Color image forming apparatus using color compressed color data

Claim 2

A color image forming apparatus for obtaining a color image data representing each color of an original color image formed on an image input medium and forming on an image output medium a color image corresponding to the original color image, the image input medium and the image output medium having first and second gamuts, respectively, the first and second gamuts being defined as reproducible ranges of the image input medium and the image output medium, said color image forming apparatus comprising: image input means for inputting a color image data representative of a color of each picture element of the original color image, the color of the each picture element thus represented by the color image data being positioned inside of the first gamut; color distribution detecting means for detecting color distribution of the original color image to generate color distribution information of the original color image; control signal producing means for producing a control signal on the basis of the color image data, the control signal having a value corresponding to that obtained through selectively transforming the color image data in a color-compression transformation which is determined on the basis of the color distribution information of the original color image, so that a color represented by the control signal corresponding to the color of each picture element of the original color image is positioned inside of the second gamut; and image recording means for recording, on the basis of the control signal, the color represented by the control signal on the image output medium as a color image corresponding to the original color image.

Claim 3

The color image forming apparatus as claimed in claim 1, wherein the color distribution information of the original color image includes information of the color image data of the color of at least one picture element of the original color image with respect to the second gamut.

Claim 4

The color image forming apparatus as claimed in claim 2, wherein the color distribution information of the original color image includes information of a ratio of a first color difference between a predetermined objective achromatic color and a color of at least one picture element of the original color image with respect to a second color difference between the objective achromatic color and a boundary color of the second gamut.

Claim 5

The color image forming apparatus as claimed in claim 3, wherein said color distribution detecting means includes prescanning means for prescanning the original color image to sample a color image data of at least a picture element of the original color image to thereby calculate the first color difference.

Claim 6

The color image forming apparatus as claimed in claim 1, wherein said control signal producing means includes: color-compression means for selectively color-compressing a color represented by the color image data in such a manner that the color-compression means may color-compress at least such a color image data as having a color-distribution-dependent relationship with the second gamut, the color-distribution-dependent relationship being determined on the basis of the color distribution information of the original color image to thereby produce a replacing color image data; and calculation means for calculating the control signal based on one of the non-selected color image data and the replacing color image data.

Claim 7

The color image forming apparatus as claimed in claim 5, wherein said color-compression means selectively color-compresses the color represented by the color image data with a color-compression degree which is determined on the basis of the color distribution information of the original color image to thereby produce the replacing color image data.

Claim 8

The color image forming apparatus as claimed in claim 6, wherein the color distribution information of the original color image includes information of the color image data of at least one picture element of the original color image with respect to the second gamut.

Claim 9

The color image forming apparatus as claimed in claim 7, wherein said color distribution detecting means calculates a ratio of a first color difference M1 between a predetermined objective achromatic color and a color of at least one picture element of the original color image with respect to a second difference M2 between the objective achromatic color and a boundary color of the second gamut to thereby obtain a non-compression coefficient R defined by the following equation, ##EQU11## where n represents the number of the at least one picture elements and i represents each one of the at least one picture elements.

Claim 10

The color image forming apparatus as claimed in claim 8, wherein said color distribution detecting means includes prescanning means for prescanning the original color image to sample a color image data of at least a picture element of the original color image to thereby calculate the first color difference M1.

Claim 11

The color image forming apparatus as claimed in claim 9, wherein said color-compression means selectively shifts the color represented by the color image data in a direction toward the objective achromatic color to produce the replacing color image data in such a manner that said color-compression means may color-compress at least such a color image data as having a color-difference from the objective achromatic color equal to or larger than a value obtained by multiplying the second color difference M2 by the non-compression coefficient R of the original color image.

Claim 12

The color image forming apparatus as claimed in claim 10, wherein said color-compression means selectively shifts the color represented by the color image data in a the direction toward the objective achromatic color with a color-compression degree which is determined in accordance with the non-compression coefficient R of the original color image.

Claim 13

The color image forming apparatus as claimed in claim 5, wherein the calculation means of said control signal producing means further includes color-proofing means for transforming one of the non-selected color image data and the replacing color image data into the control signal.

Claim 14

The color image forming apparatus as claimed in claim 1, wherein said control signal producing means includes: storing means for storing plural groups of combination data, each group of the combination data consisting of a plurality of color data inputtable by said input means and a plurality of record signals for controlling said image recording means to record, on the image output medium, colors corresponding to colors represented by the respective color data, the colors represented by the color data being positioned inside of the first gamut and the colors represented by the record signals being positioned in the second gamut, the plural groups of the combination data corresponding to plural color distribution data generatable by said color distribution detecting means, respectively, each of the record signals of each of the groups of the combination data being obtained through selectively transforming the corresponding color data in a color-compression transformation determined on the basis of the corresponding color distribution data; and selecting means for selecting one group of the plural groups of combination data in accordance with the color distribution information of the original color image generated by said color distribution detecting means to thereby produce the control signal.

