Abstract: An apparatus and method for providing bit-rate reduction and reconstruction of image data. Bit-rate reduction of 32-bit CMYK combinations into 16-bit code words is performed on a pixel by pixel basis by stepwise calculations or by using LUTs. Bit-rate reduction takes place during PostScript.RTM. interpretation where the output image pixels are generated in a possibly arbitrary order. Bit expansion from 16-bit code words to 32-bit data for 8 bits per component of the CMYK image values is performed while real time printing, preferably by direct table look up. During bit-rate reduction, the image data may be non-linearly corrected to compensate for perceptual non-uniformities and for non-linearities in the input/output relationship of the reproduction device. Quantization and coding may be accomplished by thresholding the non-linearly corrected image data by values from a dither array.

Abstract: The present invention is a method for calibrating color reproduction devices such as printers and for stabilizing the print colors generated by a computer controlled color reproduction device. Further, the present invention acts to standardize the print colors produced across a family or series of color reproduction devices. It may be incorporated into a color management system used to produce consistent colors across a variety of reproduction devices. In the first embodiment of the present invention, an object scanning device and an object color reproduction device are used. In the second embodiment, an object densitometer is used as the measuring device to measure densities. In yet another embodiment, an object colorimeter is used as the measuring device to measure CIE values. The present invention enables generation of a set of calibration curves for correcting the color output of the color reproduction device.

Abstract: A method and apparatus for efficiently handling, modifying, transmitting, re-displaying and storing color images is described. An image is provided which has a plurality of pixels each having color parameters (information) in the form of color coordinates which can be considered a color point in a color space. The invention provides a plurality of color volume elements which together contain at least a portion of the color space and which in effect quantize the color space. Each color volume element has a representative color value (point) so that a first plurality of representative color values (points) are provided by the plurality of volume elements. A representative color value is determined for each pixel in the image such that, with a typical image, a subset of the first plurality of representative color values are determined. In other words, the image will not use all the values in the first plurality of representative color values.

Abstract: A method and apparatus for modifying colors in an image displayed on a display device by a computer controlled display system. The method includes selecting at least one color being representative of at least one pixel of the image, where the image includes a plurality of pixels on the display device; determining the colorimetric values for the at least one color; selecting a second color and determining the colorimetric values for the second color; and modifying the colorimetric values of a plurality of pixels in said image such that for any given pixel of the plurality of pixels having colorimetric values being matched to the colorimetric values of the at least one color, then the colorimetric values of the given pixel are modified to match the colorimetric values of the second color.

Abstract: A method and apparatus for color processing of an image displayed on a display device of a computer controlled display system. The method comprises storing the first image and a second image in a first memory; displaying the first image on the display device; displaying the second image on the display device; storing a first color information for the first image in a second memory; storing a second color information for the second image in a third memory; modifying the display of the first image by storing a third color information into the second memory. An example of an apparatus for performing this method includes a frame buffer for storing the first and second image in a computer controlled display device with a processor for controlling the display device. The apparatus further includes a memory for storing the color information, such as a video look-up table.

Abstract: A method and apparatus for efficiently handling, modifying, transmitting, re-displaying and storing color images. An image is provided which has a plurality of pixels each having color parameters (information) in the form of color coordinates which can be considered a color point in a color space. The invention provides a plurality of color volume elements which together contain at least a portion of the color space and which in effect quantize the color space. Each color volume element has a representative color value (point) so that a first plurality of representative color values (points) are provided by the plurality of volume elements. A representative color value is determined for each pixel in the image such that, with a typical image, a subset of the first plurality of representative color values are determined. In other words, the image will not use all the values in the first plurality of representative color values.

Abstract: The color correction system will enhance an operator's ability to edit and correct the appearance of a color image. This system is particularly useful in desk-top publishing applications. A reference image with an overall desired visual impression is displayed on a screen. This reference image is known to print in an acceptable fashion and give a desired visual impression. When the image to be corrected is modified in order to approximate the visual impression of a reference picture, then the picture to be corrected should print acceptably.