Abstract: An image signal processing architecture for image filtering using high and low image resolution scanning arrays to scan a document original. The image pixels produced by the high resolution scanning array are analyzed to determine the presence of high frequency halftone image pixels. Where high frequency halftone image pixels are not found, the image pixels are filtered to enhance the signal content and thereafter thresholded adaptively. Where high frequency halftone image pixels are determined to be present, the pixels produced by the low resolution array are descreened and thereafter rescreened at different screen frequency. A control switch permits the user to process continuous tone images directly. In the principal embodiment, both high and low resolution scanning arrays are disposed on a common substrate to form a unitary structure. In a second embodiment, separate scanning arrays are spaced at preset distances from the object plane to provide the requisite high and low image reading resolutions.

Abstract: An image data handling system to automatically detect and segregate from a stream of image pixels high frequency half-tone image input, continuous tone image input, low frequency half-tone image input, and line image input which may be present in the pixel stream. The image pixels are first autocorrelated in accordance with a predetermined algorithm to detect if high frequency half-tone image data is present. Data of this type found is processed by first descreening and then rescreening at a lower frequency to provide binary level pixels. The pixel stream is analyzed for the presence of continuous tone image data. Where found, such data is processed by a template screening process to provide binary level pixels. Remaining pixels comprising low frequency half-tone and line copy image data are thresholded to provide binary level pixels.

Abstract: Analog image data pixels are sampled and held to produce a box car wave representative of the image data. Wave height differences are bridged by linear interpolation, with frequency enhancement imposed at the bridge junctures. The modified image wave is thresholded and sampled at a multiple of the original frequency to provide an image pixel stream comprised of both original image pixels having one or more interpolated image pixels therebetween.One or more intermediate image lines are interpolated by comparing binary image data, portions of which may be interpolated, on a pixel by pixel or multiple pixel basis one line pair at a time. The pixel comparison produces an address used to identify a specific image pixel pattern from multiple image pixel patterns stored in memory. The image pixel pattern taken from memory is used to form the interpolated intermediate line or lines.

Abstract: A system for compressing or compacting scanned image data is disclosed. The system electronically subdivides the image data pixel pattern into quadrants and predictively encodes pictorial data by predicting, from the established image values of adjoining quadrants, an image value for each quadrant. The predicted image value is then compared with the established image value and the magnitude of the error, if any, determined. The error, if any, is then encoded to provide a relatively highly compressed description of the image suitable for transmittal, storage, and the like.

Abstract: A system for encoding halftone and line copy data having an unknown screen frequency and/or angle is disclosed. The data, in binary pixel form, is inputted to multiple predictors, each adapted to handle different types of imagery. The predictions made are compared with the established values for the pixels predicted and error signals generated. The error signals so produced are compared and the error signal with the least error is chosen for encoding.