Abstract: A method for removing range migration effects that produce doppler smearing in Inverse Synthetic Aperture Radar (ISAR) system (20) image of moving target (50) first generates a synthetic aperture radar image in the zero doppler cells from the target by summing a plurality of ISAR radar data points. Next, the method and system compensate each of the data points by a factor representing the effect of non-zero doppler frequency shift in said data points. Further, the method and system compensate the generated ISAR image for non-zero doppler frequency shift from the target using the compensated data points. This method and system may be used in an ISAR system doppler processor to reduce or eliminate doppler smearing in ISAR images.

Abstract: A method and apparatus relating to image reproduction by displays and printers capable of different dot size or different spot intensity generations. The reproduction is based upon scanned image data including gray scale values individually representing the image intensity at each picture element location (pixel). The display and printing devices generate either different size dots or spots of different intensities at each pixel location. The image processing algorithm assigns to each pixel location an appropriate printing or display dot size (or spot intensity as the case may be) to reproduce an image closely resembling the original. The resulting print dot selection represents both a good approximation of the original gray scale value at that pixel location, and an accurate gray scale reproduction of the image collectively. Additionally, this algorithm is suitable for image reproduction including line copy imagery, halftone and continuous tone pictorials.

Abstract: Print/no-print values are assigned to individual picture elements (pixels) representative of a document to be reproduced or displayed for text, continuous tone, and halftone data. The image data comprises gray scale values individually representative of pixels of a document to be printed or displayed on a bilevel device. The image data is partitioned into data blocks of 2.sup.n .times.2.sup.n matrices of contiguous image data. The average tone density of each data block is determined and a corresponding number specifies how many of the total number of pixels of each data block are to be printed. Each data block is subpartitioned into subblocks comprising contiguous quarters of the block subpartitioned. The pixels to be printed for each subpartitioned block are divided among the subblocks based on the ratio of the average densities of the subblocks to the average density of the subpartitioned block.

Abstract: An ink jet printer for printing a print image on a moving print medium by selectively depositing ink drops at a plurality of print positions arranged in a non-uniform rectangular grid on the medium, such that a plurality of print lines are formed on the medium, includes a print head for generating a plurality of jet drop streams directed at the medium, and arranged in a row which is skewed with respect to the direction of movement of the medium. The drops in each stream are selectively charged and deflected in a direction perpendicular to the row. Each stream services a plurality of print positions and prints a band of print lines. Drops deposited along adjacent print lines by adjacent jets overlap more than drops deposited along adjacent print lines by the same jet.

Abstract: A piezoelectric transducer forms a wall of an ink cavity, which has a linear array of ink jet nozzles communicating therewith. The piezoelectric transducer is preferably an arcuate sector of a cylinder having an angle no greater than 180.degree. with its mean radius, wall thickness, and its arcuate angle selected so that the arcuate sector vibrates only in a selected symmetrical mode at a selected resonant frequency when a voltage is applied at that frequency. The length of the transducer is chosen to be longer than the length of the linear array of nozzles so that the periodic pressure waves produced in the ink cavity by the transducer vibrating at the selected resonant frequency will have substantially the same amplitude at the entrance of each of the nozzles to form droplets of substantially uniform size and at substantially the same break-off point. The applied voltage selected is that which is necessary to produce uniformly satellite free droplets from the array of ink streams.

Abstract: For any selected total number of scanning heads and a required minimum spacing between the scanning heads, the scanning heads are arranged in one or more arrays to read or write substantially parallel lines on a medium or surface at closer distances than the center to center distance of adjacent scanning heads in the indexing direction. The scanning heads in any array do not have to be spaced uniform distances from each other. When the scanning heads are arranged in more than one array, each of the arrays is spaced an arbitrary distance from the adjacent array in the pass direction. To arrange the scanning heads for interlace scanning, they are initially arranged in a single line in the indexing direction with their centers spaced from each other the same distance as the centers of the parallel lines, which are being read or written.