Abstract: A method and arrangement for reproducing an original image has a scanner which scans and digitizes the original image into pixels, a controller coupled to the scanner to receive the digitized original image, and a printer coupled to the controller. The controller produces a first signal corresponding to a gray level halftoned representation of the digitized original image, and stabilizes the dots at specified pixels. The printer receives the first signal and reproduces the original image with stable dots at locations corresponding to the specified pixels.

Abstract: A method and apparatus for reproducing an original image, having a scanner which scans and digitizes the original image into pixels, a controller coupled to the scanner to receive the digitized original image, and which produces a first signal corresponding to a gray level halftoned representation of the digitized original image, and a printer coupled to the controller to receive the first signal and which produces a gray level halftoned reproduction of the original image. The controller groups the pixels into cells that each have a determined cell gray level, and controls the formation of dots within the pixels of an individual cell by the printer such that for each increase in cell gray level, a dot at at least one of the pixels in the cell forms to a larger dot-size. Sequential forming of the dots occurs at the pixels in the cell in a pre-defined order such that each dot is formed to a first dot-size less than a maximum dot-size before beginning the formation of a dot at another pixel within the cell.

Abstract: A method and arrangement for reproducing an original image, includes scanning and digitizing an original image into pixels of a digitized image. The pixels of the digitized image are arranged into cells. A gray level halftone printer is then controlled to form dots along lines in accordance with at least a first template corresponding to increasing cell gray levels until a first line structure is stable. The printer is then controlled to form dots along lines in accordance with at least a second template corresponding to further increasing cell gray levels.

Abstract: A method and arrangement for reproducing an original image scans an original image to produce a digitzed image, performs a local structure analysis of the digitized image, and selectively applies a descreening filter to a region of the digitized image based on the results of the local structure analysis to remove a specific frequency of the digitized image caused by halftone screens. The descreening filter bypasses regions of the digitized image such that these bypassed regions remain unfiltered. The filtered regions and the bypassed regions are printed as a single, unified reproduction of the original image. This removes halftone screens from the image while maintaining the contrast of text.

Abstract: A method and arrangement for reproducing an original image, scans and digitizes an original image into pixels of a digitized image. A dot template, a bit-depth, and a dot type structure are selected. A set of gray dot patterns are generated from the dot template, pixel bit-depth and dot type structure that are selected. A 4-quadrant tone reproduction on the set of gray dot patterns is then performed to produce a set of thresholding values at each pixel of the digitized image. A first signal corresponding to a gray level halftoned representation of the digitized image using the thresholding values is then produced. From the first signal, a gray level halftoned reproduction of the original image is printed.

Abstract: A method and arrangement for reproducing an original image scans an original image to digitize the image so as to produce a digitized image signal, and collects statistical information of dot regions from the digitized image signal. For each dot region of the digitized image signal, a dot type is selected to render that dot region in accordance with the statistical information, the dot type being either a mixed dot type or one of a fixed threshold or a partial dot type. A printer is controlled to print the digitized image signal by rendering the dot regions in accordance with the selected dot type for each dot region, so that an original image that may contain different types of image regions is satisfactorily reproduced.

Abstract: A method and apparatus for calibrating a grey level LED printhead or the like to control uniformity of light emissions with a desired criterion such as 2% recording error. A set of possible exposure times is established and from this set a subset of exposure times is assigned to each LED for use in recording the various grey levels. An error is calculated for each LED at each grey level. These errors result from use of available times rather than ideal exposure times. The errors are examined to see if they meet the desired criterion. If the criterion is not met, a new set of possible exposure times is established and the subsequent steps repeated until the criterion is met.

Abstract: An apparatus and method are described for compressing data so that the data scanned in one resolution may be printed or displayed in a second resolution. The apparatus includes a buffer for storing a subset of data representing a matrix of n rows by m columns of data information. The data in the matrix is analyzed and a criterion for selection of a data-stitching locatin is made based upon the arrangement of data in the nxm matrix. The stitching location defines two adjacent rows that are to be stitched. A first shift register is provided for storing an intermediate n x(m-1) matrix of data. The buffer is connected to the first shift register from at least two rows in the buffer other than that of the two rows to be stitched, the shift register and shifting data in said two rows to be stitched by alternately switching between row selections to provide a zig-zag alternating data selection pattern. A second shift register is provided to store an (n-1)x(m-1) matrix of data.

Abstract: Automatic identification of continuous-tone segments of an original document so that such segments can be screened is accomplished by converting the original image into a series of electrical signals characteristic of the optical density gray level of image pixels, calculating the gray level histogram for pixels within defined regions of the original image, and providing signals related to the position of the continuous-tone segment on the basis of the gray level histograms for each region of the original image.

Abstract: A halftone threshold value supermatrix produces different screen frequencies between density steps, but at the same screen angle so as to provide image processing for rendering halftone images with an increased number of gray level steps without changing the apparent screen angle between density steps. A gray level pixel value is compared to a threshold value to make a print or no print decision. The threshold value may come from a j.times.k threshold value supermatrix divided into four equal submatrices of elements such that there is one more ON element in one of the submatrices than in the other three when there are an odd number of ON elements and there are the same number of ON elements in each of the submatrices when there are an even number of ON elements in the supermatrix.