Abstract: The present invention implements a CMYK to CMYK pre-transform in front of at least one printer to be clustered where the transform is designed to ensure that the printers addressed through the pre-transform have substantially identical output color for substantially identical input CMYK values. As one form of implementation a method is disclosed to build CMY to CMY 3D-LUTs and 1D-LUT for K using sensors in the field. Making use of a system LUT—CMY to CMY 3D-LUT and a K to K 1D-LUT—improves consistency and provides a coherent control strategy and a means to provide standardized input CMY and K values in a clustered environment so that single or multiple vendor DFEs see substantially identical CMYK values.

Abstract: A method of color management for image marking devices utilizes an automated spot color editor having a control module accessing a graphical user interface. The method includes receiving image data input, in either device-dependent color space or device-independent color space, for a marking job. It is determined whether spot colors are present within the image data input and whether the CMYK values for each of the spot colors present within the image data input are included in the marking device spot color dictionary. Operational parameters for the automated spot color editor are initialized, with operational parameters including the desired performance criteria to be minimized by the automated spot color editor through selection of one or more matrices from a plurality of possible gain matrices to identify new CMYK values. The quality level of the new CMYK values is assessed and new CMYK values are transmitted to image printing device(s).

Abstract: Provided is a method for enabling accurate and consistent imaging of selected colors within a document for various printing device configurations utilizing an automated spot color editor. The method includes determining appropriate target values for a selected color within a print job. The automated spot color editor modifies or adjusts the selected color by selecting a quality level, in the form of a color difference metric, and a maximum number of iterations, which is the maximum number of times the automated spot color editor is operated to calculate a CMYK color formula. Sample patch(es) are printed and analyzed for the selected target value and a CMYK color formula based on the color composition of the sample patch is calculated. The CMYK color formula is inserted into a spot color editing table. Through a graphical user interface, an operator may review the color formula for acceptance.

Abstract: Small, fast, and inexpensive in-line spectrophotometers can produce in-line spectrums of a substrate before or after printing on the substrate. In-line spectrums are generally far less complete than a reference spectrum produced with a large, slow, and expensive reference spectrophotometer. An in-line spectrum can be mapped to a reference spectrum using a variety of known algorithms. However, the mapping is erroneous when the media substrate type changes. Reference transform matrices and in-line transform matrices can correct the erroneous mapping.

Abstract: Tone reproduction curves for calibrating a marking system are obtained using a test pattern with a plurality of patches, preferably a plurality of first test patches extending in a first direction and at least one second test patch extending in a second direction crossing the first direction. Reflectance values are obtained from the first and second test patches. A set of gray balanced tone reproduction curves are obtained based on the reflectance values of the first test patches, and a set of spatial gray balanced tone reproduction curves are obtained based on the reflectance values of the second test patches.

Abstract: Spectrophotometer color measurement with a target illumination system and a reflected illumination sensing system where the target surface is variably spaced from said spectrophotometer. Color correction calibration information corresponding to color measurements for known different spacings of a test target surface from the spectrophotometer are obtained and stored. In use, the spacing of the actual target surface from the spectrophotometer is measured to provide a target spacing information signal. That signal is automatically combined with the stored color correction calibration information for the corresponding distances to provide at least partial correction of color measurement errors of the spectrophotometer for variable spacing of the target surface relative to the spectrophotometer even with low cost fixed focus optics. The spectrophotometer output can be so corrected by changing the target illumination, such as by LED pulse width changes, and/or by corrective adjustment of the measured reflectances.

Abstract: A system and method for printer control and color balance calibration. The system and method address the image quality problems of print engine instability, low quality of color balance and contouring from the calibration. The method includes defining combinations of colorants, such as inks or toners that will be used to print images, defining a desired response for the combinations that are to be used and, in real time, iteratively printing CMY halftone color patches, measuring the printed patches via an in situ sensor and iteratively performing color-balance calibration based on the measurements, accumulating corrections until the measurements are within a predetermined proximity of the desired response. The calibration is performed on the halftones while they are in a high quantization resolution form.

Abstract: Systems and method provide compensation for temperature induced peak wavelength shift of LEDs is color parameter measuring systems that use a model to reconstruct target color parameter values from the reflectance values measured when the target is illuminated by LEDs. Several models may be constructed, with each model being trained at a unique temperature, resulting in a set of models that span the temperature range of interest. In real-time, the LED based color parameter measuring system measures the temperature and interpolates between the models to estimate the appropriate model to use at the temperature of interest. The estimated model is then used to perform the color parameter value estimation.

Abstract: An LED spectrophtometer device for determining an aspect of the color of an object may include: a visible spectrophotometer comprising a plurality of light emitting diodes that emit light in the visible spectrum onto the object; at least one detector for detecting said light after being directed onto the object and for generating an output; and a UV light emitting diode assembly that emits light in the near ultraviolet spectrum and communicates with at least one detector for generating an output. The device may further include a processor that combines the outputs of the at least one detector of the visible spectrophotometer and the at least one detector in communication with the UV light emitting diode assembly.

Abstract: In an image rendering system, a method of compensating for system performance changes related to image attributes includes rendering a diagnostic image, sensing at least one image quality from the diagnostic image, updating an image attribute compensation tone reproduction curve based on the sensed image quality and rendering an image based on the updated image attribute compensation tone reproduction curve. For example, image attributes include print media type and a halftone screen selection. An image processing system operative to perform the method of compensation includes a set of image attribute compensation tone reproduction curves. Each curve of the set is associated with a particular combination of image attributes. For example, each curve is associated with a particular media type/halftone screen combination.