Claim 15

The color image forming apparatus as claimed in claim 13, wherein said selecting means includes judging means for judging which one of the plural color distribution data is equal to the color distribution information generated by said color distribution detecting means.

Claim 16

The color image forming apparatus as claimed in claim 14, wherein the selecting means of said control signal producing means includes means for calculating the control signal through an interpolative process on the basis of at least two record signals of the selected one group of combination data.

Claim 17

The color image forming apparatus as claimed in claim 15, wherein each of the record signals of each of the groups of the combination data is calculated through selectively color-compressing each of the plurality of color data in such a manner that at least such color data as having a color-distribution-dependent relationship with the second gamut may be color-compressed, the color-distribution-dependent relationship being determined dependently on the corresponding color distribution data, to generate a replacing color data and through calculating each record signal based on one of the non-selected color data and the replacing color data.

Claim 18

The color image forming apparatus as claimed in claim 16, wherein the record signals of each of the groups of the combination data are calculated through selectively color-compressing the color data with a color-compression degree, which is determined on the basis of the corresponding color distribution data, to generate the replacing color data.

Claim 19

A color image forming apparatus for obtaining a color image data representing each color of an original color image formed on an image input medium and forming on an image output medium a color image corresponding to the original color image, the image input medium having a first gamut and the image output medium having a second gamut, the first and second gamuts being defined as reproducible ranges of the image input medium and the image output medium, respectively, said color image forming apparatus comprising: image input means for inputting a color image data of a color of each picture element of the original color image, the color represented by the color image data being positioned inside of the first gamut; color distribution detecting means for detecting color distribution of the original color image to generate color distribution information of the original color image; color-compression parameter calculating means for calculating a color-compression parameter on the basis of the color distribution information of the original color image; color-compression means for selectively color-compressing the color image data by using the color-compression parameter to produce a replacing color image data in such a manner that said color-compression means may color-compress such a color image data as having a color-compression-parameter-dependent relationship with the second gamut, the color-compression-parameter-dependent relationship being determined on the basis of the color-compression parameter; color proofing means for color-proofing the color image data in the case where said color-compression means does not color-compress the color image data and for color-proofing the replacing color image data in the case where said color-compression means color-compresses the color image data to produce the replacing color image data, to thereby produce a control signal, the control signal representing color which corresponds to the color represented by the color image data and which is positioned inside of the second gamut; and image recording means for recording, on the basis of the control signal, the color represented by the control signal on the image output medium, to thereby record a color image corresponding to the original color image on the image output medium.

Claim 20

A color image forming apparatus for obtaining a color image data representing each color of an original color image formed on an image input medium and forming on an image output medium a color image corresponding to the original color image, the image input medium having a first gamut and the image output medium having a second gamut, the first and second gamuts being defined as reproducible ranges of the image input medium and the image output medium, respectively, said color image forming apparatus comprising: image input means for inputting a color image data of a color of each picture element of the original color image, the color represented by the color image data being positioned inside of the first gamut; color distribution detecting means for detecting color distribution of the original color image to generate color distribution information of the original color image; color-compression parameter calculating means for calculating a color-compression parameter on the basis of the color distribution information of the original color image; color-compression means for selectively color-compressing the color image data by using the color-compression parameter to produce a replacing color image data in such a manner that said color-compression means may color-compress such a color image data as having a color-compression-parameter-dependent relationship with the second gamut, the color-compression-parameter-dependent relationship being determined on the basis of the color-compression parameter; color proofing means for color-proofing the color image data in the case where said color-compression means does not color-compress the color image data and for color-proofing the replacing color image data in the case where said color-compression means color-compresses the color image data to produce the replacing color image data, to thereby produce a control signal, the control signal representing color which corresponds to the color represented by the color image data and which is positioned inside of the second gamut; and image recording means for recording, on the basis of the control signal, the color represented by the control signal on the image output medium, to thereby record a color image corresponding to the original color image on the image output medium.

Claim 21

The color image forming apparatus as claimed in claim 18, wherein said color-compression means selectively color-compresses the color represented by the color image data with a color-compression degree, which is determined on the basis of the color-compression parameter of the original color image, to thereby produce the replacing color image data.

Claim 22

A color image forming apparatus for obtaining a color image data representing each color of an original color image formed on an image input medium and forming on an image output medium a color image corresponding to the original color image, the image input medium having a first gamut and the image output medium having a second gamut, the first and second gamuts being defined as reproducible ranges of the image input medium and the image output medium, said color image forming apparatus comprising: image input means for inputting a color image data of color of each picture element of the original color image, the color represented by the color image data being positioned inside of the first gamut; color distribution detecting means for detecting color distribution of the original color image to generate color distribution information of the original color image; storing means for storing plural groups of combination data, each group consisting of plural color data to be inputtable by said image input means and record signals to control recording means to record colors corresponding to the color data, colors represented by the color data being positioned inside of the first gamut and colors represented by the record signals being positioned in the second gamut, the plural groups of combination data being calculated with respect to plural color distribution data generatable by said color distribution detecting means, each of the record signals in each of the plural groups of combination data being calculated through selectively color-compressing the corresponding color data in such a manner as determined on the basis of the corresponding color distribution data; selecting means for selecting one of the plural groups of combination data in accordance with the color distribution information generated by said color distribution detecting means; color processing means for processing at least one record signal of the selected one group of combination data to thereby produce a control signal, the control signal representing color which corresponds to the color represented by the color image data and which is positioned inside of the second gamut; and image recording means for recording, on the basis of the control signal, the color represented by the control signal on the image output medium, to thereby record on the image output medium a color image corresponding to the original color image.

