Dr. Ing. Rudolf Hell Gmbh

Hans Keller

Eggert Jung

Hans-Georg Knop

Heinz Taudt

Rudiger Sommer

Ingo Hoffrichter

Ulrich Sendtko

Klaus Mollgaard

Roman Koll

A method and circuit arrangement for selective correction of hues and colors in the production of color separations for polychromatic mixed printing. A hue signal identifying the hues of the scanned colors as well as a color saturation signal and a luminance signal are derived from the measured color value signals acquired when scanning the original. Hue signals, color saturation signals and luminance signals are limited such that they are respectively not equal to zero only for selectable regions. The region of the hue signal defines a hue to be selectively corrected, and all three regions of the signals define a color to be selectively corrected. At least one of the limited signals is combined with at least one of the unlimited signals to form the selective correction signals which are superimposed on the color signals to be corrected.

Method and circuit arrangement for selective correction of hues and

This invention relates to the production of a printing block or form of the kind in which at least one original is scanned optoelectronically to obtain image signals being mixed to generate a composite signal and is recorded as the printing block or form, one of the image signal which is to be mixed being modulated by a control signal and the other image signal being modulated by the amplitude-inverted control signal and the modulated image signals being summated to obtain said desired composite signal, said control signal determining a mixing range and the mixing characteristic within said mixing range. According to the invention, the said control signal is derived from the color information of a colored control mask by scanning said mask or from the image content of the original.

Production of printing blocks or forms

A process for the identification of a predetermined plurality of colors on the surface of an object which is scanned by electrical-optical means to produce measured signals substantially representing the colors red, green, and blue coordinates, the plurality of colors defining color-regions, and defining color-identification-regions, wherein the boundaries of the identification-regions are simulated electronically through threshold-value circuits for each of the coordinates, the output signals of which are transferred to coincidence circuits, which indicate the presence of one of the plurality of colors when the coordinates of the color signals lie within the color-identification-region.

Apparatus and process for color-identification

A method for the electro-optical reproduction of half-tone pictures in which the picture is subdivided into surface elements having covering spots therein corresponding to a tone value scale, wherein electronic recording data is produced from the surface elements and is stored, wherein by means of electrooptical scanning of a picture signals are obtained and are used to call up the recording data for the reproduction of the picture, the improvement resides in that several raster screens on the picture are formed and the meshes and the angle of rotation of such raster screens are selected in such a manner that an orthogonally oriented parcel screen having a congruent screen structure is obtained, and subdividing the parcels into smaller orthogonally oriented surface elements and obtaining recording data from such surface elements.

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Kiel, Germany

Hans Keller