JPH04307534A - Method and apparatus for masking master for reproduction - Google Patents

Abstract

PURPOSE: To duplicate a master capable of producing a copy of an excellent quality, by performing with one of a mask stage for forming the mask or the stage for copying a master to be masked on a photosensitive material to have a low resolution. CONSTITUTION: This device is composed such that the mask matrix 20 is initially transparent when a negative of a film 1 enters into the scanning and printing mechanism, and light from the light source 18 is allowed to pass the matrix 20 and the negative, prior to reaching a rotary reflection body 27. In such a case, the mask formed by the matrix 20 or the image of mask on the negative on a plane of the film 1, or both the mask and the image is severally provided with low resolution, hence being blurred and unclear. Therefore, diffused or unclear intensity distribution is obtained on a photosensitive paper sheet 26. In this way, by making the mask and the image of mask on the plane of the film 1 unclear, the bright/dark gradation on the photosensitive paper sheet 26 generated by the mask corresponding to relative shift or differential expansion between the mask and negative is reduced.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION This invention relates generally to the reproduction of masters.

More particularly, the invention relates to a method and apparatus for masking masters, particularly photographic masters, ready for reproduction.

When a photograph has large brightness variations in individual areas, the bright zones are often overexposed and the dark zones are often underexposed in the reproduction of the photograph. As a result, details and fine structures are reproduced very poorly or not at all in reproductions.

[0004] German Published Publication No. 31 41 263
A method for copying color transparencies onto reversal paper using a mask for contrast reduction is described. The transparency is brought into contact with phototropic glass, and ultraviolet light or the like is irradiated onto the glass through the transparency. A black-and-white mask representing the negative of the transparence is thus produced in phototropic glass. The mask and transparence complex remains in the same position while being illuminated in opposite directions. This results in
Transparencies are reproduced on reversal paper with low contrast.

Because of the abutment between the mask glass and the transparency, a relatively sharp mask is produced in this method and sharply imaged on the reversal sheet. In order to obtain high quality reproductions, it is necessary that the mask and the transparence match virtually 100 percent during exposure. However, this is hampered by the different materials, namely the film material and the glass. During very intense exposure, the material is heated relatively strongly and expands to varying degrees. The reproduction obtained is of low quality and the dark/light tones of the mask, which do not correspond exactly to the dark/light tones of the transparence, are clearly visible.

If the method, as described in the publication, is used in a large laboratory of automatic copiers, it is possible to avoid the rapid impulse transfer that the mask glass and transparency composite undergoes between the individual mechanisms. , additional difficulties arise. The shift occurs again and affects the quality of the copy even more strongly.

[0007]

SUMMARY OF THE INVENTION It is an object of the invention to provide a reproduction method for masters which gives good quality copies.

Another object of the invention is to provide a masking method in which there is only a small relative displacement or differential expansion of the master and mask, which has little effect on copy quality.

Yet another object of the invention is to provide a reproduction device for masters that provides good quality copies.

It is an object of the present invention to provide an apparatus having a mask arrangement with only small relative displacements or differential expansions of master and mask with little or no effect on copy quality.

The above objects, along with other objects that will become apparent as the description progresses, are achieved by the invention.

One aspect of the invention is a method of reproducing masters, particularly photographic masters. The method includes the steps of masking the master and replicating the masked master in a photosensitive material. The masking step involves producing a mask, preferably a black and white mask, representing the negative of the master. At least one of the masking and copying steps includes:
The mask, or the replication of the mask in the master plane, or both the mask and the replication, is at low resolution.
n).

In one embodiment of the method, the mask has low resolution and the copying step includes sharply focusing the mask on the photosensitive material. The resolution of the mask is between 0.1 and 2 line pairs per millimeter, and conveniently 0.7 line pairs per mm.

According to another embodiment of the method, the mask has high resolution, ie, is sharp, and the copying step includes forming a low resolution replica of the mask in the master. This replica of the mask again has a resolution of 0.1 to 2 line pairs per millimeter, and preferably has a resolution of 0.7 line pairs per mm.

