Facsimile and static presentation processing – Static presentation processing – Attribute control
Patent
1981-01-08
1983-07-12
Masinick, Michael A.
Facsimile and static presentation processing
Static presentation processing
Attribute control
358 78, H04N 146
Patent
active
043933998
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
TECHNICAL FIELD
The present invention relates to electronic reproduction technology, particularly to a method for partial electronic retouching in color image reproduction in which the color signals generated by means of image-point-wise and trichromatic master scanning are digitized and the digital color values of the individual color components are deposited in a storage medium and in which the stored color values are altered under control; the present invention also relates to a circuit arrangement for implementing the method.
UNDERLYING PRIOR ART
In electronic color reproduction, three primary color measurement signals which represent the color components red, green and blue of the scanned image points are gained in a color scanner by means of point-wise and line-wise opto-electronic scanning of colored masters and by means of spectral color splitting. A color correction computer corrects the color measurement values according to the laws of subtractive color mixing and generates the color separation signals which are a measure for the amounts of printing ink required in the subsequent printing.
The color separation signals are digitized and are deposited as color data in a storage medium in order to record the color separation, if need be, at a later point in time or at some other location or, on the other hand, in order to unite the color data of different individual masters according to a lay-out plan into a data set which corresponds to an overall page.
In order to record the color separation, the color data of the individual masters or of the overall page are read out of the storage medium, are reconverted into analog color separation signals and are supplied to write lamps as recording elements, the light intensities of said lamps being modulated by the appertaining color separation signals. The write lamps expose a recording medium in the form of films point and line wise, said films, after being developed, representing the desired rasterred or unrastered color separations "yellow", "magenta", "Cyan" and "black" for the production of the printing forms.
In the reproduction process, later, partial retouching (corrections of color and/or tint value) are frequently necessary, whether to optimize the correction carried out in the color correction computer or to take, on the other hand, editorial changes and client's wishes into consideration. The retouching, for example, is a matter of incorporating highlights by means of brightening, of working up shadow passages by means of darkening, of improving the drawing by means of brightening and darkening or, simply, of color changes.
Whereas the correction of a color undertaken by the color correction computer takes effect everywhere said color occurs in the master or in the reproduced image, such a retouching is to be limited to selectable, topically limited image areas. Added thereto is the fact that the color influence within the image areas should frequently also be bleeding, i.e., gradually increasing or decreasing, in order, for example, to achieve soft contours or to produce half shadows.
These retouchings are executed in reproduction technology either manually with a retouch pencil in the master itself (master retouching) or, on the other hand, are executed in the individual color separations (separation retouching).
Typical work in master retouching, also called color retouching, are the re-coloring and darkening by means of partial application of glazing or covering retouch inks with the retouch brush, whereby only the color saturation is often to be increased without changing the tint. Likewise, the brightening of image passages by means of bleaching the color layers in the color material with suitable chemicals. It turns out that a re-coloring can only be carried out in such colors as arise by means of subtractive mixing of master colors and retouch colors. Thereby, the selection of the retouch color presumes great experience. Re-coloring in a complementary color is practically impossible. Bleaching can lead
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Gast Uwe
Hennig Eberhard
Preuss Dieter
Taudt Heinz
Wellendorf Klaus
Dr. -Ing. Rudolf Hell GmbH
Masinick Michael A.
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