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1.发明公开
公开(公告)号：EP0721279A3
公开(公告)日：1998-05-20
申请号：EP96300071
申请日：1996-01-03
Applicant: XEROX CORP
Inventor： CURRY DOUGLAS N
CPC classification number: H04N1/4078 , H04N1/4058
Abstract: A printing device (10) is commanded to print a reference set of intensity values from almost white or highlight regions through almost dark or shadow regions. A measuring device (12) measures the actual outputted printer intensity levels from the printing device (10). An interpolator (14) interpolates the printer intensity levels into a best fit smooth curve plotted against the reference set of intensity levels which produces a non-linear function. A mapping means and converter (24a, 24b) calculate a set of fractional intensity values and densities which produce a linear function when mapped with the printer intensity levels. A dot area parameter calculator (28) calculates a set of dot parameters defining a configuration of a halftone dot required to fill an area within the halftone cell corresponding to each intensity level. For each position of each halftone cell, a measurement processor (30) determines a distance between a current scan position (a,b) and a nearest edge defined by the dot parameters. A gray value calculator (50) calculates a gray value for the current scan position based on the distance and angle to the nearest edge of the dot. The halftone dot is completed when a gray value is calculated for each position within the halftone cell. The gray values are stored in a look-up table (26). When a new image is to be printed, the intensity values are input (54) and the scan position is indexed (52) through all available scan positions to generate corresponding addresses in the look-up table (26), causing the corresponding gray values to be output serially in order for use by a laser diode controller (56) of a laser printer or analogous controllers in other types of printers.
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公开(公告)号：DE69736797D1
公开(公告)日：2006-11-23
申请号：DE69736797
申请日：1997-10-30
Applicant: XEROX CORP
Inventor： CURRY DOUGLAS N
Abstract: A method and apparatus for halftoning image data using a location's fractional component to adjust edge data indicating location and orientation of an edge are described herein. The apparatus can be implemented in a hyperacuity printing system that includes a halftoner (20) which converts pixel intensity values into multi-bit gray values which drive a laser diode (62). The halftoner (20) includes a halftoner memory (22), a phase error look-up table (50), and a modulator (60). The halftoner memory (22) stores a pregenerated halftone dot pattern as a plurality of halftone dot planes or cells (24), each representing an intensity value. The halftoner memory (22) is addressed by the integer portion of a screen coordinate (x,y) and the intensity value, and outputs spatial coordinates (r, &thetas;) to an edge of the halftone dot nearest the screen coordinate. The fractional portion (xFRACT, yFRACT) of the screen coordinate (x,y) is combined with the outputted spatial coordinates (r,&thetas;) to provide corrected coordinates (rc,&thetas;). The corrected coordinates (rc,&thetas;) address a modulator drive function (56) which generates the multi-bit gray value used to drive the modulator (60). By combining the fractional portion of the screen coordinates with the halftoner memory data, automoire is corrected, and marks are rendered more accurately.
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公开(公告)号：DE69919115T2
公开(公告)日：2004-12-09
申请号：DE69919115
申请日：1999-12-16
Applicant: XEROX CORP
Inventor： CURRY DOUGLAS N
Abstract: A compression and decompression system and process for optimally compressing and decompressing multibit per pixel image regions based on the type of data contained in the image region, e.g., whether the image region contains continuous tone data, including data to be halftoned, or non-continuous tone data, including antialiased text and lineart data. Segmented bytemap data blocks are processed to provide both low spatial resolution continuous tone data and high spatial resolution non-continuous tone data. However, the high spatial resolution non-continuous tone data is generated by quantizing and packing the high resolution bytes across an edge and discarding the high resolution bytes along the edge, i.e., the multibit data is discarded only in directions parallel to the edges of marks to be rendered in the image data. Additional information indicating the directions of the edges in the image data are stored to aid in decompression. Subsequently, during decompression, the non-continuous tone data is decompressed into a high spatial resolution bytemap by unpacking the high resolution across the edges and inferring the high resolution along the edges. The low spatial resolution continuous tone data are processed to provide a low spatial resolution continuous tone data bytemap. As a result of this compression and decompression method, the amount of memory necessary to store the non-continuous tone data is reduced to a quarter of the memory necessary to store a conventional high spatial resolution bytemap.
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公开(公告)号：DE69526559T2
公开(公告)日：2002-08-22
申请号：DE69526559
申请日：1995-11-08
Applicant: XEROX CORP
Inventor： CURRY DOUGLAS N
IPC: H04N1/405
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公开(公告)号：DE69516456D1
公开(公告)日：2000-05-31
申请号：DE69516456
申请日：1995-06-02
Applicant: XEROX CORP
Inventor： CURRY DOUGLAS N
Abstract: Disclosed is a hyperacuity printing system (50) for rendering halftoned image data on a recording medium (14 ; Fig. 1). The printing system includes a data source (51) for supplying grayscale input image data and halftoning circuitry (70) (Fig.27) for receiving the grayscale input image data from the data source and transforming the grayscale input image data into multi-bit value output data. The halftoning circuitry (70) includes a look-up table for providing the multi-bit value output data where the multi-bit value output data define halftone dots, the halftone dots being arranged in the look-up table as a continuum from a lowest density value to a highest density value corresponding to the grayscale input image data, the halftone dots having a reference which is a predetermined position from a defined origin in the look-up table. Further included in the printing system is addressing circuitry providing a first set of address lines and a second set of address lines defining a screen stored in the memory, the first set of address lines and the second set of address lines providing x and y address values defined by a desired screen angle. The addressing circuitry includes rotation circuitry for modifying the x and y address values thereby rotating the halftone dots, resulting in rotated halftone dots. The addressing circuitry also includes shifting circuitry for modifying the x and y address values thereby shifting the reference point of the halftone dots away from the predetermined position from the defined origin in the look-up table, the shifting and the rotating occurring while the halftone dots are being read from the look-up table. Finally there is a modulating device for receiving the multi-bit value output data from the halftoning circuitry and converting the multi-bit value output data into a form which can be directly utilized by a writing device for writing the multi-bit value output data onto the recording medium.
