Abstract: A method for performing visual calibrations on a color printer. For calibrating relative intensities of colors, a predetermined image is printed by an image output apparatus. A user then selects a bias color and an intensity from a reference. The image output apparatus then adjusts its print engine based on the selection. For density calibration an image is printed, preferably once with a light background, and once with a dark background. The user then selects an adjustment after visually comparing the printed image with a reference image and adjusts the printer by noting whether details are missing from the printed image on the light background image or the dark background image.

Abstract: The present invention is directed to a system and method for parameter based visual characteristic control. The system includes input means adapted for receiving image data representative of at least one visual characteristic of an associated image. The system further includes means adapted for storing data representative of a selected polynomial relationship. The system still further includes storage means adapted for storing at least one selected constant value associated with the selected polynomial relationship, which constant values are chosen so as to define at least one curve associated with the selected polynomial relationship. The system also includes calculating means adapted for calculating an output value in accordance with the selected polynomial relationship, stored constant values, and received image data.

Abstract: A color enhancement system with variable color saturation addresses issues of clipping of an output image by analysis and application of color correction to individual pixels. Encoded image data is received, and the elements are converted from a color space representation, such as RGB, into another color space where the individual picture elements are color corrected. The color correction is accomplished by application of a correction matrix. Once correction has been applied, the values are converted back to the original color space representation.

Abstract: A system and method for converting an image to a constrained color palette representation receives a specified color or hue from which an image is to be defined. A conversion is then made from an input color space to a CIELAB representation. Data is converted in CIELAB space, in accordance with a specified hue, to a color space set by the specified color. Once converted, data is converted to a color space corresponding to that of an associated document rendering device.

Abstract: The subject application is directed generally to color conversions and more particularly, to color space conversions for electronic images. The subject application is particularly applicable to conversions made prior to rendering of images by output devices, such as printers, wherein an image encoded in a first multidimensional color space is to be converted to a color space associated with output device prior to rendering.

Abstract: A method and apparatus for enhancing electronic images allows for improved characteristics between light areas and dark areas, and is particularly effective for backlit images. A transition between light and dark image portions is detected. A determination is made from an analysis of spectral distributions as to whether an image portion is backlit. Upon detection, image data is adjusted to lighten or darken image portions to allow for improved image viewing. Use of cumulative probability distribution data associated with an electronic image facilitates isolation of backlit image portions and object image portions.

Abstract: A method and apparatus for enhancing electronic images allows for improved characteristics between light areas and dark areas, and is particularly effective for backlit images. A transition between light and dark image portions is detected. A determination is made from an analysis of spectral distributions as to whether an image portion is backlit. Upon detection, image data is adjusted to lighten or darken image portions to allow for improved image viewing. Use of cumulative probability distribution data associated with an electronic image facilitates isolation of backlit image portions and object image portions.

Abstract: Artifact reduction is achieved by altering the growth of sub-cells for each super-cell in either a pre-determined or random manner. The means of alteration is selected such that the sum of all the groups equals a halftone value. In another embodiment, the random group is selected by using predetermined patterns which are different among sub-cells, such as different means of constructing a dot. Preferably a different pattern is used in adjacent super-cells. In yet another embodiment, the method selects sub-cells patterns that are not aligned on the super-cell boundaries.

Abstract: A method of determining colorant amounts to be laid down in a color printer includes determining an initial set of cyan, magenta and yellow (CMY) values; ordering the initial set of CMY values to determine the largest, middle and smallest values of the three values and generating an ordering vector; selecting a gamut center black generation LUT and two gamut boundary black generation LUTs from a set of black generation LUTs from a selection table; indexing the selected black generation LUTs to determine black values for each black generation LUT as a function of the minimum of the CMY values; interpolating a final output black colorant amount from the black values, and interpolating final output CMY colorant amounts from the initial set of CMY values, the maximum CMY ink limit constraint, and a set of boundary threshold values.

Abstract: A method of transforming scanned RGB values into a colorimetric color space includes identifying multiple input media types to be scanned; assigning a weighting factor to each input media type; dividing input color space into segments; assigning a weighting factor to each input color space segment; applying regression and interpolation techniques to minimize color error; and generating a colorimetric output.

Abstract: A method of determining colorant amounts to be laid down in a color printer includes determining an initial set of cyan, magenta and yellow (CMY) values; ordering the initial set of CMY values to determine the largest, middle and smallest values of the three values and generating an ordering vector; selecting a gamut center black generation LUT and two gamut boundary black generation LUTs from a set of black generation LUTs from a selection table; indexing the selected black generation LUTs to determine black values for each black generation LUT as a function of the minimum of the CMY values; interpolating a final output black colorant amount from the black values, and interpolating final output CMY colorant amounts from the TO initial set of CMY values, the maximum CMY ink limit constraint, and a set of boundary threshold values.

Abstract: A method for improving chromatic text resolution includes transforming a color image signal into chrominance (C1, C2) image signal components and a luminance (L) image signal component. A mask is created for a selected image object from the luminance image signal components. The C1 and C2 image signal components are modified by the mask into new image signal components, C1.sub.NEW, C2.sub.NEW, respectively. The new image signal components are transformed, with L, into a new color image signal that does not have chromatic blur.

Abstract: A method of predictably producing accurate photoprocessing reference image tool photographs to be used for adjusting the parameters of photographic devices, in which a first-generation camera-original image of a scene containing preselected background and subject content is photographed onto a first photographic recording medium. A second first-generation camera-original image of charts containing photoprocessing parameter control information is photographed under the same conditions as the first exposure, onto a second photographic recording medium. The first image is photodigitized into a first digitized image which is stored in a primary digital image data metric in a digital image data base. One or more parameters of the first digitized image are selectively adjusted. Photoprocessing control element(s) (e.g.