CA1147188A - Pre-press color proofing by light exposure to photographic media - Google Patents
Pre-press color proofing by light exposure to photographic mediaInfo
- Publication number
- CA1147188A CA1147188A CA000344241A CA344241A CA1147188A CA 1147188 A CA1147188 A CA 1147188A CA 000344241 A CA000344241 A CA 000344241A CA 344241 A CA344241 A CA 344241A CA 1147188 A CA1147188 A CA 1147188A
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- CA
- Canada
- Prior art keywords
- color
- target
- given
- filters
- photographic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
- B41C1/00—Forme preparation
- B41C1/12—Multicolour formes
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
- B41M1/00—Inking and printing with a printer's forme
- B41M1/14—Multicolour printing
- B41M1/18—Printing one ink over another
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F3/00—Colour separation; Correction of tonal value
- G03F3/04—Colour separation; Correction of tonal value by photographic means
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F3/00—Colour separation; Correction of tonal value
- G03F3/10—Checking the colour or tonal value of separation negatives or positives
- G03F3/101—Colour or tonal value checking by non-photographic means or by means other than using non-impact printing methods or duplicating or marking methods covered by B41M5/00
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Spectrometry And Color Measurement (AREA)
- Silver Salt Photography Or Processing Solution Therefor (AREA)
Abstract
PRE-PRESS COLOR PROOFING BY LIGHT
EXPOSURE TO PHOTOGRAPHIC MEDIA
Abstract of the Disclosure Pre-Press color proofing of a set of color separation films from which printing plates are to be made for color printing of a multi-color image on a paper or like printing base with a given set of printer's inks or the like, by:
(a) preparing samples of the given inks or the like on the printing base or equivalent thereof;
(b) determining the primary color component makeup of each sample in relation to a given illuminant source and from a color reference data base based on such illuminant source, determining a group of color filters and associated color filter exposure times appropriate to substantially reproduce each sample color on a selected photographic paper when the paper is exposed to the illuminant source through such filters for such exposure times;
(c) exposing the undeveloped photographic paper to the light source in sequence through each color separa-tion film and its associated group of color filters for the determined respective filter exposure times to substantially reproduce each separation film color image in the associated sample color on the photographic paper when developed, and (d) developing the exposed photographic paper to provide the pre-press color proof.
EXPOSURE TO PHOTOGRAPHIC MEDIA
Abstract of the Disclosure Pre-Press color proofing of a set of color separation films from which printing plates are to be made for color printing of a multi-color image on a paper or like printing base with a given set of printer's inks or the like, by:
(a) preparing samples of the given inks or the like on the printing base or equivalent thereof;
(b) determining the primary color component makeup of each sample in relation to a given illuminant source and from a color reference data base based on such illuminant source, determining a group of color filters and associated color filter exposure times appropriate to substantially reproduce each sample color on a selected photographic paper when the paper is exposed to the illuminant source through such filters for such exposure times;
(c) exposing the undeveloped photographic paper to the light source in sequence through each color separa-tion film and its associated group of color filters for the determined respective filter exposure times to substantially reproduce each separation film color image in the associated sample color on the photographic paper when developed, and (d) developing the exposed photographic paper to provide the pre-press color proof.
Description
~'7~B~3 Background of the Invention .... _ Field of the Invention . . _ . . _ . . .
The present invention relates in general to the field of synthesizing colors on photographic media by the successive exposure thereof to an illuminan-t source through a group of up to three color filters for selected times for each desired color. More particularly, the method of the present invention relates to the art of preparing and using a color reference diagram or like data base to assist in determining the il-lumination exposure time needed for each of up to three colorfilters for each desired colorj as disclosed in our Great Britain Patent No. 1,592,839, entitled Method of Obtaining a Target Colour On Colour Photosensitive Pho~ographic Material, and then utilizing such exposure times to produce a single sheet pre-press color proof from color separation negatives or the like.
Description of the Prior Art Conventional prior practice with respect to color proofing in the printing trade essentially involves either actual press proofing ~a procedure where actual test print-ing plates are made to literally color print the proof) or by use of primary color and black transparent overlays.
For example, 3M Company markets, un~er the trademark "Color-Key", pre-press proofing materials involving pre-sensitized ink pigment coatings, in either transparentor opaque colors, on transparent polyester base sheets.
x7~8~3 Each pi~ment coatin~ is intended -to be correla-ted with various process color printing inks. ~ach primary color and black "Color-Key" sheet is overlaid by its associated separation negative and after exposure and development, the four "Color-Key" sheets are overlaid in register to provide a "proof" or simulation of what the four-color work will look like when printed. ~lanifestly, such a pre-press proofing system, involving four overlaid sheets (which are glossy in character and which at best only indirectly match the colors of the proof with ~-he actual colors of the print-ing inks to be used) falls well short of providing the user with a fully accurate proof in the sense of the colors, color registry and texture of the color work when press printed with inks on paper.
