WO1991006173A1

WO1991006173A1 - Device for making a printing film or colour separation film by means of a drum scanner

Info

Publication number: WO1991006173A1
Application number: PCT/EP1990/000703
Authority: WO
Inventors: Detlev Schmerler
Original assignee: Bbs Ag International
Priority date: 1989-10-23
Filing date: 1990-05-02
Publication date: 1991-05-02
Also published as: DE3935236C1

Abstract

A device for making a printing film or colour separation film comprises a drum scanner (1) for scanning an original (8) to generate digital image information which can be linked to a correcting factor, and a film generation device to produce the printing film and/or colour separation film on the basis of the corrected digital image information. In order to simplify the determination of the correction factor there is a correction factor acquisition device (7) having a colour mixing head (9), a video device (11) and a monitor (12). The correction factors are obtained from the setting of the colour mixing head.

Description

Device for producing a printing film or color separation film by means of a drum scanner

description

The present invention relates to a device for producing a printing film or color separation film according to the preamble of claim 1.

It is generally known to use black-and-white printing or color printing of a drum scanner for the optoelectronic creation of films. A drum scanner is a device which has a drum-shaped holder for a positive or negative original, which is rotatable about its drum axis, wherein during the drum rotation a scanning of the image original is carried out, during which a relative displacement of the scanning device for generating the image signal and the drum in axial direction follows, so that ultimately every pixel of the original is scanned sequentially by rotating the drum and moving it axially. The image signal generated in this way is digitized and broken down by a computer of the drum scanner into individual digitized control signals for the colors yellow, magenta, cyan and black, a printer using these control signals to produce color separation films for the colors yellow, magenta, cyan and a black separation film generated. These films can be used to print the template. Since each original has a certain color cast and its brightness values usually do not correspond to the brightness values of an optimal original, the known drum scanner also has input means for entering color correction values or brightness correction values. These correction values are usually used by the operator in the Ways of estimating after considering the Type of color cast and the strength of the color cast as well as the brightness of the original entered, which, however, only leads to the desired result of the creation of color separation films and black and white separation films with which the brightness and satisfactory prints can be produced with the color values. In order to make it easier to check the effect of the color correction values and brightness correction values set, it is also known in drum scanners according to the prior art to display the result of the drum scanner scanning and color correction or brightness or density correction on a monitor. However, in this case too, checking the correctness of the set color correction values and brightness or density correction values requires a drum scanner scan of the entire original with digitization of the corresponding image signal, which, with a correspondingly high image resolution, results in long processing times before the Monitor image brings with it. In other words, even with a drum scanner provided with a monitor according to the prior art, the effect of a color correction or density correction cannot be detected in real time.

From DE-OS 30 49 349 a system for producing color separation printing plates or printing films is known, in which, in accordance with the known drum scanner system described above, a point-by-point scanning of an original is first carried out, the image signals being digitized again and broken down into color components which can be corrected for their color, the color-corrected image signals of the individual color components being able to be fed to a printer for producing the respective color separation printing plates or color separation printing films. The color-corrected signal can be displayed on an image display. With regard to the type of signal processing and the color correction, this known system corresponds to the drum scanner device described at the beginning. In relation to this prior art, the object of the present invention is to develop a device for producing a printing film or color separation film with a drum scanner in such a way that the determination of a brightness correction value and / or a color correction value for the drum scanner is simplified and made more precise, the time required to determine the relevant correction value is shortened.

This object is achieved by a device for producing a printing film or color separation film according to the preamble of patent claim 1 by the features specified in the characterizing part of patent claim 1.

In contrast to the prior art, the object of the invention is used to determine a correction value by means of an analog, real-time correction value detection device which is essentially formed from a color mixing head, a video device and a monitor. The color mixing head produces a light which can be adjusted in terms of color and brightness for the exposure of the original, which for this purpose is preferably placed on a master stage, the master thus exposed being displayed on a monitor by means of a video device. Every change in the setting of the color mixing head can be detected immediately in real time on the monitor, so that an optimal color mixing head setting for the relevant template can be determined in a simple and time-saving manner. The relevant setting values of the color mixing head can be easily used as color and brightness or density correction values with which the drum scanner works when the same scanner is scanned to produce the printing films or color separation films after the entire system has been calibrated once. However, the brightness and / or color temperature of the light generated by the color mixing head is preferably detected by a sensor, the output signal of which is displayed on a display device, on the basis of the brightness and / or color correction values of the drum scanner can be set. Such manual adjustment is not necessary if the light sensor is connected to the drum scanner via an interface circuit, which derives brightness and / or color correction values for the drum scanner from the brightness and color temperature measured by the light sensor.

For the purposes of the invention, it is not necessary to change the drum scanner in any form, even if it can be connected to the color mixing head via an interface circuit for the purpose of automated input of the correction values.

The color mixing head can be designed both as a subtractive color mixing head and as an additive color mixing head. It can also have an aperture or a density filter.

A preferred embodiment of the device according to the invention for producing a printing film or color separation film is explained in more detail below with reference to the accompanying drawing. It shows:

The only FIG. 1 shows a schematic representation of a preferred embodiment of the device according to the invention for producing a printing film or color separation film.

As shown in the single figure, the device according to the invention for producing a printing film or color separation film comprises a drum scanner 1, which may be of completely conventional design, to which a film production device 2 is connected, for example by a Laser printer can be formed, which in black and white exposes the printing films 2, 3, 4, 5, 6 for the black separation and for the color separations of the colors yellow, magenta and cyan.