According to yet another embodiment of the method, both the mask and the replica in the master have low resolution. Mask and replication are each 0.1-2 per millimeter.
It has a resolution of line pairs, conveniently 0.7 line pairs.

The method further includes scanning the master to generate density values. Masking and/or copying steps are performed using such density values. The result obtained in each of the three embodiments described above is a blurred or diffuse intensity distribution in the photosensitive material or paper. The degree of blur is the sharpness of the master line,
It always appears to be within the blurred image of the corresponding line of the mask. The blurring or diffuseness of the intensity distribution on photosensitive paper depends on the specific magnification. For example, with a conventional small film and an experimental mask resolution of 0.7 line pairs per millimeter, the resolution of the image of the mask in the master plane is is almost at the upper end of the range of
and is approximately at the lower end of the given range for a master with a size of 20 x 25 centimeters.

[0017] Masks are generated in a variety of ways. For example, the mask is produced immaterially and stored in electronic memory in the form of pixels. That is, the act of generating the mask is performed electronically in memory. Exposure of the photosensitive paper is then carried out point by point using a cathode ray tube or laser. It is possible to enter the data in the master into the memory and take such data into account in the data of the mask. In this case, exposure of the photosensitive paper is carried out directly without a master. When the master is transparent, it is possible to expose through the master and further use the data in the mask in calculating the exposure data. The copying step involves transmitting copying light through the master and onto the photosensitive paper. In each of the two procedures, a reduction in contrast is achieved along with an increase in contrast.

[0018] An immaterially generated mask that exists simply as a set of data has the added advantage that the data set can be processed as desired, and the method further comprises processing the mask such that the image is imaged onto photosensitive paper at a reduced scale. For example, the dark areas of the mask are somewhat reduced so that the corresponding light/dark transitions are always within the dark zone of the reproduction and are therefore less noticeable. This further improves copy quality.

[0019] Masks can also be produced materially using phototropic mask elements comprising phototropic glass, phototropic foil or glass with a phototropic coating. When the master is transparent and the operation of creating the mask is performed using a phototropic masking element, the copying step involves transmitting the copying light through the master and the masking element to the photosensitive paper. That is, exposure of the photosensitive paper is performed through a master and a mask.

An intermediate step between a pure non-material mask and a pure material mask is achieved with electronically adjustable mask elements or matrices. Since masks basically exist as data sets, they have the advantage of being changeable. On the other hand, exposure is carried out in the conventional manner used for material masks. Thus, when the master is transparent and the operation of generating the mask is performed using an electronically adjustable mask element or matrix, the copying step
Involves transmitting copying light through the master and onto the photosensitive paper. Point-by-point exposure is not necessary. Depending on the embodiment, a liquid crystal display or an electronically adjustable optical relay arrangement is used as the transparent mask matrix. The mask element or matrix likewise includes a plasma display. Furthermore, reflective electro-optic components whose reflectivity is varied from region to region are commercially available and used to generate masks.

[0021] In order to avoid substantially high illumination intensities and long exposure times with the mask, it is advantageous to design the mask such that the brightest locations produce virtually no darkening effect. The transilluminated mask has maximum transmission at this position. The operation of generating the mask is such that the mask has areas of maximum brightness corresponding to predetermined zones of the photosensitive paper, and the copying step darkens the predetermined zones resulting from the properties of the paper. ie, limiting darkening to the unavoidable bleaching effect caused by the paper.

The method of the invention is advantageously applied in large laboratories with printing or copying machines containing automatic exposure control units and serving to produce paper prints of negative or positive film. The density value (harmonic density) of the masked master must be used for exposure control, and the method further includes the steps of determining a density value for the masked master; and calculating a copying light amount for the copying step using the copying method. The copying step includes automatically controlling the exposure of the photosensitive paper.

In a preferred embodiment of the method, the copy light quantity is obtained purely mathematically. The step of determining a density value for the masked master includes scanning the master or measuring the master using a scanner to obtain a first density value and determining a second density value for the mask from the first density value. and deriving a concentration value. A calculating step is performed using the first and second concentration values. A first density value for the master is stored and a second density value for the mask is obtained from the first density value using a special algorithm. The copying light amount is calculated from two sets of density values: a first density value for the master and a second density value for the mask.

