Linotype-hell Ag

Linotype-hell

Ludo Kerz

A method for generation and storage of digitized threshold density values for use in creating a half-tone image pattern such as in the form of color separations. The threshold density values in a sub-cell of a multiple reference cell (supercell) are stored as storage words in accordance with a spot function. A sorted sequence is determined tailored in accordance with the spot function and threshold density values are allocated to the words in accordance with position of the words in a sorted sequence. Corrections are made to the threshold density values in order to compensate for different numbers of storage words in the subcells.

Method for generating and storing digitalized density threshold values

Method for generating and storing digitized density thresholds for

The object of the invention is a process for generating and storing digitized density thresholds for defining the grid of a half-tone image. The density thresholds of a section of a grid are stored in a data store as stored words depending on a spot function. In the grid section, several spots with a number of stored words form a multiple grid spot and are periodically arranged beside and above one another. A sorted sequence is found for the stored words of the section in accordance with the spot function. Density thresholds are allocated to the stored words depending on the position in the sorted sequence. The actual number of stored words is found individually for each spot in the section. The sorted sequence is generated according to the current spot function. Before position-dependent thresholds are allocated to the stored words, a center of concentration and possibly final point correction is performed for the spot concerned.

The method optimizes frequency-modulated rasters for recording black-and-white or chromatic raster images. An image to be recorded is optoelectronically scanned and is digitally stored in the form of the individual gray scale values that were allocated to the individual pixels. Threshold decisions are implemented using the gray scale values, a decision being made as to whether or not a pixel is set in the rastered recording of the image.

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Saulheim, Germany

Ludo Kerz