3M Company also markets a pre-press color proofing system under the trademark "Transfer-Key", which is said to provide a complete four-color proof on a single sheet.
In this system, fac-tory pre-coated carrier sheets of color pigmentj respectively beariny cyan, yellow, magenta and black pigment, are successively manipula-ted to lamina-te each pigmen-t onto the base material by use of a proprietary laminator. Specifically, the cyan pigment is first laminated to the base material, which is then exposed to the cyan separation negative and the sheet then developed in a proprietary processor. The same exposure/development,cycle is repeated with each color, producing the four-color proof.
Pre-coated pigment carrier sheets are available only in certain colors, unless specially ordered. As manifest, such color proofing procedure, although providing a single sheet color proof, is of limited applicakility and accuracy in that ~'7~
only certain laminating pigmen-ts are available, and is inherently rather slow in cycle time in -that each pigment layer of the four-color proof must be separately and successively laminated, exposed and developed.
Another commercially available pre-press color proofing system is marketed by the duPont Company, under the trademark "Cromalin"~ In the Cromalin color proof system, dry pigment toners are factory "calibrated" to printing ink colors and each primary and black color repro-duction is on a separate sheet of photopolymer film, the films after exposure and development being laminated together in registry to provlde the color proof. The cycle time Eor this system is said to be "within an hour", rather than the hours or days required for press proofing.
Another known pre-press color proofing system which is commercially available in the Kodak Polytrans Colour Proofing Film System, such as described in "The Reproduction of Color", by R. W. G. Hunt, at page 546 (published by Fountain Press o~ Hertfordshire, England, Third Edition, 1975). In the Polytrans sys-tem screened color separation films are proofed by materials including films consisting of color-pigmented photopolymer matrices coated on a trans-parent film base. Exposure to blue or ultraviolet light hardens the photopolymer so that exposure thereof to the screened separations results in an image-wise pattern of the hardened polymer being obtained. Each exposed film is mounted on a sui-table roller and rolled under heat and pressure onto a sheet of paper, the unhardened polymer transferring to -the paper and taking the pigment with it.
Four different colors of film are used and, by exposlng each 7 ~
to the corresponding color separation positive, image-wise transfers can be obtained in each color. Each image is developed and transferred in succession, onto the paper, in register, with a color proof resulting after exposure of the transferred pigments to light. While the Polytrans system results in a color proof on a single sheet of paper, the color-pigmented photopolymer matrices used are necessarily precalibrated to printer's inks at the factory, and each color is separately and successively developed on the color proof. Registr~ of the respective color images on the paper can also prove to be a problem because the color images are applied to the paper by successive roller transfer.
Brief Summary of the Invention In general, the present invention involves the method of obtaining the color proofing target colors from an illuminant source on a single sheet of photographic media or the like by preparing a color reference diagram or like data base characteristic of a given illuminant source (in the manner taught by our aforementioned Great Britain Patent No. 1,592,839; using the color reference da~a base to aid in determining the exposure times -to use with each of up to three color filters for each target color; exposi,ng the photographic media through the color filters for their respective exposure times; and then developing the exposed photographic media to produce a pre-press color proof.
Another characteristic of the present invention is the providing of a relatively simple, inexpensive method of -? -5-~7~8~3 synthesizing color proofing target colors by sequentially exposing a photographic media to llght of different colors which is extxacted from an illuminan-t source by color filters and which is applied to selected porti~ns of the photo-graphic media, as by sequen-tial exposure through a set of color separation ~ilms.
Further objects and features of the present invention involve the development and use of a color reference data base for accurate color reproduction of color proofing target colors on photographic print media by use of an illuminant source and sets of color filters, which data include and interrelate (1) the chromaticity coordinates, dominant wavelength, and saturation percentages for each possible target color in relation to the given illuminant source, and ~2) the chromaticity coordinates and filter percentage characteristic of each filter for each target color in relation to the illuminant source. Optionally, the data can also include, or can in part be expressed in terms of target color densities, i.e. the gray level and the proportionate levels of red, yellow and blue in each target color.
More specifically, it is an object and feature of the present invention to provide a method whereby pre-press color proofs may be rapidly, economically and accurately prepared on a single sheet of opaque photographic paper to show what the color reproduction will be like when printed using a given set of printer's inks and plates prepared from a given set of color separation films, -the color proofing technique of the present invention offering the unique advantage of being able to directly utilize swatches of the actual prin-ter's inks as targe-t colors in -the process and requiring only a single s-tep of photographic media develop-ment rather -than separate development s-teps for each color, as is characteristic of prior art pre-press proofing sys-tems.
The technique of the present invention realizes marked improvement in color proofing cycle time. The apparent capability of the present process in this respect is a cycle time of about fifteen minutes or even less, as com-pared with a cycle time of about an hour for previously known pre-press proofing processes, and as compared with a cycle time of at least several hours when using con-ventional press proofing techniques.