Of course, the film forming device 2 needs not be directly connected to the drum scanner 1, but can also be connected to this 1 via a data output device which serves for the data output of control values on any storage medium, in which case the film generating device 2 is connected to a data reading device for the person concerned Data storage medium is connected. Such an arrangement makes a local assignment of the drum scanner 1 to the film generating device 2 superfluous.

The device according to the invention for producing a printing film or color separation film comprises a correction value detection device, which is designated in its entirety by reference numeral 7 and is used to provide a brightness correction value and, in the case of color printing, also color correction values for setting the To generate drum scanner 1 for a specific template 8. The correction value acquisition device includes a color mixing head 9, an original support 10, a video device 11 and a monitor 12 which is connected to the video device 11. The color mixing head 9 is used to generate a light with adjustable brightness and adjustable color temperature, with which the original 8 lying on the original support 10 can be exposed. This template 8 can be a negative as well as a positive. If template 8 is a negative, video device 11 includes a video camera with a color reversal circuit connected downstream. In the case of a positive, the color reversal circuit is unnecessary.

In the preferred embodiment shown, the color correction value detection device includes a light sensor 19, which is arranged between the color mixing head 9 and the original 8 and measures the brightness and color temperature of the light generated by the color mixing head 9. The light sensor 19 displays the brightness and color temperature on a display device 20 to which it is connected. The display device is preferably calibrated or scaled such that the brightness and color temperature are displayed as brightness correction values and color correction values of the drum scanner. On the basis of these display values, the operator can easily set the drum scanner 1.

Likewise, the light sensor 19 can be connected to an interface circuit 17, which in turn is connected on the output side to the drum scanner 1 and is used for the automatic supply of the brightness and color correction values to the drum scanner 1. In this case, in the interface circuit 17 the brightness correction values and color correction values of the drum scanner 1 are assigned to the brightness and color temperature of the light generated by the color mixing head 9 measured by the light sensor 19. These assigned brightness and color correction values are fed to the drum scanner 1.

In the embodiment shown, the color mixing head 9 is a so-called subtractive color mixing head which contains a light source 21 which is followed by an adjustable diaphragm 13 and three color filters for yellow, magenta and cyan 14, 15, 16. Instead of such a subtractive color mixing head, however, an additive color mixing head can also be used, which is formed by three lamps with adjustable brightness, to which fixed color filters are assigned.

The process for producing color separation films using the device according to the invention proceeds as follows:

First, the original 8 is brought onto the original support 10 and the setting of the color mixing head 9 is modified by adjusting the aperture 13 and the color filters 14, 15, 16 until a color-correct and brightness-correct screen image is obtained on the monitor 12. The color temperature of the light generated by the color mixing head 9 in this setting is measured by the light sensor 19, displayed on the display device 20 and / or Interface circuit 17 supplied. If the display device 20 is used, the brightness and color correction values corresponding to the display values are now entered into the drum scanner 1 by hand. In the case of the interface circuit 17, this automatically assigns the brightness and / or color correction values for the drum scanner 1 to the measured values of brightness and color temperature from the light sensor 19. The original 8 is now applied to the drum 18 of the drum scanner 1, the digitized image signal being corrected with the set color correction values and brightness correction values before it is fed to the film producing device 2 in the form of a digital image signal.

In order to match the setting values of the color mixing head 9 to the correction values which have to be supplied to a specific drum scanner 1 in order to achieve an influence on the density or brightness and the color tone of the printing result corresponding to the screen image influence by the color mixing head, a one-off is required initial calibration process. For this purpose, a gray wedge, which is displayed on the monitor 12, is adapted in terms of its density and color temperature to a gray wedge which results as a printed product when the color separation films produced with the device according to the invention are used.

Claims

1. Device for producing a printing film or color separation film

with a drum scanner (1) for scanning a positive or negative original (8) to produce digital image information which can be linked to a brightness correction value and / or a color correction value for generating corrected digital image information, and

with a film generating device (2) for producing the printing film and / or color separation film on the basis of the corrected digital image information,

marked by

a correction value detection device (7) with

- A color mixing head (9) for setting the brightness and / or the color value of the light, with which the template (8) can be exposed to generate a brightness and / or color-correct monitor image, this setting being the brightness and / or color correction ¬ corresponds to correction value,

- A video device (11) for generating a video signal representing the exposed original, and - A monitor (12) for generating the monitor image based on the video signal.

2. Device according to claim 1, characterized in that

that the color mixing head (9) is formed by a subtractive color mixing head which has an adjustable color filter set (14-16) and a light source (21).

3. Device according to claim 1, characterized in that

that the color mixing head is formed by an additive color mixing head which has three lamps which are adjustable in brightness and have assigned fixed color filters.

4. Apparatus according to claim 2 or 3, characterized gekennzeich¬ net,

that the color mixing head (9) has an adjustable diaphragm (13) or an adjustable density filter.

5. Device according to one of claims 1-4, gekennzeich¬ net by

a light sensor (19) arranged between the color mixing head (9) and the template (8) for detecting the brightness and / or color temperature of the light generated by the farm mixing head (9).

6. The device according to claim 5, characterized in that

that the brightness and / or color temperature detected by the light sensor (19) is displayed on a display device (20).

7. The device according to claim 6, characterized in

that the display device (20) generates a display in brightness correction values and / or color correction values of the drum scanner (1).

8. The device according to claim 5, characterized in that

that the light sensor (19) is connected to an interface circuit (17) connected on the output side to the drum scanner (l), which provides the brightness and / or color temperature measured by the light sensor (19) with brightness and / or color correction values for the drum scanner (1) assigns and feeds this.