[0024] The copying light amount is calculated in other than purely mathematical ways. To this end, the method again includes the steps of scanning the master to obtain a first density value and deriving a second density value for the mask from the first density value. However, in this case the mask is generated using the second density value, and the density value for the masked master is determined by scanning the master again after the master has been masked with the thus generated mask. It is determined. The density values obtained by measurement of the masked master provide the basis for the calculation of the copying light amount.

The above two procedures for calculating the copying light amount completely automate the copying operation. With the aid of decision logic circuits, e.g. based on the range of contrast,
A determination is made whether a mask has been generated and, if so, how the mask is designed. The method further includes scanning the master to obtain density values and automatically determining the degree of masking using the density values. With such a procedure, high quality copies or prints are produced completely automatically.

In order to make the method of the invention suitable for the highly precise field of professional photography, it is necessary to provide for manual intervention by the operator. This is conveniently accomplished by displaying a first image of the unmasked master and a second image of the masked master. The operator then has the opportunity to evaluate the image and adjust it if necessary. Images may be displayed in color or black and white. A single color or black and white monitor is used to display the image, or alternatively two separate color monitors or two separate black and white monitors are used. An image is created based on the density values obtained by scanning the master.

The operator adjusts the degree of masking, which changes the image from which the master is masked. The effect of the mask level adjustment is immediately evaluated by the operator on a monitor displaying the image of the masked master.

The operator further adjusts the density and color of each image by modifying the image signals, ie, density values for the three primary colors, red, green and blue, generated during scanning of the master. Density values and color modifications are visible in each of the images.

Another aspect of the invention is an apparatus for reproducing masters, particularly photographic masters. The apparatus comprises means for measuring the concentration of the master, means for masking the master, and means for positioning the master at a predetermined location. The mask means includes electrically adjustable mask elements, such as, for example, a mask matrix. The apparatus further comprises means for copying the masked master when the master is in position, and processing means including means for calculating mask densities and controlling the mask elements. The processing means has input means for receiving a concentration signal from the measuring means and output means including at least one output for transmitting a control signal to the mask element.

[0030] The device of the invention is particularly very suitable for carrying out the method according to the invention.

The copying means includes a shutter, while the processing means includes means for determining and controlling the exposure time. The output means of the processing means includes at least one additional output for transmitting a control signal to the shutter.

[0032] The positioning means includes means for transporting the master along a predetermined path including a predetermined location. In one embodiment of the device, the measuring means is arranged at a second position of the path upstream of the predetermined position.

The measuring means includes means for measuring the density of the master in each of the three primary colors, red, green and blue.

[0034] The copying means further comprises an illumination source, and the mask element is disposed between the source and the predetermined position. The copying means also includes means for holding the length of photosensitive material in another position. A second embodiment of the device comprises a directing element between the predetermined position and the other position for directing the radiation onto the measuring means. The directing element is pivotable and includes a beam splitter.

[0035] The calculation means includes a logic circuit.

One embodiment of the apparatus comprises first means for displaying an unmasked master and second means for displaying a masked master. The first and second means each include a color monitor. The measuring means comprises a video camera, preferably a color camera.