These and other objects, features, advan-tages and characteristics of the method of my present invention will be apparent from the following detailed description of the preferred embodiments thereof in which reference is made to the accompanying figures.
Brief Description Of The Drawings FIG. 1 is a block diagram outlining typical appli-cation of the present invention to pre-press color proofing.
FIG. 2 is a block diagram outlining a typical color printing procedure including the production of a color proof from a given set of four-color separation films and a given set of printer's inks and printer's paper or the like, in accordance with the present invention.
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Description of the Preferred Embodiments The present invention i5 in some respects an application and improvement of the target color reproduction method disclosed in our a~orementioned Great Britain Patent No.
1,592,839. For discussion purposes, a brief overview of such target color reproduction method is set forth below, along with a discussion of some of the method's underlying prlnciples .
Preliminarily, it may be assumed that every color visible to the human eye is composed entirely o red, green and/or blue components. Thus, it fcllows that any such color may be synthesized by the proper additive mixing of red, green and blue lights. However, the problem remains of how to determine what are the red, green and blue components of a given tar~et color, and how to select and use color filters which will extract the proper amounts of red, green and blue light from a given illuminant source to reproduce that color on the particular photographic media being used.
Since, as has been explained, the color temperature of the illuminant source is a basic factor which must be considered, the starting point ~or a given target color reproduction is to determine the Kelvin temperature o~ the illuminant source which will be used to produce the target color. Having determined the color temperature of the illuminant source, it may then be located as by plotting thereof on a data base such as a CI~ diagram working area.
Next, the target color data point is determined in the data base working area ~or the color to be achieved.
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This is done by comparing the target color to a color reference data base which was prepared with an illuminant source having the same color -temperature and spectral distribution as the illuminant source being used -to produce the target color. The location of the closest matching color on the data base, e.g. the coordinates of the matching color on -the color reference diagram is taken to be that of the target color.
Then, a set of three filters is selected which can be used to produce the particular target color. Filter triangle plots, or data base equivalent ~hereof, are then delineated and any set of three filters may be used which defines a Eilter triangle or equivalent coincident with the location of the target color. This is because, when considering photographic media, a set of three filters may be used to produce any color located within or on the filter triangle they define.
Once the red, green and blue components (x, y and z) of the target color and of each of the three color filters are known, a determination is made as to how much of each color filter is needed in order to produce the target color.
This is done by determining what percentage of each color filter (i.e. what filter percentage) is needed to achieve a result such that the sums of their red, green and blue contributions equal, respectively, the red, green and blue components of the target color.
Each filter's exposure time is next determined by multiplying its respective saturation time by its respective filter percentage. Finally, the particular, positive photo-graphic media being used is exposed sequentially to theilluminant source through each color filter for its respective ~'7~8~
exposure time. Upon developing the photographic media in accordance with the manufacturer's instructions, the target color is produced on the developed positive photographic media.
To further illustrate the significant features of our earlier disclosed target color reproduction method, the following detailed example thereof is presented. A
swatch of a bluish color was chosen to be the color for reproduction, i.e. as the target color.
A color reference data base in the form of a CIE
diagram was produced according to the procedure set forth in our said Great Britain Patent No. 1,592,833, with the same illuminant source as that of the illuminant source being used to prepare the target color (tungsten at 3050 K.).
Then, the target color was compared to the color reference data base and it was noted that the x, y coordinates of the closest matching color thereon were x(red) = .211 and y(green) = .3425. Using these coordinates, a point for the target color was plotted on the working diagram. In connection with the working diagram it will be understood that such a diagram may be of the CIE type or may be any Cartesian coordinate system or equivalent data base, such as a computer program, having units which can be correlated with those used in a standard, CIE diagram. For example, a known data system involving programming a digital computer to determine CIE
coordinates from spectro-photometric data is disclosed by J. E. McCarley et al. in an article entitled "Digital System for Converting Spectro-photometric Data to CIE Coordinates, Dominant Wavelength and Excitation Purity, at 55 Journal of The Optical Society of America, pp 355-360 (April, 1965).
Other data systems known per se may also be used without departing from the scope of the present invention.
, --1 0--In the example being discussed, three color filters Kodak (trade mark) Wratten Photomechanical filters 25 (red), 58 (green) and 47B (blue) were selected and located in the data base, either by use of the manufacturer's reference data, or by use of a spectrophotometer, or by direct comparison of the colored filters to the color reference diagram to find the coordinates of the closest matching color thereon, for example.
For the three filters selected, the following coordinates were supplied by the manufacturer:
Filter x (red) y (green) z (blue) 25 (red) .6850 . 3147 . 0003 58 (green) .2693 .6831 .0476 ~7B (blue) .1554 .0220 .8226 The saturation time for each color filter was determined for the particular, positive photographic paper being used Kodak (trade mark) Ektachrome (trade mark) RC paper type 1993, manufactured by Eastman Kodak Company. In the example selected, the saturation times for the red, green and blue filters were found to be, respectively, 35.3 seconds, 37 seconds and 20.1 seconds.
