公开(公告)号：DE69628800T2

公开(公告)日：2004-02-05

申请号：DE69628800

申请日：1996-11-14

Applicant: XEROX CORP

Inventor： HARRINGTON STEVEN J

IPC: B41J2/525 ,  G03G15/01 ,  H04N1/52 ,  H04N1/60

Abstract: An image processing system, and method, for a multicolor printer, including a halftone generator that converts contone separation signals to binary separation signals. Halftone screens are generated for each separation in accordance with the goal of avoiding overlapping whenever possible. Initially, the black separation is halftoned, generating a dot pattern with a number of ON (K) pixels and OFF pixels in accordance with the area density of the black separation. Next, a first color (MAGENTA) separation is halftoned, setting a number of the previous OFF pixels to ON. Then, if any white pixels remain, a second color (CYAN) separation is halftoned, setting a number of the previously OFF pixels to ON. If during the processing of the second and third separations, it is determined that no OFF pixels exist to be turned ON, a second layer of color is started, respectively superimposed over the first layer. A third color separation (YELLOW) is halftoned in reverse fill-in order, setting a number of the previous OFF pixels to ON. Each layer is started and arranged so that the additional colors forming the dot pattern are not placed on any black areas.

公开(公告)号：DE69819608D1

公开(公告)日：2003-12-18

申请号：DE69819608

申请日：1998-05-07

Applicant: XEROX CORP

Inventor： HARRINGTON STEVEN J ,  KLASSEN VICTOR R

IPC: H04N1/405 ,  H04N1/40

Abstract: In this proposal a method of multilevel halftoning is described that allows the definition of halftone patterns using more than two gray levels at a time. This feature can be employed to eliminate the texture contours produced when shades formed by a pattern of two levels blends into a shade formed by a single gray level. The method also gives control over the degree to which a given output gray level is used. This can be employed to limit ink coverage when certain levels require more ink to produce than do others. According to the method: initial pixel intensity ranges are obtained; the initial pixel intensity ranges are compared to at least two overlapping threshold arrays; and selection of enhanced pixel intensity levels are determined for halftone cells according to the comparison results of the initial pixel intensity ranges to at least two overlapping threshold arrays wherein the enhanced pixel intensity levels are a function of results from the comparison.

公开(公告)号：DE69628800D1

公开(公告)日：2003-07-31

申请号：DE69628800

申请日：1996-11-14

Applicant: XEROX CORP

Inventor： HARRINGTON STEVEN J

IPC: B41J2/525 ,  G03G15/01 ,  H04N1/52 ,  H04N1/60

Abstract: An image processing system, and method, for a multicolor printer, including a halftone generator that converts contone separation signals to binary separation signals. Halftone screens are generated for each separation in accordance with the goal of avoiding overlapping whenever possible. Initially, the black separation is halftoned, generating a dot pattern with a number of ON (K) pixels and OFF pixels in accordance with the area density of the black separation. Next, a first color (MAGENTA) separation is halftoned, setting a number of the previous OFF pixels to ON. Then, if any white pixels remain, a second color (CYAN) separation is halftoned, setting a number of the previously OFF pixels to ON. If during the processing of the second and third separations, it is determined that no OFF pixels exist to be turned ON, a second layer of color is started, respectively superimposed over the first layer. A third color separation (YELLOW) is halftoned in reverse fill-in order, setting a number of the previous OFF pixels to ON. Each layer is started and arranged so that the additional colors forming the dot pattern are not placed on any black areas.

公开(公告)号：DE69426367D1

公开(公告)日：2001-01-11

申请号：DE69426367

申请日：1994-03-22

Applicant: XEROX CORP

Inventor： HARRINGTON STEVEN J

IPC: B41J2/52 ,  G06F3/12 ,  G06T5/00 ,  H04N1/407 ,  H04N1/40

Abstract: A method for calibrating a printer determines a tone reproduction curve for the printer. A plurality of bands (12,16,20,24,28,32,36,40,44,48,52) of different accurate gray level standards and a corresponding number of smoothly increasing sequences (14,18,22,26,30,34,38,42,46,50,54) of gray level specifications for the printer are printed adjacent to one another. Adjacent bands and sequences are compared, and a point along each band where the band appears equal to the adjacent gray level specification sequence is determined. The points are interpolated and the interpolated values are used to form a tone reproduction curve for the printer. The tone reproduction curve, representing the correspondence between the gray level specification of the printer and the actual gray levels produced by the printer, can then be used to calibrate the printer. The calibrating method can also be used for color printers.

