Abstract: Methods and apparatus for spectrally-encoding plural source images and for providing the spectrally-encoded plural source images in a composite image, for rendering the composite image in a physical form, or for recovering at least one of the encoded source images from the rendered composite image such that the recovered source image is made distinguishable. Source image confusion in a rendered composite image is controlled by application of a multi-illuminant gray component replacement (GCR) technique to the darkness common to the different colorants under the multiple illuminants.

Abstract: A method of reproducing a document including halftoned regions therein scans the document to generate scanned image data comprising a digitized representation of said document. The scanned image data that corresponds to the halftoned regions is then rendered using a compact rendering process that includes positioning an observation window about a target pixel and a neighboring pixel; selecting a fill-order based upon a result of the analyzing step; and generating a high addressability pixel as a function of the selected fill-order.

Abstract: A compact rendering processor for processing image data including a multi-bit halftone region generates high addressability pixels. The compact rendering processor includes a tagging sub-processor operating on the image data to identify a target pixel and a neighboring pixel to determine a fill-order. The compact rendering processor also includes a rendering sub-processor that converts the target pixel into a high addressability pixel based upon the fill-order. Optionally, a diffusion sub-processor can be included to diffuse an error resulting from the conversion of the target pixel into a high addressability pixel to other pixels within the image data.

Abstract: A method and apparatus for the control of darkness/lightness in a digital image rendered by a printing system. An original image containing antialiased edges is initially thresholded and filtered to determine an edge map. With knowledge of the edge via the edge map, darkness adjustment is applies to the digital image. Gray-edge compaction is applied thereafter to adjust the position of the edge.

Abstract: A method of processing a high addressability binary image comprises converting the high addressability binary image to gray-scale image data; manipulating the gray-scale image data; and rendering the manipulated gray-scale image to a high addressability format using a compact rendering process.

Abstract: A method to compact a diffuse gray edge that is two pixels wide to a state where it is one pixel wide so that it may be well rendered with anti-alias rendering. The method identifies an observation window within continuous tone image data. The method then operates on the pixels within the observation window by: compacting horizontal features within the observation window; compacting vertical features within the observation window; and compacting corner features within the observation window.

Abstract: A method of neutral color detection for use in color copiers and scanners is provided. The method includes reading (10) an input page. The contents of the page are detected (12) and it is determined (14) if the page is neutral in color. If the page is not neutral in color (20), the page is then divided into a number of regions (30). Each region is then detected (40), and a determination (42) is made if individual regions are neutral in color. Next, details located outside regions determined to be neutral in color are detected (70) and it is determined (72) if the details are neutral in color. This multi-resolution technique permits the full page, an individual region, and/or particular details to be processed without the constraints, limitations, and reproduction demands associated with their color counterparts.

Abstract: The present invention is a method and apparatus for the identification and tagging of antialiased pixels within regions of an image. The techniques described improve the recognition of fine gray features and enable the detection of both black and white features on high and low contrast backgrounds. The system relies on the establishment of the sense (positive/negative) of an image by first using a histogramming operation. Once the sense is determined, a plurality of logical channels are used to select a threshold, binarize a region of the image, generate a vector representative of the region, and to process the vector to identify whether an antialiased pixel is present therein. Subsequently, the output of the channels is logically combined to produce an antialias tag.

Abstract: Automatic image enhancement of halftone images is performed by subjecting the halftone image to a low-pass filter so as to smooth out halftone variations between adjacent pixels prior to performing conventional image analysis and image processing.