Afte the saturation times have been determined for each filter, a final check on the accuracy of the result can be made by trial production of a gray at the plotted point for the illuminant source. Whether a gray has been achieved may be checked, for example, by comparing the resulting color with a standard reference work such as the True Color Process Guide, published by Krug Litho Art Co~, of Kansas City, Missouri, or by checking the sample on a reflective digital densitometer such as a GAM Model 126P, available from the Graphic Arts Manufacturing Company. If it i5 , . ~
found that a ~ray has not been achieved, the dominant color(s) are observed and the exposure time(s) for the fil-ter(s) are adjusted, as is known to those skilled in the ar-t, until a gray is obtained.
Next, the filter percentayes for the red, green and blue filters, in relation to the target color were found to be 0%, 48.1%, 51.9%, respectively. These filter percen-tages (the proportiona-te filter exposures necessary to essentially reproduce the target color from the filter colors) can be obtained by interpolatively correlating the target color coordinates and the filter color coordinates.
Thus, for example, the dominant filter 47B (blue) can be expected to provide the dominant target color component (z coordinate .4465) and will approximately do so at a filter percentage of 52% (.4465 - .42775 = .01875 error). Similarly, the second significant color coordinate of the target color (y coordinate .3425) can be provided primarily by the filter 58 (green) which it will approximate at a filter percentage of 48%, taking into account the y component (yreen) contri-bution (.0114) of -the 47B filter (blue) (.3425 - .0114 - .3279 = .0032 error), with this filter 58 (green) also substantially providing the third target color component (x coordinate .2110) at the same filter percentage along with the x (red) component contribution (.0808) of the 47B filter (.2110 - .0808 - .1293 = .0009 error), and making a z component (blue) contribution (.02285) reducing the blue error in -the 47B and 58 filter contributions (.01875 - .02285 = -.0041 error). Refinement of the interpolations results in the indicated respective filter percentages for the selected filters, in relation to the selected target color, of 0% for the 25 fil-ter (red), 48.1 for the 58 filter (green), and 51.9% for the 47B Eilter (blue).
By multiplying the red, green and blue filters' respective filter percentages by their respective saturation ~imes, the desired exposure times for the respective filters were found to be 0 seconds, 17.8 seconds, and 10~4 seconds, respectively.
The undeveloped photographic paper is then exposed to the illuminant source through each of the up to three color filters for its respective exposure time. After the last exposure is madej the positive photographic media is developed in accordance with the manufacturer's instructions, with the result that the target color is obtained on the developed photographic paper.
A technique important to practical target color repro-duction involves the determination of saturation time for a particular gray level, since this gives the base time for all colors on that level. This determination is made as follows:
A trial exposure is made for a gray sample, using any combination of up to three ~ilters, but the filter combination should be such as io produce a color balance of 1/3 each of cyan, magenta and yellow. The exposed sample, which involved negative print paper Kodak (trade mark) 37 RC as a further illustrative example, is then measured with a densitometer or like instrument (spec-trophotometer or colorimeter) -that identifies balance of cyan, magenta and yellow, i.e. the grayness of the sample. In the case where a densitometer is used for this measurement, four readouts are given by the instrument. As an example~
the gray level of the sample may be 70 and the color aensities may be cyan 65, magenta 72 and yellow 59. By adding these three densities, a total of 196 results. Since a color balance is desired, i.e. a relative density of .33 .33 .33 of a density of 65 65 65, we note that the density balance in the selected example is 33% for cyan, 37% for magenta and 30% for yellow.
In the instance of this example, these colors were obtained through the complementary filters Wratten 25, 58 and 47-B, ;~ r 13 for cyan, magen-ta and yellow. Subtracting the percent difference for each color, i-t is no-ted that cyan at 33~
requires no correction, the magenta requires a reduction of -4~ and yellow requires an increase of +3%. At this point a correction factoring system is employed to make a new exposure. In the correction system adopted in this example, -the correcting number (on a geometric progression scale) to reduce the magenta density by 4% is .9120. This number is then multiplied by the original exposure -time, which gives a new time for the magenta exposure. Correspondingly, yellow is 3~ under so the correction factor in this instance would be 1.072 to give the new exposure time for yellow.
If it is preferred that the gray level be a differen-t figure, say 66 by way of example, instead of 70, the correction figure to arrive at the preferred gray level is .942857, applicable to all exposure times. Another sample is exposed, using the revised exposure times and the correc-tion procedure is repeated if necessary until the desired gray balance and gray level are achieved. Once these exposure times are obtained it is next desirable to find -the saturati.on time for that level for all colors. With the correct gray exposure time at hand, the three exposure times are divided by the correct "percentage of filter" amounts for gray, as determined from the chromatici-ty data base for the illuminant point, as earlier discussed.
Taking the "percentage of filter" amounts for the illuminant point, these figures are divided into the new times for gray and this determines the satura-tion times for this particular level of the chroma-ticity diagram for all colors. Using this time, any color can be achieved ,y multip:lying its "percentage of f'ilter" amount by the s~turation time.
