Abstract: In an input scanning system, as would be present in a digital copier, a “template” of similar visual elements or objects, such as logos and other designs, is detected among a series of scanned images. The common objects form a reference image against which subsequently-recorded input images are compared. If bounding boxes around objects in the input images match those in the reference image, the objects in the bounding boxes are attempted to be matched to those in the reference image. If objects in the input image and reference image match, then the image data from the input image is coded using a pointer to the corresponding object in the reference image.

Abstract: In an image processing system, successive segmentation steps are carried out. In the case of a “hole” in the segmentation result, which is defined as a small area of one type (such as black) within a slightly larger “island” of another type (such as white), a basic segmentation technique may result in an error. The error is avoided by retaining, for each distinct area in the image, a variable indicating whether the area has been “flipped” from one type to another in a previous processing operation.

Abstract: Techniques for black and white pattern rendering that increase processing speed and reduce memory requirements while providing improved pattern selection performance are provided. The hue angle and lightness of a color input are determined. The hue angle is used to index into a lookup table of halftone functions that specify default frequency and spot functions for a hue angle range. For each selected halftone, the determined hue angle is substituted from the hue angle range if the determined hue angle differs from the last determined hue angle range by more than a threshold difference value. The determined lightness is used to determine the halftoning threshold value and rendering then occurs.

Abstract: A method permitting an end user to recalibrate a color reproduction device. The color reproduction device includes a device for converting the native color values of the scanner into a device independent color space, a test target, and the desired values of each patch of the test target. The method includes printing the test target and scanning it with a scanner that forms a part of the color reproduction device. The device compares the desired values with the values obtained from scanning the printed test target to obtain a set of adjustment values to compensate for drift in the output of the color reproduction device. The compensation emphasizes restoration of the overall gray balance of the color reproduction device and can be implemented by modifying the tone reproduction curves or the halftone process used in the color reproduction device.

Abstract: A digital printer outputs a set of test sheets for a calibration operation. Each test sheet bears metadata identifying the test sheet with regard to the calibration operation and the printer which outputted it. The test sheets are fed into a color scanner having a document handler, where downstream software coordinates the scanning operation to yield calibration data for each printer identified on the test sheets. Test sheets from a plurality of printers can be scanned through a document handler, facilitating automatic calibration of a fleet of printers. A network utility can be used to select printers to be calibrated in the fleet of printers.