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: 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: 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: An apparatus and method for processing image data operates in a high capacity or a high quality mode. In the former a single bit per pixel is created and processed along one of two identical processing paths. The processing paths involve compression, buffering and expansion for output to a writer interface. The processing path selected for pixels in each image frame is in accordance with the most available buffering memory. In the latter mode two bits per pixel, a more significant bit (MSB) and a less significant bit (LSB) are created and processed simultaneously along the two processing paths. The processing path for each is selected in accordance with the LSB being processed by the processing path with the most available memory. As compression of the LSBs is not as efficient as that of the MSBs, the number of document pages stored in the compression buffers is maximized.

Abstract: An apparatus and method for processing image data operates in a high capacity mode or a high quality mode. In the former a single bit per pixel is created and processed along one of two identical processing paths. The processing paths involve compression, buffering and expansion for output to a writer interface. The processing path selected for pixels in each image frame is in accordance with the most available buffering memory. In the latter mode two bits per pixel, a more significant bit (MSB) and a less significant bit (LSB) are created and processed simultaneously along the two processing paths. The processing path for each is selected in accordance with the LSBs being processed by the processing path with the most available memory. As compression of the LSBs is not as efficient as that of the MSBs, the number of document pages stored in the compression buffers is maximized.

Abstract: A halftoning method for creating a color binary image from a continuous tone color image or computer generated graphics signal is improved by diffusing color vector error and by including the visual color blur functions in the recursive error propagation algorithm so that perceived color vector rather than binary color error is propagated.

Abstract: Thresholding and background referencing apparatus are disclosed for use with apparatus for scanning documents having images with object and background regions. The background referencing apparatus receives, from the scanning apparatus, a video signal representing the document image and generation a signal having a value representative of an estimate of the background density level of the document being scanned. The apparatus produces a difference signal representative of the difference between the estimated background level signal and the received video signal. The estimated background level signal is stored, and updated in response to (1) the difference signal being of a first sign associated with transition from object to background, and (2) only small difference signals of a second sign associated with transition from background to object, whereby large difference signals of the second sign result in substantially no change in the stored estimated background level signal.