system in accordance with claim 1, wherein said one type of dots selected among said at least two types of dots having different hues are dots of one color component included in three primary colors that can express a full color, whereas said another type of dots having a different hue are dots of a color including said one color component and another color component.

Claim 5

A printing system in accordance with claim 1, wherein said first dot formation determination means comprises means for determining either one of formation and non-formation of said one type of dots, which has been selected among said at least two types of dots having different hues, based on said input tone signal of a color corresponding to said one type of dots, prior to the determination with respect to said another type of dots having a different hue, said second dot formation determination means comprising means for determining either one of formation and non-formation of said another type of dots having a different hue, when said first dot formation determination means determines non-formation of said one type of dots.

Claim 6

A printing system in accordance with claim 1, wherein said first dot formation determination means comprises means for determining either one of formation and non-formation of said one type of dots, which has been selected among said at least two types of dots having different hues, based on said input tone signal of a color corresponding to said one type of dots, prior to the determination with respect to said another type of dots having a different hue, said second dot formation determination means comprising means for determining non-formation of said another type of dots having a different hue, when said first dot formation determination means determines formation of said one type of dots.

Claim 7

A printing system in accordance with either one of claims 5 and 6, said printing system further comprising error diffusion means for calculating a difference between a first printing density, which corresponds to said input tone signal relating to said another type of dots and regarding a target pixel, and a second printing density, which is realized by said another type of dots in said target pixel, as a density error, based on the determination of either one of formation and non-formation of said another type of dots by said second dot formation determination means, and distributing said density error into peripheral pixels that are in proximity to said target pixel, in order to enable said density error to affect the determination of either one of formation and non-formation of said another type of dots by said second dot formation determination means with respect to said peripheral pixels.

Claim 8

A printing system in accordance with claim 7, wherein said error diffusion means comprises density difference calculation means for, when said first dot formation determination means determines formation of said one type of dots, calculating said difference between the first printing density corresponding to said input tone signal relating to said another type of dots and the second printing density realized by said another type of dots, as a value representing a degree of correlation of hues between said one type of dots and said another type of dots.

Claim 9

A printing system with a head for forming at least two types of dots having different hues on an object, said printing system recording a multi-tone image through a distribution of said dots, said printing system comprising: input means for successively inputting multi-color tone signals regarding pixels included in an image to be printed; first dot formation determination means for carrying out multi-valued coding with respect to one type of dots selected among said at least two types of dots having different hues, based on said input tone signal of a color corresponding to said one type of dots, and determining either one of formation and non-formation of said one type of dots; local error calculation means for calculating a local difference between a first printing density, which corresponds to said input tone signal relating to said one type of dots and regarding a target pixel, and a second printing density, which is realized by said one type of dots in said target pixel, based on the result of multi-valued coding carried out by said first dot formation determination means; second dot formation determination means for enabling the local difference to affect a recording density to be realized by another type of dots having a different hue, carrying out multi-valued coding with respect to said another type of dots according to the recording density, and determining either one of formation and non-formation of said another type of dots; and head drive means for driving said head based on the results of determination by said first dot formation determination means and said second dot formation determination means, thereby actually forming said at least two types of dots having different hues.

Claim 10

A printing system in accordance with claim 9, wherein said local error calculation means comprises: first degree of effect calculation means for calculating a first degree of effect of the first printing density, which corresponds to said input tone signal relating to said one type of dots and regarding said target pixel, upon a printing density by said another type of dots having a different hue; second degree of effect calculation means for calculating a second degree of effect of the second printing density, which is realized by said one type of dots in said target pixel, upon the printing density by said another type of dots having a different hue; third degree of effect calculation means for calculating a third degree of effect of a density error upon the printing density by said another type of dots having a different hue, based on the determination of either one of formation and non-formation of said another type of dots with respect to peripheral pixels that are in proximity to said target pixel, said density error representing a difference between a printing density corresponding to the input tone signals relating to said another type of dots and regarding said peripheral pixels and a printing density realized by said another type of dots in said peripheral pixels; and means for calculating said local difference by taking into account the first degree of effect, the second degree of effect, and the third degree effect respectively calculated by said first, second and third degree of effect calculation means.

Claim 11

A printing system in accordance with either one of claims 9 and 10, wherein said one type of dots selected among said at least two types of dots having different hues and processed by said first dot formation determination means are dots of a color having a greater visual effect.

Claim 12

A printing system in accordance with either one of claims 9 and 10, wherein said one type of dots selected among said at least two types of dots having different hues are dots of one color component included in three primary colors that can express a full color, whereas said another type of dots having a different hue are dots of another color component included in said three primary colors.

Claim 13

A printing system in accordance with either one of claims 9 and 10, wherein said one type of dots selected among said at least two types of dots having different hues are dots of one color component included in three primary colors that can express a full color, whereas said another type of dots having a different hue are dots of a color including said one color component and another color component.

