US5657137A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Color digital halftoning using black and secondary color replacement
Assignee: Hewlett Packard Development Co LP
•
Filing: 1995-05-10
•
Granted: 1997-08-12
•
Expires: 2015-05-10
Abstract
Abstract This system selectively enables a printer to deposit primary or black color dots at pixel locations on a sheet to produce a color image--in such a way as to increase the overall number of dots used in the image, thereby minimizing contrast between dots on the sheet and adjacent areas and so providing a better simulation of a continuous-tone image. The result is print quality often near that of error diffusion, usually better than any dither technique, but with the greater speed of a dither technique. The system includes a memory for storing a first color vector for each pixel in the image, respectively, and a processor coupled to the memory for determining a second color vector from each of the first vectors, respectively. The processor accomplishes this determination by replacing a fraction of the black color component of the first vector with primary colors. Preferably the processor also removes from the first color vector a quantity of white, in conjunction with the black replacement; in this case the processor sets the fraction of the black component to a value between zero and one inclusive, depending on the quantity of white that is available, in the first color vector, for removal. Preferably the fraction is the smaller of (1) the quantity of black present and (2) a certain fraction of the quantity of white available for removal. Analogously a fraction of the secondary color component of a color vector is replaced with primary colors.
Inventors
- 👤 Alexander Perumal, Jr.
- 👤 Paul H. Dillinger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 09:50
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/46; H04N1/56; H04N1/60; H04N1/6016; H04N1/6022; H04N1/52
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
116 words
A system for selectively enabling a printer to deposit primary or black color dots at each of a plurality of pixel locations on a sheet in a binary manner to produce a binary simulation of a continuous-tone color image, said system comprising: memory means for storing a first color vector, for each pixel in the color image respectively; processor means, coupled to said memory means, for decreasing contrast at each pixel to improve the binary simulation of a continuous-tone color image; said processor means comprising means for determining a second color vector from each said first color vector, respectively, by replacing a fraction of the black color component of said first color vector with primary colors.
Claim 2
Independent Claim
116 words
A system for selectively enabling a printer to deposit primary or black color dots at each of a plurality of pixel locations on a sheet in a binary manner to produce a binary simulation of a continuous-tone color image, said system comprising: memory means for storing a first color vector, for each pixel in the color image respectively; processor means, coupled to said memory means, for decreasing contrast at each pixel to improve the binary simulation of a continuous-tone color image; said processor means comprising means for determining a second color vector from each said first color vector, respectively, by replacing a fraction of the black color component of said first color vector with primary colors.
Claim 3
Dependent Claim
24 words
The system of claim 1, further comprising: means for replacing a fraction of secondary color component of said first color vector with primary colors.
Claim 4
Dependent Claim
63 words
The system of claim 1, further comprising: means for receiving information about a desired color image and in response thereto for generating said color vector for each pixel position wherein the processor means comprise means for expressing the desired color image information in the form of a hue-plus-gray color vector for each pixel position, if the information is not already in that form.
Claim 5
Dependent Claim
23 words
The system of claim 1, further comprising: means for applying the second color vector to operate the printer for producing said color image.
Claim 6
Dependent Claim
35 words
The system of claim 4, wherein: the applying means comprise means for dithering the second color vector to select a single color component of a third color vector for printing at each pixel position, respectively.
Claim 7
Dependent Claim
28 words
The system of claim 1, wherein: the printer uses as chromatic primary colors magenta, cyan and yellow; and the printer uses as secondary colors blue, green and red.
Claim 8
Dependent Claim
19 words
The system of claim 6, wherein: the printer prints the secondary colors as combinations of the chromatic primary colors.
Claim 9
Independent Claim
145 words
A system for selectively enabling a printer to deposit primary or black color dots at each of a plurality of pixel locations on a sheet to produce a color image, said system comprising: memory means for storing a first color vector, for each pixel in the color image respectively; and processor means coupled to said memory means for determining a second color vector from each said first color vector, respectively, by replacing a fraction of the black color component of said first color vector with primary colors; and wherein the processor means comprise: means for removing from the first color vector a quantity of white, in conjunction with said black replacement; and means for setting said fraction of the black component to a value between zero and one inclusive, depending upon the quantity of white that is available, in the first color vector, for removal.
Claim 10
Independent Claim
145 words
A system for selectively enabling a printer to deposit primary or black color dots at each of a plurality of pixel locations on a sheet to produce a color image, said system comprising: memory means for storing a first color vector, for each pixel in the color image respectively; and processor means coupled to said memory means for determining a second color vector from each said first color vector, respectively, by replacing a fraction of the black color component of said first color vector with primary colors; and wherein the processor means comprise: means for removing from the first color vector a quantity of white, in conjunction with said black replacement; and means for setting said fraction of the black component to a value between zero and one inclusive, depending upon the quantity of white that is available, in the first color vector, for removal.