The novel features considered characteristic of the invention are pointed out with particularity in the claims. The structure and mode of the improved copying or printing machine as well as the improved copying or printing method are best understood by reading the following detailed description of several specific embodiments when read in conjunction with the accompanying drawings. Probably.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a length or strip of color film 1 is conveyed through a scanning mechanism 2. As shown in FIG. Film 1 is shown in Figure 1.
It is assumed that a series of masters or originals are maintained, which are copied or printed in a copier or printing machine, and that the masters or originals are composed of transparent negatives. The scanning mechanism 2 has a light source 3, a lens 4 and an aperture 5 which serve to scan each negative point by point. The light beam passing through the film 1 is focused by a lens 6 and split by a dichroic beam or beam splitter 7 into the primary colors red, green and blue. The individual color beams impinge on respective rows of measurement cells R, G and B that are sensitive to the corresponding color. Cells R, G and B function to measure the density of the negative in the three primary colors red, green and blue and to generate image signals representing the respective density values. The concentration value is
It is stored in the memory 8 with a resolution of approximately 500-1000 pixels. From the memory 8, the density values for each negative are transferred to a logic circuit 9 which calculates the appropriate mask for each negative.
sent to. This black and white mask represents the corresponding negative in film 1. The mask calculated by the logic circuit 9 is represented by the density signals generated by the logic circuit 9, and the density values corresponding to these density signals are stored in the memory 10. The resulting concentration value is
It is calculated from the mask density value in memory 10 and the negative density value in memory 8. The resulting density values are stored in memory 11. The density of the print or copy made from each negative is calculated in logic circuit 12 using the resulting density values in memory 11. In individual cases, it may be advantageous to additionally use negative density values in memory 8 for this purpose. Calculating print density based on the resulting density values has the advantage that the "density rejection rate" of the printing press is reduced compared to printing without a mask. Logic circuit 12 typically calculates print density based on large area contrast and, as a result,
Errors are easily generated for very high contrast negatives. However, because the large area contrast is actually concentrated by using the resulting density values, the calculated print density best approximates the required copy density.

The calculation unit 13 calculates the exposure time or shutter speed from the print density. The exposure time is stored in the shift register 14 along with the mask density value from the memory 10.
is input.

After passing through the scanning mechanism 2, the film 1 is
It is advanced through a temporary storage zone 15 to a copying or printing mechanism 16. As each negative enters the printing mechanism 16, the corresponding values, ie, the corresponding exposure time and the corresponding mask density value, are recalled from the shift register 14.

The printing mechanism 16 includes a reproduction light source 18 disposed above a condensing unit 17 with a color filter or light mixing arrangement 19, the function and control of which is conventional. Yes, but not listed below. The copying light passes through a collection unit 17 where the color density is collected and impinges on an electrically controlled mask element in the form of an LCD matrix 20 located below the collection unit 17.

The mask density value recalled from the shift register 14 is input to the converter 21 which converts the mask density value into a control signal. These control signals are
It is used to activate the matrix 20 which generates the appropriate mask for each negative in the printing mechanism 16. The exposure time recalled from shift register 14 serves to regulate the length of time that shutter 22 is open during exposure.

The mask is imaged on a dispersion plate 24 via a lens unit or objective lens 23. The mask and negative images in the printing mechanism 16 are transferred to the lens unit 25.
The image is copied on the photosensitive paper 26 registered using .

In FIG. 2, elements having the same function as in FIG. 1 are identified by the same reference numerals.

Referring to FIG. 2, film 1 is transported through a combined scanning and printing mechanism. In this combined scanning and printing mechanism, the light from light source 18 is
The light is transferred to the dispersion plate 24 via the condensing unit 17, the mask matrix 20, and the lens unit 23. film 1
When the negative reaches the combined scanning and printing mechanism, the pivotable reflector 27 is initially pivoted out of the optical path in a manner not shown. Then the negative is the second reflector 2
8 and is imaged indistinctly on the flat black and white CCD 29 of the video camera 30 via suitable optical means. CCD
29 produces an output signal representing a mask for the negative. As mentioned above, the mask is black and white and represents a negative on film 1. The output signal of CCD 29 is converted into a control signal for LCD matrix 20 and stored in memory 31. The control signals are then used to activate matrix 20 and generate a mask for the negative in a combined scan and print mechanism.

Once the mask has been generated and the negative has been masked, the reflector 27 is pivoted into the optical path. The reflector 27 converts the negative masked image into a flat color CCD 3.
2. The CCD 32 generates an output signal representing the resulting density values, ie, density values that take into account both the negative and mask densities in the three primary colors red, green and blue. CCD 32 is coupled to a logic circuit 12 that receives the output signal of CCD 32 and calculates print density from the resulting density values. These values are the color filter or light mixing arrangement 1
Used to control 9.

