Abstract: A method of printing an image utilizing a printer having print nonuniformities, the method comprising the steps of converting the image into a digital bitmap comprised of an array of pixels wherein each pixel is assigned a digital value representing marking information comprises defining each pixel as either a background pixel, interior pixel, or an edge pixel; and, reassigning the digital value of one or more edge pixels or interior pixels to lower values independently in order to reduce toner consumption. The rendering of the present invention occurs post RIP.

Abstract: A method of rendering the appearance of a printed input digital image comprised of an array of pixels and wherein each pixel is assigned a digital value representing marking information, the method comprising defining each pixel as either a background pixel, interior pixel, or an edge pixel; and, reassigning the digital value of the edge pixels or interior pixels independently of one another. The rendering of the present invention occurs post RIP.

Abstract: A method is described of processing image data of pixels to be rendered. In the method, image data representing a pixel to be rendered is provided. Criteria or tests are established for processing the pixel in accordance with binary error diffusion or multibit error diffusion. In response to examination of the pixel in accordance with the criteria, a decision is made as to whether the pixel is to be rendered in accordance with binary error diffusion or multibit error diffusion. The pixel is then rendered in accordance with the decision.

Abstract: The registration and skew information of a document about to be scanned are detected prior to capturing the entire image of the document. Two sensors, a fixed distance apart, are used to detect the document skew. A third sensor is used to detect the edge position of the document. Paper sensors in the Automatic Document Feeder (ADF) are used to determine the document size. The data from the skew sensors are used to calculate the required skew correction angle and direction by which to rotate the image. The document edge position information together with skew information is used to determine the exact location of a corner of the document. This information is used to correct skewed image in real-time, during scanning the document.

Abstract: Computation of digital gains and offsets used in digital scanners for shading correction (linearity correction) is particularly vulnerable to imperfections in the reference strips, particularly the light reference strip. It is extremely difficult and expensive to create references which are completely free of imperfections or contaminated in some way. This invention eliminates artifacts caused by the presence of small imperfections on the references. It does so by detecting the presence of an artifact and then excluding data contributed by the artifact from the calibration computation process.

Abstract: Computation of digital gains and offsets used in digital scanners for shading correction (linearity correction) is particularly vulnerable to imperfections in the reference strips, particularly the light reference strip. It is extremely difficult and expensive to create references which are completely free of imperfections or contaminated in some way. This invention eliminates artifacts caused by the presence of small imperfections on the references. It does so by detecting the presence of an artifact and then excluding data contributed by the artifact from the calibration computation process.

Abstract: A method is described of processing image data of pixels to be rendered. In the method, image data representing a pixel to be rendered is provided. Criteria or tests are established for processing the pixel in accordance with binary error diffusion or multibit error diffusion. In response to examination of the pixel in accordance with the criteria, a decision is made as to whether the pixel is to be rendered in accordance with binary error diffusion or multibit error diffusion. The pixel is then rendered in accordance with the decision.

Abstract: A block adaptive differential pulse code modulation (DPCM) system includes both a lossless DPCM processor responsive to blocks of pixel values for producing encoder command signals and a lossy DPCM compressor responsive to blocks of pixel values for producing encoder command signals. An encoder receives the encoder command signals from the lossless DPCM processor and lossy DPCM compressor and produces a compressed encoded bit stream. A switch responsive to a compression configuration signal and to the encoder command signals from the lossy compressor selectively passes the encoder command signals from the lossless processor or the lossy compressor to the encoder.

Abstract: A method and apparatus for processing image data of pixels to be rendered for efficient storage in a memory or efficient transmission wherein a grey level value of a rendered pixel is represented by multiple bits including a most significant bit (MSB) and a least significant bit (LSB). The method and apparatus provide for modifying of the density values of successive pixels in accordance with an error diffusion operation. The modified density values are then subject to a thresholding operation wherein the thresholding operation employs position of a pixel to determine the digital value of the LSB of the rendered pixel. There is thereby provided a pattern structure to the LSB data. The rendered pixel values may then be compressed to provide for efficient storage in a memory or for efficient transmission over a communication pathway.

Abstract: Apparatus is disclosed having document recognition capability for determining the size and location of an original document on a scanner platen before the document is scanned for image capture, and which effects both document recognition and image capture within a single scan cycle. A platen is optically scanned in forward and reverse intrack directions, and an electrical information signal characteristic of the optical densities scanned is created. Document recognition is responsive to the electrical information signal produced during the forward direction scan for detecting the boundaries of an original document on the platen. Image capture is responsive to the electrical information signal produced during the reverse direction scan for producing a record of the image on the original document.