To iLlustrate this technique, and using the example initially discussed earller, the following measure-ments and calculations occur:
1. Time used 10.1 sec. for the 25 filter (for cyan) 4.2 sec. for -the 58 filter ~for magenta)
The present invention relates in general to the field of synthesizing colors on photographic media by the successive exposure thereof to an illuminan-t source through a group of up to three color filters for selected times for each desired color. More particularly, the method of the present invention relates to the art of preparing and using a color reference diagram or like data base to assist in determining the il-lumination exposure time needed for each of up to three colorfilters for each desired colorj as disclosed in our Great Britain Patent No. 1,592,839, entitled Method of Obtaining a Target Colour On Colour Photosensitive Pho~ographic Material, and then utilizing such exposure times to produce a single sheet pre-press color proof from color separation negatives or the like.
Description of the Prior Art Conventional prior practice with respect to color proofing in the printing trade essentially involves either actual press proofing ~a procedure where actual test print-ing plates are made to literally color print the proof) or by use of primary color and black transparent overlays.
For example, 3M Company markets, un~er the trademark "Color-Key", pre-press proofing materials involving pre-sensitized ink pigment coatings, in either transparentor opaque colors, on transparent polyester base sheets.
x7~8~3 Each pi~ment coatin~ is intended -to be correla-ted with various process color printing inks. ~ach primary color and black "Color-Key" sheet is overlaid by its associated separation negative and after exposure and development, the four "Color-Key" sheets are overlaid in register to provide a "proof" or simulation of what the four-color work will look like when printed. ~lanifestly, such a pre-press proofing system, involving four overlaid sheets (which are glossy in character and which at best only indirectly match the colors of the proof with ~-he actual colors of the print-ing inks to be used) falls well short of providing the user with a fully accurate proof in the sense of the colors, color registry and texture of the color work when press printed with inks on paper.
3M Company also markets a pre-press color proofing system under the trademark "Transfer-Key", which is said to provide a complete four-color proof on a single sheet.
In this system, fac-tory pre-coated carrier sheets of color pigmentj respectively beariny cyan, yellow, magenta and black pigment, are successively manipula-ted to lamina-te each pigmen-t onto the base material by use of a proprietary laminator. Specifically, the cyan pigment is first laminated to the base material, which is then exposed to the cyan separation negative and the sheet then developed in a proprietary processor. The same exposure/development,cycle is repeated with each color, producing the four-color proof.
Pre-coated pigment carrier sheets are available only in certain colors, unless specially ordered. As manifest, such color proofing procedure, although providing a single sheet color proof, is of limited applicakility and accuracy in that ~'7~
only certain laminating pigmen-ts are available, and is inherently rather slow in cycle time in -that each pigment layer of the four-color proof must be separately and successively laminated, exposed and developed.
Another commercially available pre-press color proofing system is marketed by the duPont Company, under the trademark "Cromalin"~ In the Cromalin color proof system, dry pigment toners are factory "calibrated" to printing ink colors and each primary and black color repro-duction is on a separate sheet of photopolymer film, the films after exposure and development being laminated together in registry to provlde the color proof. The cycle time Eor this system is said to be "within an hour", rather than the hours or days required for press proofing.
Another known pre-press color proofing system which is commercially available in the Kodak Polytrans Colour Proofing Film System, such as described in "The Reproduction of Color", by R. W. G. Hunt, at page 546 (published by Fountain Press o~ Hertfordshire, England, Third Edition, 1975). In the Polytrans sys-tem screened color separation films are proofed by materials including films consisting of color-pigmented photopolymer matrices coated on a trans-parent film base. Exposure to blue or ultraviolet light hardens the photopolymer so that exposure thereof to the screened separations results in an image-wise pattern of the hardened polymer being obtained. Each exposed film is mounted on a sui-table roller and rolled under heat and pressure onto a sheet of paper, the unhardened polymer transferring to -the paper and taking the pigment with it.
Four different colors of film are used and, by exposlng each 7 ~
to the corresponding color separation positive, image-wise transfers can be obtained in each color. Each image is developed and transferred in succession, onto the paper, in register, with a color proof resulting after exposure of the transferred pigments to light. While the Polytrans system results in a color proof on a single sheet of paper, the color-pigmented photopolymer matrices used are necessarily precalibrated to printer's inks at the factory, and each color is separately and successively developed on the color proof. Registr~ of the respective color images on the paper can also prove to be a problem because the color images are applied to the paper by successive roller transfer.
Brief Summary of the Invention In general, the present invention involves the method of obtaining the color proofing target colors from an illuminant source on a single sheet of photographic media or the like by preparing a color reference diagram or like data base characteristic of a given illuminant source (in the manner taught by our aforementioned Great Britain Patent No. 1,592,839; using the color reference da~a base to aid in determining the exposure times -to use with each of up to three color filters for each target color; exposi,ng the photographic media through the color filters for their respective exposure times; and then developing the exposed photographic media to produce a pre-press color proof.
