Method and circuit arrangement for partial correction of the del

Details Method and circuit arrangement for partial correction of the del Method and circuit arrangement for partial correction of the del

1982-05-04

1984-12-04

Masinick, Michael A.

Facsimile and static presentation processing

Static presentation processing

Attribute control

H04N 146

Patent

active

044867727

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The invention relates to electronic reproduction technology, particularly to the production of corrected color separations and relates to a method for the partial correction of the delineation, and also relates to a circuit arrangement for the implementation of the method.


UNDERLYING PRIOR ART

In electronic color reproduction, three primary measured color value signals are gained in a color scanner by means of point-by-point and line-by-line opto-electronic scanning of colored masters and by means of spectral color dissection, said measured color value signals representing the color components red, green and blue of the scanned image points. A color correction computer corrects the measured color value signals according to the regularities of subtractive color mixture and generates the color separation signals which are a measure for the amounts of printing ink required in the later printing.
The color separation signals are deposited in a storage medium as digital color values in order, if need be, to record the color separations at a later point in time or at some other locations or, on the other hand, in order to combine the color values of different individual masters into a data set according to a layout plan, said data set corresponding to an overall page. In order to record the color separations, the color values of the individual masters or of the overall page are read out of the storage medium, are converted back into analog color separation signals and are supplied to write lamps as recording elements whose intensities are modulated by the appertaining color separation signals. The write lamps illuminate a recording medium in the form of films point-by-point and line-by-line, said films, after being developed, representing the desired rastered or unrastered color separations "yellow", "magenta", "cyan" and "black" for producing printing forms.
In the reproduction process, subsequent partial retouches (color value and/or tint value corrections) are frequently necessary, whether it be in order to optimize the correction accomplished in the color correction computer or, on the other hand, in order to take editorial changes and clients' wishes into consideration. Whereas the correction of a color undertaken by means of the color correction computer is effective everywhere where this color occurs in the master or in the image to be reproduced, it is desirable to limit such a retouch to selectable, topically limited image areas. Added thereto is that the correction influence within the image areas to be retouched should also frequently be bleeding, i.e., gradually increasing or decreasing.
A typical retouch job which is carried out in the color separation is the partial improvement of the delineation, i.e., working out finer gradations of the tint value. This retouch job is involved and time-consuming and requires great experience if a bleeding delineation is to be achieved within the image surface to be retouched.
A method is already known from the German No. OS 24 30 762 in which subsequent color corrections can be executed in selected image areas by means of changing the stored image information. Using a coordinate identification device, an operator determines the coordinates of the image points in the picture to be corrected, whereby the address-wise access to the stored image information is created. The operator then inputs the desired correction amounts into a computer over the keys of an operating unit, said computer converting the stored image information into the altered image information by means of evaluation with multiplicative or additive values.
Although color corrections are achieved with the known method by means of inputting individual correction amounts, a method with which a finer gradation of tint value can be executed in order to improve the delineation in an image is not specified.
Moreover, the known method is hardly suited for producing the bleeding retouches with gradually increasing or decreasing influence frequently desired in practice, this being viewed a

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patent: 3972066 (1976-07-01), Seki et al.
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patent: 4236174 (1980-11-01), Gall
patent: 4285009 (1981-08-01), Klopsch
patent: 4307962 (1981-12-01), Jung

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