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    3.
    发明专利
    未知

    公开(公告)号：BR0101658B1

    公开(公告)日：2014-09-16

    申请号：BR0101658

    申请日：2001-05-02

    Applicant: XEROX CORP

    Inventor： MESTHA LINGAPPA K

    IPC: G01J3/46

    Abstract: A limited number of voltage measurements are received from a multiple illuminant color sensor at the direction of a color sensor controller. The received sensor voltages are normalized in accordance with a calibration look-up table. Next, the normalized sensor voltages are converted to reflectance values based on a correction look-up table. Then, a reconstruction look-up table is used to convert the reflectance values at a predetermined wavelength to reflectance values with a predetermined wavelength separation.

    5.
    发明专利
    未知

    公开(公告)号：DE69817709T2

    公开(公告)日：2004-03-11

    申请号：DE69817709

    申请日：1998-07-17

    Applicant: XEROX CORP

    Inventor： FOLKINS JEFFREY J ,  SHAHIN MICHAEL A ,  SMITH CRAIG A ,  PARISI MICHAEL A ,  MESTHA LINGAPPA K

    IPC: B41M3/14 ,  G03G21/04 ,  H04N1/00

    Abstract: A method comprising: providing a facility with at least one controlled access electronic printing machine; printing original documents with said controlled access electronic printing machine, wherein printed images formed thereby arise from marking materials containing at least one photoactive additive; equipping all uncontrolled access reprographic devices within said facility with a secure illumination source capable of exposing an object document with sufficient intensity to activate said photoactive additive; and illuminating said object document with said secure illumination source of said uncontrolled access reprographic device, wherein said object documents having original document images printed thereon cannot be copied or scanned in a normal copy or scan illumination interval.

    6.
    发明专利
    未知

    公开(公告)号：BR0203438B1

    公开(公告)日：2014-11-04

    申请号：BR0203438

    申请日：2002-08-29

    Applicant: XEROX CORP

    Inventor： MESTHA LINGAPPA K ,  DIANAT SOHAIL A

    IPC: G01J3/28 ,  G01J3/52 ,  G03G13/01

    Abstract: A spectral determination system, comprising a plurality of illuminants; at least one photodetector that detects light originating from the plurality of illuminants and reflected by a target; and a controller that: normalizes a plurality of illuminant sensor outputs obtained from the at least one photodetector, each illuminant sensor output indicating a reflectance value obtained from a target; obtains reference data from a reference database that correlates reference spectra with a corresponding plurality of normalized illuminant sensor outputs, the reference data including data in a neighborhood of each reflectance value; and determines a spectrum S based on the illuminant sensor outputs and the reference data, wherein the determining step places greater importance on the data in the neighborhood of each reflectance value, wherein the controller performs the determining step based on linear operators, and wherein the linear operators are represented by C i = Z i ¢ B i b i = w i + C i ¢ Z i T B ¢ i + 1 = B i - C ¢ i T ¢ C i / b i D ¢ i + 1 = D i + S i T ¢ Z i / w i where w ( i ) represents a weighting function that places greater importance on the data in the neighborhood of each actual reflectance value, S i is an i th reference spectrum in the reference database, and Z i is an i th normalized illuminant sensor output in the reference database, the linear operators being recursively computed until i = N , where N is a number of spectral samples in the reference database.

    8.
    发明专利
    未知

    公开(公告)号：DE60042727D1

    公开(公告)日：2009-09-24

    申请号：DE60042727

    申请日：2000-11-21

    Applicant: XEROX CORP

    Inventor： MESTHA LINGAPPA K

    IPC: B41J29/46 ,  G01J3/28 ,  G01J3/02 ,  G01J3/50 ,  G01J3/52 ,  G03G15/00 ,  G03G15/01

    Abstract: A system for automatically re-calibrating a spectrophotometer which is mounted on a color printer for measuring colored test patches printed on test sheets moving thereby, and sequentially illuminated with different color illumination sources. Re-calibration is provided by illuminating, with the same sequenced illumination sources, during a time coinciding with an adjacent gap between the printed sheets, a stationary calibration test patch. This re-calibration timing may be provided by the existing sheets positions tracking control system of the printer.

    9.
    发明专利
    未知

    公开(公告)号：DE69622485D1

    公开(公告)日：2002-08-29

    申请号：DE69622485

    申请日：1996-09-11

    Applicant: XEROX CORP

    Inventor： MESTHA LINGAPPA K

    IPC: G03G15/00 ,  G03G15/04 ,  G03G15/043 ,  G03G15/08 ,  H04N1/407

    Abstract: The method involves storing a reference tone reproduction curve and providing a single test pattern. The print quality is corrected according to the sensed test pattern and reference tone reproduction curve. The test pattern has background, halftone and solid area levels. It is approx. 1 inch square with pixel values varying between 0 and 250 over the length of the test pattern. A single test patch is allocated ramp function with pixel values uniformly varying between 255 to 0. The ramp function pixel values vary along the process direction. They are held to a constant value along the slow scan direction. The pattern looks like a wedge. A tone reproduction curve is extracted by convoluting pixel values of the wedge pattern with a sensor model. The values are plotted with the sensor reading at each sample point in the process direction.

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