Another characteristic of the present invention is the providing of a relatively simple, inexpensive method of -? -5-~7~8~3 synthesizing color proofing target colors by sequentially exposing a photographic media to llght of different colors which is extxacted from an illuminan-t source by color filters and which is applied to selected porti~ns of the photo-graphic media, as by sequen-tial exposure through a set of color separation ~ilms.
Further objects and features of the present invention involve the development and use of a color reference data base for accurate color reproduction of color proofing target colors on photographic print media by use of an illuminant source and sets of color filters, which data include and interrelate (1) the chromaticity coordinates, dominant wavelength, and saturation percentages for each possible target color in relation to the given illuminant source, and ~2) the chromaticity coordinates and filter percentage characteristic of each filter for each target color in relation to the illuminant source. Optionally, the data can also include, or can in part be expressed in terms of target color densities, i.e. the gray level and the proportionate levels of red, yellow and blue in each target color.
More specifically, it is an object and feature of the present invention to provide a method whereby pre-press color proofs may be rapidly, economically and accurately prepared on a single sheet of opaque photographic paper to show what the color reproduction will be like when printed using a given set of printer's inks and plates prepared from a given set of color separation films, -the color proofing technique of the present invention offering the unique advantage of being able to directly utilize swatches of the actual prin-ter's inks as targe-t colors in -the process and requiring only a single s-tep of photographic media develop-ment rather -than separate development s-teps for each color, as is characteristic of prior art pre-press proofing sys-tems.
The technique of the present invention realizes marked improvement in color proofing cycle time. The apparent capability of the present process in this respect is a cycle time of about fifteen minutes or even less, as com-pared with a cycle time of about an hour for previously known pre-press proofing processes, and as compared with a cycle time of at least several hours when using con-ventional press proofing techniques.
These and other objects, features, advan-tages and characteristics of the method of my present invention will be apparent from the following detailed description of the preferred embodiments thereof in which reference is made to the accompanying figures.
Brief Description Of The Drawings FIG. 1 is a block diagram outlining typical appli-cation of the present invention to pre-press color proofing.
FIG. 2 is a block diagram outlining a typical color printing procedure including the production of a color proof from a given set of four-color separation films and a given set of printer's inks and printer's paper or the like, in accordance with the present invention.
'7~
Description of the Preferred Embodiments The present invention i5 in some respects an application and improvement of the target color reproduction method disclosed in our a~orementioned Great Britain Patent No.
1,592,839. For discussion purposes, a brief overview of such target color reproduction method is set forth below, along with a discussion of some of the method's underlying prlnciples .
Preliminarily, it may be assumed that every color visible to the human eye is composed entirely o red, green and/or blue components. Thus, it fcllows that any such color may be synthesized by the proper additive mixing of red, green and blue lights. However, the problem remains of how to determine what are the red, green and blue components of a given tar~et color, and how to select and use color filters which will extract the proper amounts of red, green and blue light from a given illuminant source to reproduce that color on the particular photographic media being used.
Since, as has been explained, the color temperature of the illuminant source is a basic factor which must be considered, the starting point ~or a given target color reproduction is to determine the Kelvin temperature o~ the illuminant source which will be used to produce the target color. Having determined the color temperature of the illuminant source, it may then be located as by plotting thereof on a data base such as a CI~ diagram working area.
Next, the target color data point is determined in the data base working area ~or the color to be achieved.
.~ .
This is done by comparing the target color to a color reference data base which was prepared with an illuminant source having the same color -temperature and spectral distribution as the illuminant source being used -to produce the target color. The location of the closest matching color on the data base, e.g. the coordinates of the matching color on -the color reference diagram is taken to be that of the target color.
Then, a set of three filters is selected which can be used to produce the particular target color. Filter triangle plots, or data base equivalent ~hereof, are then delineated and any set of three filters may be used which defines a Eilter triangle or equivalent coincident with the location of the target color. This is because, when considering photographic media, a set of three filters may be used to produce any color located within or on the filter triangle they define.
Once the red, green and blue components (x, y and z) of the target color and of each of the three color filters are known, a determination is made as to how much of each color filter is needed in order to produce the target color.
This is done by determining what percentage of each color filter (i.e. what filter percentage) is needed to achieve a result such that the sums of their red, green and blue contributions equal, respectively, the red, green and blue components of the target color.
Each filter's exposure time is next determined by multiplying its respective saturation time by its respective filter percentage. Finally, the particular, positive photo-graphic media being used is exposed sequentially to theilluminant source through each color filter for its respective ~'7~8~
exposure time. Upon developing the photographic media in accordance with the manufacturer's instructions, the target color is produced on the developed positive photographic media.
To further illustrate the significant features of our earlier disclosed target color reproduction method, the following detailed example thereof is presented. A
swatch of a bluish color was chosen to be the color for reproduction, i.e. as the target color.
