A method and apparatus for representing gray scale values in facsimile transmission wherein the gray scale values are produced by a number of dots of equal size per unit area on a recording medium prints the dots in consecutive lines which are displaced by constant distances in order to avoid the generation of dashes running perpendicular to the advancing direction of the printing head. The displacement of the consecutive lines is achieved by the addition of different size constant values to the...

A scanning method for already rastered masters in reproduction technology uses a special diaphragm for avoiding Moire effects in the re-recording.

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...

An apparatus is disclosed for generating a screened reproduction of an image having a scanner and a CPU receiving input density values of an original and coordinate information and storing screening information for providing an operating input to a plotter enabling the plotter to provide a screened image of the original. The CPU is operative to modify at least one of the input density values, the coordinate information and the screening information, thereby to provide an operating input generall...

A plurality of grained screen patterns that are different from each other are previously stored in a grained screen pattern memory. The grained screen patterns are accessed at random in response to an address signal (AGP) generated in a random number generator. An original image data is compared with the random arrangement of the grained screen patterns for each pixel, to produce a halftone dot image. The halftone dot image thus obtained has no periodic distribution of density, such as a moire.

A method and system for reproducing halftone originals utilizing threshold gray level values of the scanned pixels of the halftone original to determine adjacent pairs of pixels bordering the edges of the halftone dots. Edge errors for the adjacent pairs of pixels are determined using the scanned gray level values and a threshold value. A processing window defines sub-arrays of pixels whose thresholded gray level values are processed based on the edge errors. For each sub-array, the edge errors ...

An error diffusion halftoning technique calculates only two error terms with one being divisible by two and the other being divisible by four. This is accomplished through using a modified Floyd and Steinberg type filter preferably having weights of 8-0-4-4 expressed in clockwise sequence from the origin. The direction of scanning is preferably reversed each scan line.

A process eliminates pattern shifting artifacts in a printed image rendered using a hybrid high addressable error diffusion process by perturbing a threshold/image signal value relationship when a multi-level grey level is binarized. The process utilizes a programmable multi-level grey signal modifying circuit for modifying the multi-level grey signal by a predetermined value according to its grey level. The modified multi-level grey signal is binarized to a binary pixel signal according to a re...

A method for operating a circuit arrangement to improve the bounce behavior of an electromagnetically driven engraving system by producing a correction signal from a stored original drive signal and supplying the correction signal to the engraving system chronologically preceding application of the original drive signal.

A process for scanning halftoned images with a sampled or electronic imaging system includes the steps of first optically low-pass filtering the scene, then oversampling the scene at a rate several times that required for display bandwidth, and finally putting the resulting data through an electronic or digital low-pass filter/resampling operation to reduce the system data load. The oversampling advantageously shifts unwanted aliasing between the halftone and sampling frequencies to frequencies ...