DE452538C - Process for the production of negatives or positives with the correct color value for the direct copying process onto the machine printing plate using copier machines or pneumatic copying frames by breaking down a colored original into color-filtered negatives produced photographically with a grid - Google Patents

Description

Process for the production of negatives or positives with the correct color value for the direct copying process onto the machine printing plate using Copying machines or pneumatic copying frames by dismantling a colorful template in color-filtered negatives produced photographically with a grid. In the preparation of For mass printing on the offset machine, the copier machine has recently been used. The copying machine allows, for example, on a photosensitive zinc plate a large number of images side by side from a single negative by means of transparency and to produce repeats at high speed and thus surpasses the usual transfer printing iri with regard to the speed, the quality of the execution and the Service life of the printing plates.

If you want to take advantage of the copier machines or the pneumatic copier frame make usable for multi-color printing, there is a difficulty in the Production of the negative to be translucent for the copier. One would to a conventionally produced multicolor print, e.g. B. a four-color print, Sub-panels with the correct color value divided into a cross grid (for example the yellow, red, blue and black) to obtain the negatives for the copier again photograph with cross-raster in the usual way, for example to the To win negatives for yellow, red, blue and black, so would these individual ones Accept negative moiré markings and show loss of tonal values and none of them Way to be more color correct. An impression after copying such negatives the copier would therefore give hues; which are no longer those of the colored ones Conform template.

This drawback is alleviated by the invention described below avoided. The invention consists in that first of all negatives from the colored original for the individual colors, e.g. B. yellow, red, blue, black, can be obtained. Here however, the grid changes from the usual division into a cross grid deviated with the use of round and square panels. Rather, the template will be photographed through slit diaphragms, which with the usual, located in front of the cassette Cross grids work together in such a way that they do not split up on the negative Result in crosses, but divide the image in line grid. The lines run here, for example, from the top right corner of the image to the lower left corner of the same. The slit diaphragms expediently consist of one elongated rectangle with a triangle placed on each of the narrow sides. the The axis of the slit diaphragm is different for the individual color filters. She lies for example, for the yellow pick-up in the vertical, so it is for the red uptake by i5 ° to the left of the vertical and for the blue uptake around Shifted i5 ° to the right of the vertical.

Of the negatives obtained in this way for, for example, yellow, light red, Medium red, dark red, light blue, medium blue, dark blue and deep (black) will be after the usual retouching by hand, a color print is produced in a known manner, which is called Test print is to be approved by the customer and -of which only then the negatives for the copier can be obtained. The test print has the correct color value.

It is now possible to use the colored Test print or from its color part negatives correct color negatives for the copier to be generated by the colored test print preceded by the one described above Slit diaphragms are photographed, but with the diaphragm axis for each color by 30 ° compared to their position when the negatives were taken for the test print is moved. The locking is now linear again, from the upper left corner after the lower right corner of the picture, and splits the negative obtained in this way with the linear grid of the test print to the usual one Cross grid dot formation. The negative is now ready for use in the Copy machine.

The specified method of printing the sample image in linearx Grid and the production of the negatives through a slit diaphragm from this sample image gives the further advantage that while maintaining the correctness of the color values for the negatives for the copier machine partial color images of the individual partial colors of the sample image in a monotone color is merged. can. One has for example in the production of the sample image, the blue is broken down in such a way that one negative for light blue, one negative for medium blue and a negative for dark blue, you can print on top of each other generate a monotone test image of the blue tones by a known method, which for obtaining the blue negative intended for the copier only once needs to be photographed and contains all the color values of blue which the contained three primary blue negatives. It is therefore reduced for use in the copier an original one, resolved in eight colors for the test print Color print on, for example, a four-color print, without any loss of color accuracy to forfeit.

In a corresponding way, positives can also be obtained.

Claims (3)

PATENT CLAIMS: i. Process for the production of negatives with the correct color value or positives for the direct copying process using the machine printing plate of copier machines or pneumatic copier frames by dismantling. a colorful one Original in color-filtered produced photographically with grids and slit diaphragms Negatives, characterized in that they help to obtain a colorful test print the generation of the negatives for the individual color separations usual cross grids are switched, whereupon of the so generated linearly rasterized After known retouching, negatives are colored and with the correct color value in a known manner Test print is made, after its completion of the partial color negatives of the colored :, color-value-correct test print, in turn, negatives are obtained, which can also be made using the slit diaphragms, with the axis the slit diaphragms for each color by 30 ° compared to their position when the picture was taken the negative for the test print, i.e. the first picture, is offset. 2nd embodiment of the method according to claim i, characterized in that the slit diaphragms from consist of elongated rectangles, on the narrow sides of which triangles are placed, and that the axis of the slit diaphragm is different depending on the color to be drawn out Has inclination angle to the vertical. 3. embodiment of the method according to Claims i and 2, characterized in that during the production of the test print Tones of one color (e.g. blue) resolved into partial color images into a monotone color - are printed together, whereupon of this, for example, the three shades of blue containing a sample print containing the three shades of blue, for example Negative for the copier is obtained.