A color reference data base in the form of a CIE
diagram was produced according to the procedure set forth in our said Great Britain Patent No. 1,592,833, with the same illuminant source as that of the illuminant source being used to prepare the target color (tungsten at 3050 K.).
Then, the target color was compared to the color reference data base and it was noted that the x, y coordinates of the closest matching color thereon were x(red) = .211 and y(green) = .3425. Using these coordinates, a point for the target color was plotted on the working diagram. In connection with the working diagram it will be understood that such a diagram may be of the CIE type or may be any Cartesian coordinate system or equivalent data base, such as a computer program, having units which can be correlated with those used in a standard, CIE diagram. For example, a known data system involving programming a digital computer to determine CIE
coordinates from spectro-photometric data is disclosed by J. E. McCarley et al. in an article entitled "Digital System for Converting Spectro-photometric Data to CIE Coordinates, Dominant Wavelength and Excitation Purity, at 55 Journal of The Optical Society of America, pp 355-360 (April, 1965).
Other data systems known per se may also be used without departing from the scope of the present invention.
, --1 0--In the example being discussed, three color filters Kodak (trade mark) Wratten Photomechanical filters 25 (red), 58 (green) and 47B (blue) were selected and located in the data base, either by use of the manufacturer's reference data, or by use of a spectrophotometer, or by direct comparison of the colored filters to the color reference diagram to find the coordinates of the closest matching color thereon, for example.
For the three filters selected, the following coordinates were supplied by the manufacturer:
Filter x (red) y (green) z (blue) 25 (red) .6850 . 3147 . 0003 58 (green) .2693 .6831 .0476 ~7B (blue) .1554 .0220 .8226 The saturation time for each color filter was determined for the particular, positive photographic paper being used Kodak (trade mark) Ektachrome (trade mark) RC paper type 1993, manufactured by Eastman Kodak Company. In the example selected, the saturation times for the red, green and blue filters were found to be, respectively, 35.3 seconds, 37 seconds and 20.1 seconds.
Afte the saturation times have been determined for each filter, a final check on the accuracy of the result can be made by trial production of a gray at the plotted point for the illuminant source. Whether a gray has been achieved may be checked, for example, by comparing the resulting color with a standard reference work such as the True Color Process Guide, published by Krug Litho Art Co~, of Kansas City, Missouri, or by checking the sample on a reflective digital densitometer such as a GAM Model 126P, available from the Graphic Arts Manufacturing Company. If it i5 , . ~
found that a ~ray has not been achieved, the dominant color(s) are observed and the exposure time(s) for the fil-ter(s) are adjusted, as is known to those skilled in the ar-t, until a gray is obtained.
Next, the filter percentayes for the red, green and blue filters, in relation to the target color were found to be 0%, 48.1%, 51.9%, respectively. These filter percen-tages (the proportiona-te filter exposures necessary to essentially reproduce the target color from the filter colors) can be obtained by interpolatively correlating the target color coordinates and the filter color coordinates.
Thus, for example, the dominant filter 47B (blue) can be expected to provide the dominant target color component (z coordinate .4465) and will approximately do so at a filter percentage of 52% (.4465 - .42775 = .01875 error). Similarly, the second significant color coordinate of the target color (y coordinate .3425) can be provided primarily by the filter 58 (green) which it will approximate at a filter percentage of 48%, taking into account the y component (yreen) contri-bution (.0114) of -the 47B filter (blue) (.3425 - .0114 - .3279 = .0032 error), with this filter 58 (green) also substantially providing the third target color component (x coordinate .2110) at the same filter percentage along with the x (red) component contribution (.0808) of the 47B filter (.2110 - .0808 - .1293 = .0009 error), and making a z component (blue) contribution (.02285) reducing the blue error in -the 47B and 58 filter contributions (.01875 - .02285 = -.0041 error). Refinement of the interpolations results in the indicated respective filter percentages for the selected filters, in relation to the selected target color, of 0% for the 25 fil-ter (red), 48.1 for the 58 filter (green), and 51.9% for the 47B Eilter (blue).
By multiplying the red, green and blue filters' respective filter percentages by their respective saturation ~imes, the desired exposure times for the respective filters were found to be 0 seconds, 17.8 seconds, and 10~4 seconds, respectively.
The undeveloped photographic paper is then exposed to the illuminant source through each of the up to three color filters for its respective exposure time. After the last exposure is madej the positive photographic media is developed in accordance with the manufacturer's instructions, with the result that the target color is obtained on the developed photographic paper.