Claim 23

A color image forming apparatus for obtaining a color image data representing each color of an original color image formed on an image input medium and forming on an image output medium a color image corresponding to the original color image, the image input medium having a first gamut and the image output medium having a second gamut, the first and second gamuts being defined as reproducible ranges of the image input medium and the image output medium, said color image forming apparatus comprising: image input means for inputting a color image data of color of each picture element of the original color image, the color represented by the color image data being positioned inside of the first gamut; color distribution detecting means for detecting color distribution of the original color image to generate color distribution information of the original color image; storing means for storing plural groups of combination data, each group consisting of plural color data to be inputtable by said image input means and record signals to control recording means to record colors corresponding to the color data, colors represented by the color data being positioned inside of the first gamut and colors represented by the record signals being positioned in the second gamut, the plural groups of combination data being calculated with respect to plural color distribution data generatable by said color distribution detecting means, each of the record signals in each of the plural groups of combination data being calculated through selectively color-compressing the corresponding color data in such a manner as determined on the basis of the corresponding color distribution data; selecting means for selecting one of the plural groups of combination data in accordance with the color distribution information generated by said color distribution detecting means; color processing means for processing at least one record signal of the selected one group of combination data to thereby produce a control signal, the control signal representing color which corresponds to the color represented by the color image data and which is positioned inside of the second gamut; and image recording means for recording, on the basis of the control signal, the color represented by the control signal on the image output medium, to thereby record on the image output medium a color image corresponding to the original color image.

Claim 24

The color image forming apparatus as claimed in claim 20, wherein said color processing means interpolatively calculates the control signal based on at least two record signals of the selected one group of combination data.

Claim 25

The color image forming apparatus as claimed in claim 19, wherein each of the record signals of each of the plural groups of the combination data is calculated through selectively color-compressing each of the plurality of color data in such a manner that such a color data as having a color-distribution-dependent relationship with the second gamut may be color-compressed into a replacing color data, the color-distribution-dependent relationship being determined on the basis of the corresponding color distribution data and through calculating the record signal based on the color data in the case where the color data is not color-compressed and calculating the record signal based on the replacing color data in the case where the color data is color-compressed into the replacing color data.

Claim 26

The color image forming apparatus as claimed in claim 22, wherein the record signals of each of the groups of the combination data are calculated through selectively color-compressing the color data with a color-compression degree, which is determined on the basis of the corresponding color distribution data, to generate the replacing color data.

Claim 27

The color image forming apparatus for obtaining a color image data, representing each color of an original color image formed on an image input medium and forming on an image output medium a color image corresponding to the original color image, the image input medium and the image output medium having first and second gamuts, respectively, the first and second gamuts being defined as reproducible ranges of the image input medium and the image output medium, said color image forming apparatus comprising: image input means for inputting a color image data representative of color of each picture element of the original color image, the color of each picture element thus represented by the color image data being positioned inside of the first gamut; color distribution detecting means for detecting color distribution of the original color image to generate color distribution information of the original color image; control signal producing means for producing a control signal on the basis of the color image data, the control signal having a value corresponding to that calculated through color-compression transformation of the color image data, the color-compression transformation being determined on the basis of the color distribution information of the original color image, color represented by the control signal corresponding to the color of each picture element of the original color image and being positioned inside of the second gamut; and image recording means for recording, on the basis of the control signal, the color represented by the control signal on the image output medium, to thereby record on the image output medium a color image corresponding to the original color image.

Claim 28

The color image forming apparatus for obtaining a color image data, representing each color of an original color image formed on an image input medium and forming on an image output medium a color image corresponding to the original color image, the image input medium and the image output medium having first and second gamuts, respectively, the first and second gamuts being defined as reproducible ranges of the image input medium and the image output medium, said color image forming apparatus comprising: image input means for inputting a color image data representative of color of each picture element of the original color image, the color of each picture element thus represented by the color image data being positioned inside of the first gamut; color distribution detecting means for detecting color distribution of the original color image to generate color distribution information of the original color image; control signal producing means for producing a control signal on the basis of the color image data, the control signal having a value corresponding to that calculated through color-compression transformation of the color image data, the color-compression transformation being determined on the basis of the color distribution information of the original color image, color represented by the control signal corresponding to the color of each picture element of the original color image and being positioned inside of the second gamut; and image recording means for recording, on the basis of the control signal, the color represented by the control signal on the image output medium, to thereby record on the image output medium a color image corresponding to the original color image.