公开(公告)号：DE69327746T2

公开(公告)日：2000-08-31

申请号：DE69327746

申请日：1993-06-08

Applicant: XEROX CORP

Inventor： HARRINGTON STEVEN J ,  HSU LILLIAN-LIU ,  BONK LAWRENCE R ,  ZELL THOMAS B ,  CATAPANO DAVID A ,  KRIST PETER M ,  BRYANT RICHARD E ,  LEGG ERNEST L ,  ALLEN IRENE M ,  RULLI PAUL A

IPC: G06F3/12 ,  G06F11/267 ,  G06F17/21 ,  G06K15/00

公开(公告)号：DE69514596D1

公开(公告)日：2000-02-24

申请号：DE69514596

申请日：1995-08-24

Applicant: XEROX CORP

Inventor： HARRINGTON STEVEN J

IPC: G06T1/00 ,  H04N1/46 ,  H04N1/60

Abstract: Input device signals Rs, Gs, Bs generated by an image input terminal (4) are converted to colorimetric values Rc, Gc, Bc. The colorimetric values processed by an image processing unit (24) to generate address entries to a lookup table which stores a set of transform coefficients with which the Rc, Gc, Bc values may be processed to convert them to Cp,Mp,Yp,Kp colorant signals or any multi-dimensional output color space, which include but are not limited to CMYK or spectral data. Values which are not directly mapped from the table are determined using tetrahedral interpolation over a hexagonal lattice. The hexagonal lattice is formed by offsetting by a half unit every other row of one of its dimensions relative to another dimension. The offset provides closer packing of sample points that define more regular tetrahedrons to reduce relative interpolation errors. The packing also allows for easy lookup table access and simple tests to determine which tetrahedron contains a desired value.

公开(公告)号：DE69419463T2

公开(公告)日：1999-10-28

申请号：DE69419463

申请日：1994-08-05

Applicant: XEROX CORP

Inventor： HARRINGTON STEVEN J

IPC: B41J2/525 ,  H04N1/405 ,  H04N1/52 ,  H04N1/60

Abstract: Halftone screens are generated for each separation in accordance with the goal of avoiding overlapping whenever possible. Initially, the black separation (K) is halftoned, generating a dot with a number of ON pixels and OFF pixels in accordance with the area density of the black separation. Next, a first color separation (C) is halftoned, setting a number of the previous OFF pixels to ON. Then, if any white pixels remain, the second color separation (M) is halftoned, setting a number of the previously OFF pixels to ON. After the second color separation is halftoned, if any OFF pixels remain, the third color separation (Y) is halftoned, setting a number of the previous OFF pixels to ON. If during the processing of the second and third separations, it is determined that no OFF pixels exist to be turned ON, second and third layers of color is started, respectively superimposed over the first layer and then, if required, superimposed over the second layer. Each layer is started and arranged so that the additional colors forming the dot are not placed on any black areas.

公开(公告)号：DE69226409T2

公开(公告)日：1999-03-18

申请号：DE69226409

申请日：1992-09-11

Applicant: XEROX CORP

Inventor： HARRINGTON STEVEN J

IPC: B41J2/525 ,  B41J2/21 ,  H04N1/23 ,  H04N1/56 ,  H04N1/46

Abstract: A dense black image is formed by printing the black ink in combination with at least one other ink without resulting in thick, blurred figure edges. A bitmap of binary information is provided for each of a plurality of color separations, each bitmap indicating desired locations of ink spots for a color separation. Spots are eroded on the boundaries of black image areas (12) in the bitmap to form a modified black image bitmap (14). The modified black image bitmap (14) is printed in ink of at least one color other than black at the same time that the bitmaps for the color separations other than black are printed. The original black image bitmap (12) is then printed in black ink over the printed modified black image bitmap to yield a dense black image.

公开(公告)号：BR9701105A

公开(公告)日：1998-09-08

申请号：BR9701105

申请日：1997-02-27

Applicant: XEROX CORP

Inventor： HARRINGTON STEVEN J ,  BENNETT SCOTT A ,  MALTZ MARTIN S

IPC: G06T1/00 ,  G06T1/20 ,  G06T11/00 ,  H04N1/46 ,  H04N1/60 ,  H04N1/024

Abstract: A method and apparatus for blending pictorial and graphical look-up tables, in which the blended look-up table, addressable by image signals from both pictorial and graphical objects, produces printer signals which are a blend of the output of the pictorial and graphical look-up tables. For image signals that are inside the pictorial gamut of the printer, only the output of the pictorial look-up table is used in the blended look-up table. For image signals that are outside the pictorial gamut, a blend of the output of both pictorial and graphical look-up tables is used in the blended look-up table. To blend the tables, graphical and pictorial image signals are selected from the surface of the graphical and pictorial gamut which have the same hue and luminance as the desired image signal. Printer signals output by both the graphical and pictorial look-up tables are weighted in accordance with the proportions of graphical and pictorial character container in the desired image signal, determined from the difference in saturation between the desired image signal and the selected graphical and pictorial image signals. The weighted printer signals are added and mapped to the desired image signal, the mapping being stored in an image signal translator.

公开(公告)号：DE69032515D1

公开(公告)日：1998-09-03

申请号：DE69032515

申请日：1990-06-08

Applicant: XEROX CORP

Inventor： HARRINGTON STEVEN J

IPC: G09G5/36 ,  G06T11/40

Abstract: In a system having a frame buffer for generating an image wherein the image is defined as an outline having an interior described by the non-zero winding rule, the method of providing visual images along a scan direction comprises the steps of entering into the frame buffer predetermined direction codes (d. u etc.), determining points of intersection and points of adjacent location in the scan direction, and spatially offsetting direction codes in the scan direction for said points of intersection and points of adjacent location in the scan direction.