The reflector arrangements 27, 28 serve as shutters. During exposure, both reflectors 27, 28 are pivoted out of the copying optical path. exposure time, i.e. reflector 27;
The time during which the shutter constituted by 28 is open for exposure is determined by the print density in a conventional manner and need not be detailed. When the shutters 27, 28 are opened, the negative in the combined scanning and printing mechanism is copied onto the photosensitive paper 26, masked through the lens arrangement 25.

In FIG. 3, the mask matrix 20 is shown when the negative of film 1 enters the scanning and printing mechanism.
Initially transparent. Light from light source 18 passes through matrix 20 and the negative before reaching pivotable reflector 27. The reflector 27 directs the light onto a flat color CCD 32, which now forms part of a video camera 33. The negative is thus imaged onto the CCD 32. CCD
32 generates a signal representing a negative color image of the negative, ie a signal representing the density values of the negative in the primary colors red, green and blue. The negative color image is stored in memory 34. From memory 34, the color image is transferred to converter 35, which inverts the image. The resulting positive color image is stored in memory 36 and then displayed on color monitor 37. The negative color image in memory 34 is simultaneously converted into a black and white image in converter 38 and this black and white image is stored in memory 39. memory 39
is connected to a logic circuit 9 which calculates the negative black and white mask. The negative black and white mask derived in the logic circuit 9 is
It is stored in memory 10.

The masked positive color image is stored in the memory 10.
is generated in memory 40 from the mask in and the positive color image in memory 36. This image is displayed on the color monitor 41.

A positive black-and-white mask is generated in converter 42 from the negative black-and-white mask in memory 10. The positive black and white mask from converter 42 is stored in memory 4.
3 is stored. The memory 43 issues signals representing the density values for the stored positive black and white masks, and such signals are converted in the converter 21 into control signals for the mask matrix 20.

The operator directly compares the negative unmasked image shown on monitor 37 with the mechanically masked image shown on monitor 41. Three operating knobs 44 are provided for color correction. The color correction effected by the knob 44 acts directly on the color filter or light mixing arrangement 19 and is thus directly visible on the two monitors 37,41. Another operating knob 45 is provided for mask correction. Correction of the unsharp mask via the operating knob 45 affects the mask gradation in the logic circuit 9 and is therefore directly visible on the monitor 41. monitor 4
An additional operating knob 46 at 1 serves to correct the concentration. The density correction by the operation knob 46 is performed by the shutter 2 through a circuit (not shown) for calculating the printing density.
2 affects the length of time it is open.

When the operator considers the image on monitor 41 to be optimal, the exposure procedure begins. For this purpose, a mask matrix 20 is first activated and
The reflector 27 is pivoted out of the optical path, and the shutter 22
will be released. The negative in the scanning and printing mechanism is printed on a photosensitive paper 26 through a lens arrangement 25 with a mask.

Of course, it is possible to eliminate the need for the monitor 37 and display only the masked positive image on the monitor 41. However, in order to optimize the operator's judgment, it has been found advantageous to compare the masked image with the unmasked image.

The mask formed in the matrix 20, or the image of the mask on the negative in the plane of the film 1, or both the mask and the image, has a low resolution, ie is blurred or indistinct. As a result, a diffuse or blurred intensity distribution is obtained on the photosensitive paper 26. By blurring the mask and/or the image of the mask in the plane of the film 1, the light/dark tones in the photosensitive paper 26 produced by the mask in response to the relative shift or differential expansion of the mask and negative are greatly reduced. be done. Print quality is thus improved.

[0055] For example, the negative is 10
It has line pair resolution. In contrast, the resolution of the image of the mask in the plane of the mask and/or film 11 is
0.1 to 2 line pairs per mm, and preferably 0.7 line pairs per mm. A low resolution mask is obtained by selecting a mask matrix 20 of appropriate roughness. The image of the mask in the plane of the film 1 is made to have a low resolution by appropriate adjustment of the lens unit or objective, for example by defocusing.

According to one embodiment of the invention, the mask has a low resolution and the copying mechanism is operated such that a sharp image of the mask is formed on the photosensitive paper 26. According to another embodiment of the invention, the mask is sharp, ie has a high resolution, and the copying mechanism is implemented such that the image of the mask in the plane of the film 1 has a low resolution.