Claim 14

A printing system in accordance with claim 9, said printing system further comprising error diffusion means for calculating a difference between a third printing density, which corresponds to said input tone signal relating to said another type of dots and regarding said target pixel, and a fourth printing density, which is realized by said another type of dots in said target pixel, as a density error, based on the determination of either one of formation and non-formation of said another type of dots by said second dot formation determination means, and distributing said density error into peripheral pixels that are in proximity to said target pixel, in order to enable said density error to affect the determination of either one of formation and non-formation of said another type of dots by said second dot formation determination means with respect to said peripheral pixels.

Claim 15

A printing system in accordance with any one of claims 1 through 14, wherein either one of said first dot formation determination means and said second dot formation determination means applies a dither method to determine either one of formation and non-formation of dots.

Claim 16

A printing system in accordance with claim 15, wherein the dither method applied by either one of said first dot formation determination means and said second dot formation determination means utilizes a threshold matrix of discrete dither.

Claim 17

A printing system in accordance with any one of claims 1 through 14, wherein said head is able to discharge at least two types of inks having different densities, with respect to at least two color inks having different hues, at least either one of said first dot formation determination means and said second dot formation determination means carrying out multi-valued coding for each type of dots selected among at least two types of dots having different densities per unit of area and formed by said at least two types of inks having different densities, and determining either one of formation and non-formation of said each type of dots.

Claim 18

A printing system in accordance with claim 17, wherein said at least two types of inks having different densities comprise a higher-density ink and a lower-density ink and a dye density of said lower-density ink is approximately one quarter a dye density of said higher-density ink.

Claim 19

A printing system with a head for forming at least two types of chromatic color dots of different hues by at least two chromatic color inks as well as achromatic color dots by an achromatic color ink on an object, said printing system recording a multi-tone image through a distribution of said dots, said printing system comprising: input means for successively inputting tone signals regarding pixels included in an image to be printed; density calculation means for calculating densities by said at least two chromatic color inks and a density by said achromatic color ink, based on the input tone signals; achromatic color dot formation determination means for carrying out multi-valued coding with respect to said achromatic color ink based on the density by said achromatic color ink calculated by said density calculation means, and determining either one of formation and non-formation of achromatic color dots by said achromatic color ink; density correction means for obtaining correction data, which are to reflect the densities by said at least two chromatic color inks, based on the result of multi-valued coding with respect to said achromatic color ink, and correcting the densities by said at least two chromatic color inks; chromatic color dot formation determination means for carrying out multi-valued coding with respect to said at least two chromatic color dots of different hues, based on the corrected densities by said at least two chromatic color inks, and determining either one of formation and non-formation of said at least two chromatic color dots of different hues; and head drive means for driving said head based on the results of determination by said achromatic color dot formation determination means and said chromatic color dot formation determination means, thereby actually forming said at least two chromatic color dots of different hues by said at least two chromatic color inks as well as said achromatic color dots by said achromatic color ink.

Claim 20

A printing system in accordance with claim 19, said printing system further comprising error diffusion means for calculating a difference between a first printing density, which corresponds to the input tone signals relating to said achromatic color dots and said at least two chromatic color dots and regarding a target pixel, and a second printing density, which is realized by said achromatic color dots and said at least two chromatic color dots in said target pixel, as a density error, based on the determination of either one of formation and non-formation of said achromatic color dots by said achromatic color dot formation determination means and of said at least two chromatic color dots by said chromatic color dot formation determination means, and distributing said density error into peripheral pixels that are in proximity to said target pixel, in order to enable said density error to affect the determination of either one of formation and non-formation of said at least two chromatic color dots by said chromatic color dot formation determination means with respect to said peripheral pixels.

Claim 21

A printing system in accordance with any one of claims 1, 9, and 19, wherein said head comprises a mechanism for discharging ink particles under a pressure applied to each ink running through an ink conduit by application of a voltage to a piezoelectric element arranged in said ink conduit.

Claim 22

A printing system in accordance with any one of claims 1, 9, and 19, wherein said head comprises a mechanism for discharging ink particles under a pressure applied to each ink running through an ink conduit by air bubbles that are produced by a supply of electricity to a heating body arranged in said ink conduit.

Claim 26

An image display apparatus for forming at least two types of dots having different hues on an object and expressing a multi-tone image through a distribution of said dots, said image display apparatus comprising: input means for successively inputting multi-color tone signals regarding pixels included in an image to be displayed; first dot formation determination means for carrying out multi-valued coding with respect to one type of dots selected among said at least two types of dots having different hues, based on said input tone signal of a color corresponding to said one type of dots, and determining either one of formation and non-formation of said one type of dots; second dot formation determination means for enabling the result of multi-valued coding carried out by said first dot formation determination means to affect a display density to be realized by another type of dots having a different hue, carrying out multi-valued coding with respect to said another type of dots according to the recording density, and determining either one of formation and non-formation of said another type of dots; and dot formation means for actually forming said at least two types of dots having different hues, based on the results of determination by said first dot formation determination means and said second dot formation determination means.