Claim 11
Dependent Claim
56 words
The system of claim 8, wherein: said setting means comprise means for establishing said fraction of the black component as the smaller of (1) the quantity of black that is present in the first color vector and (2) a specified fraction, between zero and one inclusive, of the quantity of white that is available for removal.
Claim 12
Dependent Claim
20 words
The system of claim 9, wherein: said establishing means use one-half as said specified fraction of the quantity of white.
Claim 13
Dependent Claim
26 words
The system of claim 9, wherein: said establishing means use 1/α as said specified fraction of the quantity of white, where α is greater than two.
Claim 14
Dependent Claim
25 words
The system of claim 9, wherein: said establishing means use 1/α as said specified fraction of the quantity of white, where α is roughly sixteen.
Claim 15
Dependent Claim
30 words
The system of claim 8, further comprising: means for replacing a fraction of secondary color component of said second color vector with primary colors, to form a third color vector.
Claim 16
Dependent Claim
87 words
The system of claim 13, wherein the processor means further comprise: means for removing from the second color vector an amount of white, in conjunction with said secondary/color component replacement; and wherein the processor means comprise means for using the size of the white component that remains available in the second color vector, after removal of said quantity of white from the first color vector in conjunction with black replacement, to set said fraction of the secondary color component to a value between zero and one inclusive.
Claim 17
Dependent Claim
85 words
The system of claim 14, wherein: said using means comprise means for defining said fraction of the secondary color component as the smaller of (1) the quantity of secondary color component that is present in the second color vector and (2) a certain fraction, between zero and one inclusive, of the quantity of white that remains available for removal from the second color vector, after removal of said specified fraction of the quantity of white from the first color vector in conjunction with black replacement.
Claim 18
Dependent Claim
20 words
The system of claim 15, wherein: said defining means use one as said certain fraction of the quantity of white.
Claim 19
Dependent Claim
28 words
The system of claim 15, wherein: said white component size-using means use 1/β as said certain fraction of the quantity of white, where β is greater than one.
Claim 20
Dependent Claim
27 words
The system of claim 15, wherein: said white component size-using means use 1/β as said certain fraction of the quantity of white, where β is roughly eight.
Claim 21
Dependent Claim
23 words
The system of claim 13, further comprising: means for applying the third color vector to operate the printer for producing said color image.
Claim 22
Dependent Claim
35 words
The system of claim 19, wherein: the applying means comprise means for dithering the third color vector to select a single color component of the third color vector for printing at each pixel position, respectively.
Claim 23
Independent Claim
176 words
A system for selectively enabling a printer to deposit on a sheet, Cyan (C), Magenta (M), Yellow (Y) and Black (K) color dots at each of a plurality of pixel locations, in a binary manner to produce a binary simulation of a continuous-tone color image, said system comprising: memory means for storing a first array of color vectors for each pixel in the color image; processor means, coupled to said memory means, for decreasing contrast at each pixel to improve the binary simulation of a continuous-tone color image; said processor means comprising means for determining a second array of color vectors from said first array of color vectors by: (i) replacing the black color component of said first array with the primary colors cyan, magenta and yellow for each pixel location from said color vectors stored in said first array, and (ii) replacing the secondary color component red, green or blue of said first array with the primary colors cyan, magenta and yellow for each pixel location from said color vectors stored in said first array.
Claim 24
Independent Claim
176 words
A system for selectively enabling a printer to deposit on a sheet, Cyan (C), Magenta (M), Yellow (Y) and Black (K) color dots at each of a plurality of pixel locations, in a binary manner to produce a binary simulation of a continuous-tone color image, said system comprising: memory means for storing a first array of color vectors for each pixel in the color image; processor means, coupled to said memory means, for decreasing contrast at each pixel to improve the binary simulation of a continuous-tone color image; said processor means comprising means for determining a second array of color vectors from said first array of color vectors by: (i) replacing the black color component of said first array with the primary colors cyan, magenta and yellow for each pixel location from said color vectors stored in said first array, and (ii) replacing the secondary color component red, green or blue of said first array with the primary colors cyan, magenta and yellow for each pixel location from said color vectors stored in said first array.
References Cited (Backward Citations)
US4413275A
Cited
US4458265A
Cited
US4446470A
Cited
US4477833A
Cited
US4573071A
Cited
US4614967A
Cited
US4682216A
Cited
DE3447682A1
Cited
US4656505A
Cited
US4733256A
Cited
US4956703A
Cited
US4962421A
Cited
US5070413A
Cited
US5243443A
Cited
US5276535A
Cited
US5428377A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-08-11 | 2001-02-10 | 2001-08-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-08-11 | 2005-02-10 | 2005-08-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-08-11 | 2009-02-10 | 2009-08-12 | $7700.00 | Window Closed / Lapsed |