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:
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:
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 LUTnullCMY to CMY 3D-LUT and a K to K 1D-LUTnullimproves 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 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:
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:
In a color analysis system in which sheets with multiple different color printed test patches are moved relative to a color analyzing spectrophotometer, and in which fiducial marks are printed adjacent to respective test patches and optically detected by a fiducial mark detector to provide a triggering system for the respective test patch analysis, there is provided automatic diagnostic testing of the spectrophotometer and the fiducial mark triggering system, including automatically generating special test sheets, some of which may include test areas of varying density black.
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 method is provided for measuring the color of irregular surface materials, including textiles which may provide dissimilar color measurements from different viewing angles, by illuminating a sampling area of the irregular surface material approximately perpendicularly thereto and measuring the color reflected from that area at a substantial angle, preferably about 45 degrees, with a plurality of separate photodetectors arrayed circularly around the illuminated sampling area of irregular surface material to receive the reflected illumination from substantially opposing directions and at a substantial angle to the illuminated area, for providing a more accurate yet lower cost color measurement system for textiles that can be used easily, quickly, and uncritically in terms of the handling, positioning and orientation of the textile material being tested.
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 color sensor monitors the output of a color producing process and produces a signal representative of a color produced by the color producing process. The signal can be used as feedback signal to control the process. Occasionally, the color sensor signal includes a component representing a transient error. A system model of the color producing process is used to predict reasonable sensor signals. A comparison of the sensor signal with the predicted sensor signals is used to determine if the sensor signal is reasonable. If the sensor signal is unreasonable, a substitute signal is used as the feedback signal to the control process. The substitute signal can be a predicted sensor signal or a signal based on historical system performance data.