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Patent Agency Ranking
公开(公告)号：DE69326646D1
公开(公告)日：1999-11-11
申请号：DE69326646
申请日：1993-07-19
Applicant: XEROX CORP
Inventor： CURRY DOUGLAS N
IPC: G02B26/10 , B41J2/44 , B41J2/47 , B41J2/485 , G06K15/12 , H04N1/04 , H04N1/113 , H04N1/12 , H04N1/19 , H04N1/193 , H04N1/23 , H04N1/40
Abstract: A method and apparatus is described for controlling the contrast, pitch grating of a composite light intensity profile and phase shifting of a spatial location at which the composite light intensity profile crosses a xerographic threshold in a two dimensional high addressability printer operating in an overscan mode. The contrast, pitch grating and phase shifting are dependent on at least one of a predetermined amount of overlap, an exposure profile and an intensity value of each of the plurality of laser beam spots (100,102,104,106,108) formed on the photosensitive medium of a two dimensional high addressability printer.
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公开(公告)号：DE69321903D1
公开(公告)日：1998-12-10
申请号：DE69321903
申请日：1993-08-18
Applicant: XEROX CORP
Inventor： CURRY DOUGLAS N
Abstract: An image enhancement method in which low-resolution bitmapped images may be enhanced and converted into gray images for printing on high-addressability printing and display systems. The method uses template (94) matching to determine a rendering goal, and converts the bitmap pixel into a numerical, multiple-bit-per-pixel sampled value (96) that is independent of the system it may ultimately be printed on. Unlike previous template matching methods which determined an enhanced pixel pattern output which was sent directly to the photoreceptor of a specific printer, the sampled data value of the present invention will require processing by the printer for its own particular characteristics before being sent to the photoreceptor. The sample data value may be sent directly to a printer imaging processor or stored via a network.
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公开(公告)号：CA2097956C
公开(公告)日：1998-08-18
申请号：CA2097956
申请日：1993-06-08
Applicant: XEROX CORP
Inventor： CURRY DOUGLAS N
IPC: B41J2/525 , B41J2/44 , G02B26/10 , G06K15/12 , H04N1/047 , H04N1/113 , H04N1/12 , H04N1/191 , B41J2/47
Abstract: An apparatus and method for providing accurate layer registration for multiple layer electronic printing systems discloses a means and a method of reducing the positional scan-to-scan error in a multiple layer electronic printing systems, typically multi-bearm laser raster output scanners, in which accurate layer registration is critical. The method comprises determination of a time delay between page sync signal and start-of-scan signal, using this delay to determine delay dependent offset factor called the phase registration parameter, and correctively mapping image data to proper output channels based on the phase registration parameter and the laser number. The phase registration parameter must be determined at the beginning of each scan layer and the offset factors must be re-adjusted based on the new phase delay.
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公开(公告)号：CA2128859C
公开(公告)日：1997-12-30
申请号：CA2128859
申请日：1994-07-26
Applicant: XEROX CORP
Inventor： CURRY DOUGLAS N
Abstract: A hyperacuity printing system for rendering halftoned image data on a recording medium. The system includes comprising a data source for supplying grayscale input image data and a writing device for writing grayscale output image data onto the recording medium. Also included is halftoning circuitry for transforming the grayscale input image data into the grayscale output image data, the halftoning circuitry including a look-up table for providing the grayscale output image data described as halftone dots arranged as a continuum from a lowest intensity value to a highest intensity value of the grayscale input image data. Finally, included is a modulating device coupled between the halftoning circuitry and the writing device for converting the grayscale output image data from the halftoning circuitry into a form which can be utilized by the writing device.
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公开(公告)号：DE69308239T2
公开(公告)日：1997-08-07
申请号：DE69308239
申请日：1993-06-10
Applicant: XEROX CORP
Inventor： THORNTON ROBERT L , CURRY DOUGLAS N
Abstract: A laser recorder for recording images on a substrate in response to a video signal (36) having a frequency which defines a pixel time (during which a single pixel is imaged) includes a duty cycle modulating digital to analog (D/A) converter (32) which outputs a variable duty cycle high frequency signal, based upon an intensity controlling N-bit input (34), to a power controller (26) which then controls the intensity of a light beam output by a laser based upon the variable duty cycle high frequency signal. The duty cycle modulating D/A converter outputs a high frequency variable duty cycle bitstream including a repeating cycle of fixed amplitude pulses, a total duration of all of the pulses in each cycle varying based upon the N-bit input signal. The high frequency of the variable duty cycle is sufficiently high so that the cycle of fixed amplitude pulses repeats multiple times within each pixel time, so that the intensity level with which pixels are formed on a substrate varies based upon the number of pulses output during each pixel time and the total duration of all pulses in each cycle. Preferably, the laser, power controller, and duty cycle modulating D/A converter are formed in a common semiconductive substrate. A detector (24) for detecting the intensity of light output by the laser is also preferably formed in the common semiconductive substrate, and provides feedback to the power controller. In a preferred embodiment, the duty cycle modulating D/A converter varies the total duration of the fixed amplitude pulse within a cycle by varying a number of fixed amplitude, fixed width pulses output during each cycle based upon the N-bit input signal.
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