In an additional embodiment of the invention, the mask has a low resolution and the copying mechanism is implemented in such a way that the image of the mask in the plane of the film 1 likewise has a low resolution.

Although the invention has been described with reference to the reproduction of photographic negatives, it applies equally to the reproduction of photographic positives.

Without further analysis, the foregoing is clear from the perspective of the prior art, without omitting features that fairly constitute essential characteristics of the general and particular aspects contributing to the art, and which others may use in the present state of knowledge. The subject matter of the invention is sufficiently clear that it can be easily adapted to a variety of applications by applying the following: intended to be included.

The main features and aspects of the present invention are as follows.

1. A method of replicating a master, comprising the steps of masking the master, the masking step comprising creating a mask representing a negative of the master, and the step of copying the masked master onto a photosensitive material, the mask and A method of replicating a master, wherein at least one of the copying steps is performed such that the mask or the reproduction of the mask in the master, or both the mask and the reproduction, have a low resolution.

2. 2. The method of claim 1, wherein the mask has low resolution and the copying step includes sharply focusing the mask on the material.

3. The mask has approximately 0 per millimeter
．． 3. The method of claim 2, having a resolution of 1 to about 2 line pairs.

4. 3. The method according to 3 above, wherein the mask is black and white.

5. 2. The method of claim 1, wherein the mask has high resolution and the copying step includes forming a low resolution reproduction of the mask in the master.

6. The reproduction is approximately 0.0 mm per millimeter.
6. The method of claim 5, having a resolution of 1 to about 2 line pairs.

7. 7. The method according to 6 above, wherein the mask is black and white.

8. 2. The method of claim 1, wherein the mask and the reproduction have low resolution.

9. 9. The method of claim 8, wherein the mask and the reproduction each have a resolution of about 0.1 to about 2 line pairs per millimeter.

10. 10. The method according to 9 above, wherein the mask is black and white.

11. 2. The method of claim 1, further comprising scanning the master to generate density values, and wherein at least one of the masking and copying steps is performed using the density values.

12. 2. The method according to claim 1, wherein said generation is performed electronically.

13. 13. The method of claim 12, wherein the copying step includes exposing the material point by point.

14. 14. The method according to 13 above, wherein the exposure is performed using a cathode ray tube or a laser.

15. 13. The method of claim 12, further comprising processing the mask such that regions of the mask having a predetermined intensity are imaged onto the material at a reduced scale.

16. 13. The method of claim 12, wherein the master is transparent and the copying step includes transmitting copying light through the master and into the material.

17. 2. The method of claim 1, wherein the master is transparent and the generation is performed using a phototropic masking element, and the copying step includes transmitting copying light through the master and the element to the material. Method.

18. 18. The method of claim 17, wherein the element comprises glass or foil.

19. 2. The method of claim 1, wherein the master is transparent and the generation is performed using an electronically adjustable mask element, and the copying step comprises transmitting copying light through the master and into the material. Method.

20. 20. The method of claim 19, wherein the element comprises an electro-optic component.

21. 1 above, wherein the element comprises an optical relay;
9.

22. 20. The method of claim 19, wherein the element comprises a liquid crystal display or a plasma display.

23. 2. The method according to claim 1, wherein said generation is performed using a reflector.

24. the generation is performed such that the mask has areas of maximum brightness corresponding to predetermined zones of the material;
2. The method of claim 1, wherein the step of copying comprises limiting the darkening of the zone to that resulting from the properties of the material.

25. 2. The method of claim 1, further comprising the steps of determining a density value for the masked master and using the density value to calculate a copying light amount for the copying step.

26. 27. The method of claim 26, wherein the copying step includes automatically controlling exposure of the material.

27. The determining step includes scanning the master to obtain a first density value and deriving a second density value for the mask from the first density value, and the calculating step includes scanning the master to obtain a first density value and deriving a second density value for the mask from the first density value. The above 2 is done using the second concentration value.
The method described in 5.

28. further comprising the steps of: scanning the master to obtain a first density value; and deriving a second density value for the mask from the first density value, where the masking step includes the steps of scanning the master to obtain a first density value; 26. The method of claim 25, comprising generating the mask using a mask, and the determining step comprising scanning the master if masked with the thus generated mask.

