Eastman-kodak Company

Kodak Alaris Inc.

Kevin C Scott

Kevin Edward Spaulding

Stuart Gerard Evans

Steven R Schmidt

Roger A Morton

Mark R Knudson

Gregory J Wolfe

A method of calibrating a printer using a reflective scanner is disclosed. Because the reflective scanner used for calibration may only be able to accurately measure a limited density range that is less than the full density range of the printer, some information from the reflective scanner is disregarded or deemphasized during the calibration process. A calibration page is printed and scanned. Lookup tables (LUTs) that comprise the printer calibration values are updated based on adjustments calculated from the scanner for density regions where the scanner produces relatively accurate measurements, but updated based on the preexisting settings for density regions where the scanner produces relatively inaccurate measurements. In transitions regions between accurate and inaccurate regions, the LUTs are adjusted based on a combination of measurements from the scanner and the preexisting settings.

Printer calibration using limited range reflection scanners as input sources

A method and apparatus for adjusting a color in an image to a desired color value is described, wherein the method includes identifying at least a first portion of the image including the color to be adjusted; analyzing the first portion to determine a representative color value; determining a color adjustment parameter to adjust the representative color value to the desired color value; and applying the color adjustment parameter to at least the first portion of the image. The method can further include performing a desaturation of the first portion of the image before analyzing to determine a color value, and resaturating the color value; identifying at least a second portion of the image having a color value extreme to determine a color value representative of the color value extreme, and using the second portion color value in determining the color adjustment parameter; or a combination thereof.

Color correction method

A method for transforming input color values to device control signals for a color printing device having an output response that is approximately invariant for ranges of the device control signals near the maximum or minimum allowable device control signals, wherein the input color values are transformed into the device control signals that are to be used to reproduce the input color values is disclosed. The method includes determining color reproduction characteristics for the color printing device over an allowable range of input signal values; determining a full color gamut for the color printing device describing a full range of color values that can be produced by the color printing device; creating a reduced color gamut by shrinking the full color gamut; and transforming the input color values to the device control signals using the determined color reproduction characteristics of the color printing device, wherein the input color values that are outside the reduced color gamut are mapped to color values that are on or within the reduced color gamut.

Transforming input color values to device control signals

A technique, applicable for use in implementing a print preview function in a color electronic imaging system, that, under a variety of different ambient lighting conditions, will yield a highly acceptable color match between a color image appearing on a CRT monitor and that which will be produced by the system as a printed version of the same image. Specifically, a computer system (120) is employed to scan an image and, through an ambient illumination sensor (27), senses the spectral content of the ambient illumination. The computer displays the scanned image along with various non-image information which can be used to adjust the color of the image. The computer transforms the color of the scanned image and the non-image information such that a resultant display of the image and the non-image information on a color monitor (24) will show the appearance of a print when the print is viewed under the ambient illumination. The transformation of the non-image information includes transforming non-image monitor control signals into a first set of tristimulus values which are, in turn, transformed into printer control signals for an imaginary printer. These printer control signals are then transformed into tristimulus values using the sensed spectral content of the illuminant. This latter set of values are used to produce monitor control signals that are applied to the monitor.

Technique particularly suited for use in a print preview function for

This invention minimizes the visibility of quantization artifacts associated with multi-dimensional color-calibration look-up tables of a limited size. Such artifacts occur when it is not practical to use interpolation methods to approximate color values which are intermediate to the color values stored in the look-up table. In such cases the input color signals are simply quantized for the purpose of addressing the look-up table. This invention works by applying local mean preserving spatial modulation to the input color image values prior to the quantization step. As with multi-level halftoning techniques, the result is that the appearance of intermediate color values is created because the observer will spatially average the output color values.

Method and apparatus employing mean preserving spatial modulation for

Image processing systems and methods for retrieving digital data stored in a plurality of contiguous data cells on photographic film. An image sensor samples the image data at a plurality of pixel positions in each of the data cells and generates grayscale image data that is processed into a one-dimensional stream of binary pixels. A data sampling system processes the binary pixels by first selecting those binary pixels that correspond to the data cell centers. Then, a digital output signal is constructed from the selected pixels to represent the original data stored on the film. The stream of binary pixels are read in series. In particular, transitions, detected in the stream of binary pixels, are used to periodically estimate the data cell pitch and the transition phase. A plurality of, e.g. N, suggested distances from the current pixel to the next sampling point are located using the transition phases of the most recent N transitions. A preferred sampling phase is determined through a histogram to find a consensus among the N suggested distances. The digital output signal is constructed from those pixels that occur at the preferred sampling phase.

