Patent EP0372826A2 successfully refreshed from Google Patents.
EP0372826A2
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EP
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Method and system for enhancing the quality of both color and black and white images produced by ink jet printers
Assignee: HP Inc
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Filing: 1989-11-30
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Granted: —
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Expires: 2009-11-30
Abstract
Abstract A method for reducing "grainyness" or color contrast in color imaging systems and simultaneously reducing or eliminating paper cockleing of media printed by ink jet printing. The method involves determining the maximum allowable ink print density necessary to reduce or eliminate paper cockleing in the printed media and then providing tight control of the selection of gray scale ink drop count and associated dye loading in relation to this maximum allowable print density. Using this method, pixels are selected and printed in such a manner as to maximize the uniformity of ink distribution on the printed media. This method will work using either a variable drop size or a fixed drop size with variable dye loadings. It will also work with most error diffusion or dithering schemes presently used and available in the image processing arts.
Inventors
- 👤 C. S. Chan
- 👤 Terry M. Nelson
- 👤 James G. Bearss
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 13:03
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/46; H04N1/52; G; G06; G06K; G06K15/00; G06K15/02; G06K15/10; G06K15/102; H04N1/40; H04N1/40087; B; B41; B41J; B41J2/00; B41J2/005; B41J2/01; B41J2/21; B41J2/2121; B41J2/2128; G06K2215/00; G06K2215/0082; G06K2215/0094
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
132 words
A method for converting scanned image information to a hardcopy printout which comprises ejecting ink onto a print medium in a pixel address sequence thereon controlled by the value of gray scale digital numbers to which said image information is assigned, said method including the steps of: a. selecting a print area on a print medium for receiving a predetermined maximum ejected quantity of ink, V max , b. converting scanned image data to a gray scale digital number corresponding to ink volumes which do not exceed V max when introduced into said print area, and c. diffusing into areas surrounding said print area a quantity of ink equal to the difference between an actual gray scale number representative of said scanned image and said gray scale digital number in (b) above.
Claim 2
Independent Claim
132 words
A method for converting scanned image information to a hardcopy printout which comprises ejecting ink onto a print medium in a pixel address sequence thereon controlled by the value of gray scale digital numbers to which said image information is assigned, said method including the steps of: a. selecting a print area on a print medium for receiving a predetermined maximum ejected quantity of ink, V max , b. converting scanned image data to a gray scale digital number corresponding to ink volumes which do not exceed V max when introduced into said print area, and c. diffusing into areas surrounding said print area a quantity of ink equal to the difference between an actual gray scale number representative of said scanned image and said gray scale digital number in (b) above.
Claim 3
Dependent Claim
81 words
The method defined in claim 1 which also includes: a. selecting a maximum allowable ink drop volume, V max , to be received by said selected print area within a chosen print medium, b. scanning an image to generate digital data representative thereof, c. converting said digital data to gray scale digital information, and d. processing said digital information in such a manner as to prevent the volume of an ejected ink drop from a printhead from exceeding V max .
Claim 4
Independent Claim
45 words
The method defined in claims 2 or 3 which also includes: a. providing a matrix of pixels consisting of a predetermined number of sub-pixels, and b. selecting for ink printing chosen sub-pixels based upon the value of individual digits within said gray scale digital information.
Claim 5
Independent Claim
51 words
The method defined in claims 2 or 3 which also includes scanning rows and columns of a matrix of pixels during said printing operation, and rotating the address of sub-pixels within each successively addressed pixel as a function of the value of said individual digits within said gray scale digital information.
Claim 6
Independent Claim
36 words
The method defined in claims 3 or 4 wherein said matrix of pixels comprises rows representative of high, medium and low ink dye loadings and columns corresponding to black, cyan, magenta and yellow colors of ink.
Claim 7
Dependent Claim
115 words
An image conversion system for converting scanned image information to a hardcopy printout from an ink printer and wherein said scanned image information is initially converted to cyan, yellow, magenta and black pixel information, characterized in that error diffusion and pixel assignment gray scaling means are connected in said image conversion system for receiving said pixel information and for driving an ink printer or storage file therefor, said gray scaling means providing an input control signal to a color printer for causing said color printer to eject ink onto a print medium in a pixel address sequence thereon controlled by the value of gray scale digital numbers to which said scanned image information is assigned.
Claim 8
Dependent Claim
115 words
An image conversion system for converting scanned image information to a hardcopy printout from an ink printer and wherein said scanned image information is initially converted to cyan, yellow, magenta and black pixel information, characterized in that error diffusion and pixel assignment gray scaling means are connected in said image conversion system for receiving said pixel information and for driving an ink printer or storage file therefor, said gray scaling means providing an input control signal to a color printer for causing said color printer to eject ink onto a print medium in a pixel address sequence thereon controlled by the value of gray scale digital numbers to which said scanned image information is assigned.
Claim 9
Dependent Claim
67 words
The system defined in claim 6 which also includes: a. means for selecting a print area on a print medium for receiving a predetermined maximum ejected quantity of ink, V max , and b. means connected to said selecting means for converting scanned image data to a gray scale digital number corresponding to ink volumes which do not exceed V max when introduced into said print area.
Claim 10
Independent Claim
72 words
The system defined in claims 6 or 7 which also includes: a. means for scanning an image to generate digital data representative thereof, b. means connected to said scanning means for converting said digital data to gray scale digital informtion, and c. means connected to said converting means for processing said digital information in such a manner as to prevent the volume of an ejected ink drop from exceeding V max .
Claim 11
Dependent Claim
72 words
The system defined in claim 6 which also includes: a. means within said image conversion system for generating gray scale digital data representative of said scanned image information, and b. means connected to said generating means in (a) above for providing a matrix of pixels consisting of a predetermined number of sub-pixels, and for selecting chosen sub-pixels for printing based upon the value of individual digits within said gray scale digital numbers.
Claim 12
Dependent Claim
52 words
The system defined in claim 9 which also includes means for scanning rows and columns of said matrix of pixels during said printing operation and for rotating the address of sub-pixels within each successively addressed pixel as a function of the value of said individual digits within said gray scale digital data.
Claim 13
Dependent Claim
36 words
The system defined in claim 10 wherein said matrix of pixels comprises rows representative of high, medium and low dye loadings for said ink and columns corresponding to black, cyan, magenta and yellow colors of ink.
Claim 14
Dependent Claim
200 words
A method for simultaneously minimizing color contrast and paper cockleing during ink jet printing which comprises the steps of: a. scanning an image to provide pixel information values of one or more colors existent in said image, b. providing a plurality of different gray scale entry level numbers representative of different available combinations of ink drop count numbers and their associated dye loadings for each color and within a corresponding plurality of different levels of a chosen gray table, c. establishing a predetermined maximum allowable drop volume of ink, V max , which may be received on a printed area with negligible paper cockleing, and d. selecting for printing the maximum drop count number for each of said colors within said available combinations of drop count numbers so that the sum of all drop count numbers does not exceed V max , whereby more drops having a lower gray scale value and lower dye loading may be distributed over a larger pixel area or super pixel area to minimize color contrast and grainyness therein. 13. The process defined in claim 12 wherein one or more colors are selected from the group of colors consisting of cyan, yellow, magenta and black.
References Cited (Backward Citations)
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