29. 2. The method of claim 1, further comprising scanning the master to obtain density values and using the density values to automatically determine the degree of masking. 30. 2. The method of claim 1, further comprising displaying a first image of the master without a mask, displaying a second image of the master while masked, and evaluating the images.

31. 31. The method according to item 30, wherein at least one of the images is in color.

32. 31. The method according to item 30, wherein at least one of the images is black and white.

33. 31. The method of claim 30, further comprising adjusting the second image by changing the degree of masking.

34. 31. The method of claim 30, further comprising adjusting the density and color of each of the images.

35. The method according to 1 above, wherein the master is a photographic master.

36. An apparatus for replicating a master, comprising: means for measuring the concentration of the master; means for masking the master, the masking means comprising an electrically adjustable mask element; and means for positioning the master in a predetermined position. means for copying a masked master when the master is in the predetermined position; and means for calculating a mask density and controlling the mask elements; Apparatus comprising processing means having input means for receiving a concentration signal from the measuring means and output means including at least one output for transmitting a control signal to the mask element.

37. The copying means comprises a shutter, the processing means includes means for determining and controlling exposure time, and the output means includes at least one additional output for conveying a control signal to the shutter. 37. The device according to 36 above.

38. 38. The apparatus of claim 37, wherein the mask element comprises a matrix.

39. 39. The apparatus according to claim 38, wherein the measuring means comprises means for measuring the density of the master in each of the three primary colors red, green and blue.

40. The positioning means comprises means for transporting the master along a predetermined path including the predetermined location, and the measuring means is disposed at a second location of the path upstream of the predetermined location. 39. The device according to 39.

41. 37. The apparatus of claim 36, wherein said copying means comprises an illumination source and said mask element is disposed between said source and said predetermined location.

0101 42. 42, wherein said copying means comprises means for holding a length of photosensitive material in another position and a directing element between said predetermined position and another position for directing radiation to said measuring means. equipment.

43. 4 above, wherein the pointing element is pivotable;
2. The device according to 2.

44. 43. The device of claim 42, wherein the directing element is a beam splitter.

45. 43. The device according to 42 above, wherein the calculation means comprises a logic circuit.

46. 37. The apparatus of claim 36, further comprising first means for displaying the master while unmasked and second means for displaying the master while masked. 47. 47. The apparatus of claim 46, wherein each of the first and second means comprises a color monitor.

48. 47. The apparatus according to 46 above, wherein the measuring means comprises a video camera.

49. 49. The device according to 48 above, wherein the camera is a color camera.

[Brief explanation of drawings]

1 schematically shows a printing press according to the invention operating with purely mathematical exposure control; FIG.

FIG. 2 schematically shows a printing press in which the exposure is controlled by measurement;

FIG. 3 schematically shows a printing press particularly suitable for professional photography.

[Explanation of symbols]

1 Color film 2 Scanning mechanism 3. Light source 4 Lens 5 Aperture 6 Lens 7 Beam splitter 8 Memory 9 Logic circuit 10 Memory 11 Memory 12 Logic circuit 13 Calculation unit 14 Shift register 16 Printing mechanism 17. Condensing unit 27 Reflector 28 Reflector 29 CCD 32 CCD 33 Video camera 34 Memory

Claims (2)

[Claims] 1. A method of copying a master, comprising the steps of: masking the master, the masking step comprising generating a mask representing a negative of the master; and copying the masked master onto a photosensitive material. A method of replicating a master, wherein at least one of the masking and copying steps is performed such that the mask or the reproduction of the mask in the master, or both the mask and the reproduction, have a low resolution. 2. An apparatus for replicating a master, comprising: means for measuring the concentration of the master; means for masking the master, the masking means comprising an electrically adjustable mask element; processing means including means for positioning a master in the predetermined position; means for copying a masked master when the master is in the predetermined position; and means for calculating a mask density and controlling the mask elements. and the processing means has input means for receiving a concentration signal from the measuring means and output means including at least one output for transmitting a control signal to the mask element. Equipment to be equipped.