Abstract: A multiple-LED sensor is used to detect area coverage of marked patches on a marking substrate. The same sensor may also be used for color calibration. The marking substrate area coverage sensor obtains reflectance measurements from marked patches of a marking substrate. For example, the marked patches may be patches of a marking substance such as toner, ink or paint, or patches marked by etching or the like. A Neugebauer model may be used to obtain the reflectance measurements. A batch least squares algorithm may be used to estimate the appropriate parameters of the Neugebauer model. For improved accuracy, a recursive least squares algorithm may be used. The recursive least squares algorithm allows the marking substrate area coverage sensor to calibrate itself to changes in the sensing environment.

Abstract: What is disclosed is a method for maintaining consistent color output across printers even when the inline sensors have differences in accuracy due to various technical and environmental factors. A spectrophotometer is used to measure the color quality of printed references. Adjustments are then iteratively made until reference charts of desired color quality are obtained. The printed reference allows one to achieve relatively high system performance by removing sensor inaccuracies. Using the printed reference measured by the inline sensor control systems of each machine are calibrated. At customer sites and at suitable intervals, a reference document can be read using the inline sensor on a reference machine and any differences from expected values can be calibrated out.

Abstract: A full width array spectrophotometer for full width scanning color analysis of color test targets, with one or two substantially linear elongated arrays of closely spaced multiple LED illumination sources of plural different color emissions in a multiply repeated pattern of at least three or four different colors transversely spanning a printer paper path and sequentially illuminated to illuminate a transverse band across a printed sheet moving in the paper path, and a corresponding elongated low cost light imaging bar with a parallel and correspondingly elongated array of multiple closely spaced different color sensitive (three or four rows of color-filtered) photodetectors, which imaging bar is positioned to detect and analyze light reflected from the transverse sequentially illuminated band.

Abstract: A color output device is generally driven by at least three independent control signals for control of its response. A desired response in device independent color space is normally obtained by employing a cascade consisting of a characterization transform and calibration transform. The calibration transform transforms input control variables into output control variables that are directly used to drive the device. Input control variables can be transformed into intermediate control variables, which can be then mapped to output control variables utilizing a two-dimensional transformation. The two-dimensional calibration architecture provides improved control functionality and flexibility.

Abstract: The present invention implements a CMYK to CMYK pre-transform in front of at least one printer to be clustered where the transform is designed to ensure that the printers addressed through the pre-transform have substantially identical output color for substantially identical input CMYK values. As one form of implementation a method is disclosed to build CMY to CMY 3D-LUTs and 1D-LUT for K using sensors in the field. Making use of a system LUT—CMY to CMY 3D-LUT and a K to K 1D-LUT—improves consistency and provides a coherent control strategy and a means to provide standardized input CMY and K values in a clustered environment so that single or multiple vendor DFEs see substantially identical CMYK values.

Abstract: The color management system comprises a state-space based model for a pixel element in a dynamically varying color marking device. A sensor measures the color of the printed output for construction of a selected set of sensitivity functions representative of color output relating to inputs. The gradients of the sensitivity functions are extracted and used to develop the corresponding discrete multivariable state-space model of the pixel element. More particularly, the model is constructed from the Jacobian matrix characterizing a change in measured color output for a change in input color values of the pixel. Extension of modeling methodology for a single pixel is applied to multiple pixel elements.

Abstract: A system and method for printer control and color balance calibration. The system and method address the image quality problems of print engine instability, low quality of color balance and contouring from the calibration. The method includes defining combinations of colorants, such as inks or toners that will be used to print images, defining a desired response for the combinations that are to be used and, in real time, iteratively printing CMY halftone color patches, measuring the printed patches via an in situ sensor and iteratively performing color-balance calibration based on the measurements, accumulating corrections until the measurements are within a predetermined proximity of the desired response. The calibration is performed on the halftones while they are in a high quantization resolution form.

Abstract: Tone reproduction curves for calibrating a marking system are obtained using a test pattern with a plurality of patches, preferably a plurality of first test patches extending in a first direction and at least one second test patch extending in a second direction crossing the first direction. Reflectance values are obtained from the first and second test patches. A set of gray balanced tone reproduction curves are obtained based on the reflectance values of the first test patches, and a set of spatial gray balanced tone reproduction curves are obtained based on the reflectance values of the second test patches.

Abstract: An image transfer apparatus with a scanner and a spectrophotometric sensor interacting logically with the scanner. When the scanner scans a medium containing a color image, the spectrophotometric sensor interacts with the scanner to aid in the automatic selection of a scanner color correction corresponding to the medium being scanned.

Abstract: In an image rendering system, a method of compensating for system performance changes related to image attributes includes rendering a diagnostic image, sensing at least one image quality from the diagnostic image, updating an image attribute compensation tone reproduction curve based on the sensed image quality and rendering an image based on the updated image attribute compensation tone reproduction curve. For example, image attributes include print media type and a halftone screen selection. An image processing system operative to perform the method of compensation includes a set of image attribute compensation tone reproduction curves. Each curve of the set is associated with a particular combination of image attributes. For example, each curve is associated with a particular media type/halftone screen combination.