'Consensus sync' data-sampling systems and methods

A bidirectional adaptive thresholding technique for use in an image processing system. An array of pixel sensors scans a grayscale image and generates a set of grayscale image data. A buffer storage connected to the sensors stores the grayscale image data. A forward tracker reads the image data from the buffer storage in a forward direction and provides background and peak forward tracked values. A reverse tracker reads the image data in a reverse direction and provides background and peak reverse tracked values. A threshold level generating circuit generates a threshold level that is a proportional function of either the forward or reverse tracked values based on validity criteria. Thereafter, a thresholding circuit thresholds the grayscale image data using the threshold level to provide binary image data.

System and method for bidirectional adaptive thresholding

In a non-impact printer apparatus, such as an LED printer, multiple bits of image data determining the on-time of each LED for generating a grey level pixel are latched into an appropriate data register from a data bus in accordance with a token bit that is passed along a shift register. The data register for each LED comprises a series of cascaded registers coupled as a ripple counter. Each of these registers stores a respective binary weighted data bit. In response to a clock signal at one of the clock inputs of one register the counter effectively counts down to a zero output condition and thereby directly controls LED enablement time.

Non-impact printer apparatus for grey level printing

Apparatus and accompanying method(s) digitally scaling, particularly reducing, an original image to yield a scaled image particularly suited for display by a document workstation in an image management system as one image in a composite multi-image display. Reduction scaling is achieved by mapping source pixels into destination pixels. Specifically, a reduced image is produced by moving through a source image by increments of a single full pixel with corresponding movement through a destination image in fractional movements in order to define corresponding pairs of pixel coordinate addresses in both images, i.e. one pixel coordinate address in the original image and a corresponding pixel coordinate address in the enlarged image. Once a pair of these addresses is defined, a current pixel in the enlarged image is set to the value of its corresponding pixel in the source image, with both of these pixels being defined by the integer values of their associated coordinate addresses. To digitally enlarge (magnify) the source image, incremental movement occurs on a pixel-by-pixel basis, both horizontally and vertically, in an enlarged image with fractional movement, in either both directions depending upon the desired scale factors, occurring in the source image. Given these incremental movements, the pixel values that occur at successive integer pixel coordinate addresses in the source image are merely copied, i.e. replicated, rather than mapped into corresponding integer pixel coordinate locations in the enlarged image.

Digital image scaling by stepwise pixel movement

Apparatus and accompanying method(s) for digitally scaling, particularly reducing, an original image to yield a scaled image particularly suited for display by a document workstation in an image management system as one image in a composite multi-image display. Reduction scaling is achieved by logically combining pixels values in each block of pixels in an original bi-tonal image, preferably through an 'OR' operation, in order to generate a corresponding single pixel value in a scaled bi-tonal image. To reduce the original image by a non-integer scale factor, the pixel blocks that form the original image are assigned differing groupsizes that periodically vary on a two-dimensional pattern from block to block throughout the original image. The average value of the periodic variation occurring in each direction throughout a sufficiently large two-dimensional area in the original image substantially equals the fractional portion of the non-integer scale factor. If integer scaling is desired in either the horizontal or vertical direction, then the groupsize remains the same along that direction from block to block throughout the original image. Alternatively, to digitally enlarge (magnify) an original bi-tonal image, each pixel in the original image is replicated to form a corresponding block of pixels in a destination (enlarged) image. In order to two-dimensionally magnify the source image by non-integer scale factors in both the horizontal and vertical directions, the groupsize of successive pixel blocks in the destination image is appropriately varied, also through a corresponding two-dimensional pattern. The groupsize remains fixed along either direction if the original image is to be magnified along that direction by an integer scale factor.

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Rochester, NY, United States of America

Kevin C Scott