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EP0308858A2
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Method of correcting color image data for obtaining proof image
Assignee: Dainippon Screen Manufacturing Co Ltd
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Filing: 1988-09-20
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Granted: —
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Expires: 2008-09-20
Abstract
Abstract Color image data (Y, M, C and K) are subjected to a first correction for a first additivity failure caused by mixture of primary chromatic components (Y, M and C) in a first processor (S1) and further to a second correction for a second additivity failure caused by mixture of respective primary chromatic components (Y, M and C) and achromatic component (k) in a second processor (S2), thereby to obtain color image data (Y5, M5 and C5) by which a color film approximating printed matter is reproduced. Functions for compensating the additivity failures are set on the basis of actual densities of the printed matter and the color film.
Inventors
- 👤 Kimihiro Dainippon Screen Mfg. Co Ltd. Nakatsuka
- 👤 Fumihiro Dainippon Screen Mfg. Co Ltd. Hatayama
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 20:09
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/46; H04N1/56; H04N1/60; H04N1/6011
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
200 words
A method of correcting color image data to obtain a proof image on an image reproduction means for previewing a printed image produced accoridng to said color image data, said method comprising the steps of: (a) preparing a reference color image data, (b) printing a first reproduced image with color inks according to said reference color image data, (c) producing a second reproduced image on said image reproduction means accoridng to said reference color image data, said image reproduction means having a color mixture characteristic different from a color mixture characteristic of said color inks, (d) comparing said first and second reproduced images with each other to determine the difference between respective color mixture characteristics of said color inks and said image reproduction means, (e) determining a correction rule for compensating said difference, (f) reading an image of an original with a color image reader to obtain first color image data consisting of chromatic and achromatic components, and (g) correcting said first color image data using said correction rule to obtain second color image data consisting of chromatic components to obtain said proof image approximating said printed image which is reproduced on the basis of said first color image data.
Claim 2
Independent Claim
200 words
A method of correcting color image data to obtain a proof image on an image reproduction means for previewing a printed image produced accoridng to said color image data, said method comprising the steps of: (a) preparing a reference color image data, (b) printing a first reproduced image with color inks according to said reference color image data, (c) producing a second reproduced image on said image reproduction means accoridng to said reference color image data, said image reproduction means having a color mixture characteristic different from a color mixture characteristic of said color inks, (d) comparing said first and second reproduced images with each other to determine the difference between respective color mixture characteristics of said color inks and said image reproduction means, (e) determining a correction rule for compensating said difference, (f) reading an image of an original with a color image reader to obtain first color image data consisting of chromatic and achromatic components, and (g) correcting said first color image data using said correction rule to obtain second color image data consisting of chromatic components to obtain said proof image approximating said printed image which is reproduced on the basis of said first color image data.
Claim 3
Dependent Claim
78 words
A method in accordance with claim 1, wherein said step (g) includes the steps of: (g-1) correcting said chromatic components of said first color image data into intermediate color image data consisting of chromatic components, thereby to compensate a first addivity failure caused by mixture of chromatic components, and (g-2) combining chromatic components included in said intermediate color image data with said achromatic component included in said first color image data, to obtain said second color image data.
Claim 4
Dependent Claim
35 words
A method in accordance with claim 2, wherein said correction rule includes a first additivity failure function for compensating said first additivity failure, and said step (g-1) is conducted using said first additivity failure funciton.
Claim 5
Dependent Claim
38 words
A method in accordance with claim 3, wherein said difference is found for a plurality of colors in said step (d), and said first additivity failure function is obtained through an interpolation of said difference for said colors.
Claim 6
Dependent Claim
132 words
A method in accordance with claim 4, wherein said step (g-2) further includes the steps of: (g-2a) converting said chromatic components of said intermediate color image data into a first data consisting of chromatic components using an inverse function of a second additivity failure function, said second additivity failure function being so determined as to compensate a second additivity failure caused by mixture of the chromatic components and achromatic component, (g-2b) converting said achromatic component of said first color image data into second data consisting of achromatic color component using said inverse function, (g-2c) adding said second data to respective chromatic components of said first data to obtain third data consisting of chromatic components, and (g-2d) converting said third data into said second color image data using said second additivity failure function.
Claim 7
Dependent Claim
49 words
A method in accordance with claim 5, wherein said reference color image data expresses color image data expressing an image of a chromatic color scale, and said first additivity failure function is determined by comparison of said first and second reproduced images obtained through said reference color image data.
Claim 8
Dependent Claim
39 words
A method in accordance with claim 6, wherein said reference color image data is obtained by the step of reading respective colors of color patches with said color image reader, where different colors are provided on said color patches.
Claim 9
Dependent Claim
139 words
A method in accordance with claim 6, wherein said second additivity failure function is determined by the steps of: (h-1) preparing a reference gray image data having chromatic components and an achromatic component whose combination expresses an image of a gray scale, (h-2) producing chromatic blocks according to said chromatic components of said reference gray image data, (h-3) producing an achromatic block according to said achromatic component of said reference gray image data, (h-4) printing a first gray image with said chromatic blocks or said achromatic block, (h-5) printing a second gray image with said chromatic blocks and said achromatic block, (h-6) comparing respective densities of said first and second gray images to determine a relation between said respective densities, and (h-7) determining said second additivity failure function on the basis of said relation found in said step (h-6).
Claim 10
Independent Claim
199 words
A method of determining a correction rule used to compensate an additivity failure caused by a mixture of chromatic components and an achromatic component included in a color image data, where said additivity failure expresses a discrepancy between respective densities of a first reproduced image printed with color inks and a second reproduced image reproduced with an image reproduction means other than color inks both of which are obtained according to said color image data, said method comprising the steps of: (a) preparing a reference gray image data having chromatic components and an achromatic component whose combination expresses an image of a gray scale, (b) producing chromatic blocks according to said chromatic components of said reference gray image data, (c) producing an achromatic block according to said achromatic component of said reference gray image data, (d) printing a first gray image with said chromatic blocks or said achromatic block, (e) printing a second gray image with said chromatic blocks and said achromatic block, (f) comparing respective densities of said first and second gray images to determine a relation between said respective densities, and (g) determining said correction rule on the basis of said relation determined in said step (f).
Claim 11
Independent Claim
199 words
A method of determining a correction rule used to compensate an additivity failure caused by a mixture of chromatic components and an achromatic component included in a color image data, where said additivity failure expresses a discrepancy between respective densities of a first reproduced image printed with color inks and a second reproduced image reproduced with an image reproduction means other than color inks both of which are obtained according to said color image data, said method comprising the steps of: (a) preparing a reference gray image data having chromatic components and an achromatic component whose combination expresses an image of a gray scale, (b) producing chromatic blocks according to said chromatic components of said reference gray image data, (c) producing an achromatic block according to said achromatic component of said reference gray image data, (d) printing a first gray image with said chromatic blocks or said achromatic block, (e) printing a second gray image with said chromatic blocks and said achromatic block, (f) comparing respective densities of said first and second gray images to determine a relation between said respective densities, and (g) determining said correction rule on the basis of said relation determined in said step (f).
References Cited (Backward Citations)
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