A technique important to practical target color repro-duction involves the determination of saturation time for a particular gray level, since this gives the base time for all colors on that level. This determination is made as follows:
A trial exposure is made for a gray sample, using any combination of up to three ~ilters, but the filter combination should be such as io produce a color balance of 1/3 each of cyan, magenta and yellow. The exposed sample, which involved negative print paper Kodak (trade mark) 37 RC as a further illustrative example, is then measured with a densitometer or like instrument (spec-trophotometer or colorimeter) -that identifies balance of cyan, magenta and yellow, i.e. the grayness of the sample. In the case where a densitometer is used for this measurement, four readouts are given by the instrument. As an example~
the gray level of the sample may be 70 and the color aensities may be cyan 65, magenta 72 and yellow 59. By adding these three densities, a total of 196 results. Since a color balance is desired, i.e. a relative density of .33 .33 .33 of a density of 65 65 65, we note that the density balance in the selected example is 33% for cyan, 37% for magenta and 30% for yellow.
In the instance of this example, these colors were obtained through the complementary filters Wratten 25, 58 and 47-B, ;~ r 13 for cyan, magen-ta and yellow. Subtracting the percent difference for each color, i-t is no-ted that cyan at 33~
requires no correction, the magenta requires a reduction of -4~ and yellow requires an increase of +3%. At this point a correction factoring system is employed to make a new exposure. In the correction system adopted in this example, -the correcting number (on a geometric progression scale) to reduce the magenta density by 4% is .9120. This number is then multiplied by the original exposure -time, which gives a new time for the magenta exposure. Correspondingly, yellow is 3~ under so the correction factor in this instance would be 1.072 to give the new exposure time for yellow.
If it is preferred that the gray level be a differen-t figure, say 66 by way of example, instead of 70, the correction figure to arrive at the preferred gray level is .942857, applicable to all exposure times. Another sample is exposed, using the revised exposure times and the correc-tion procedure is repeated if necessary until the desired gray balance and gray level are achieved. Once these exposure times are obtained it is next desirable to find -the saturati.on time for that level for all colors. With the correct gray exposure time at hand, the three exposure times are divided by the correct "percentage of filter" amounts for gray, as determined from the chromatici-ty data base for the illuminant point, as earlier discussed.
Taking the "percentage of filter" amounts for the illuminant point, these figures are divided into the new times for gray and this determines the satura-tion times for this particular level of the chroma-ticity diagram for all colors. Using this time, any color can be achieved ,y multip:lying its "percentage of f'ilter" amount by the s~turation time.
To iLlustrate this technique, and using the example initially discussed earller, the following measure-ments and calculations occur:
1. Time used 10.1 sec. for the 25 filter (for cyan) 4.2 sec. for -the 58 filter ~for magenta)
2.4 sec. for the 47-B filter ~or yellow) 2. Sample measured 70) 65 72 59
3. 65-~72~59 = 196 65/196 - 33% 72/196 7 37% 59/197 = 306
4.NEED 33%NEED 33%NEED 33%
HAVE 33OHAVE 37~ H~VE 30%
0 + 4% - 3%
HAVE 33OHAVE 37~ H~VE 30%
0 + 4% - 3%
5.-6. .9120 1.072 X 4.2 X 2.4 10.1 3.8 2.6 NEW TI.~E
7. NEED . 66 gray level HAVE . 70 " " .66/.70 = .942857 10.1 3.8 2.6 X.942~57 X.942857 X.942857 9.5 3.6 2.4 NEW TIMES for .66 gray 10. Assuming that -these'times for gray are correc-t, the following SATUR~TION TIMES FOR the .66 level of the chromaticity diagram evolve, using the given photo-graphic media used in the example:
9.5/.443458 = 21.4 sec. 3.6/.379670 = 9.4 sec.
2.4/.176872 = 13.56 sec.
Any color can now be exposed for,using these times.
the complement of Thus, for/a dominant wavelength of 410 at the 90% saturation level from the illuminant, can be computed by .083369 .003930 .912701 X21.4 X 9 4 X 13 45 1.8 ~ 04 12.3 As will be evident, the determinations and operations of the exposure equipment can also be accomplished by computer, utilizing programming techniques known per se. In one pro-to-7~
type equipment at hand, an Apple II (trade mark) computer i5 used with a so-called ~, y table to horizontally move -the photo-~raphic media under a stati~nary mask opening through which the media is ill~lminated downwardly from a stationary illuminant source through selected filters. The computer also inter-faces with exposure control mechanism, i.e. the light source and filters. In the phototype arrangement a computer is used with a color TV monitor. All necessary computations to provide the color reference data base for the light source and filters are programmed into the computer in a manner known per se. The photographic media is moved on the x, y table under control of the computer so that the desired exposure point is directly in line with the mask openiny and the light source. Filters are moved into line with the illuminant source sequentially and exposure times are also controlled by the computer to reproduce any desired target color in the manner characteristic of the present invention.
Repeated exposure to develop an array of target colors can result in an entire data base working area being produced~
As earlier indicated, the present invention lnvolves the application of the foregoing target color reproduction method to the field of color printing and specifically to the proofing, prior to the making of printing plates, of the so-called color separation components (film negatives or positives) from which the plates are to be made. Given a set of color separation films and a given set of printer's inks (e.g. yellow, magenta, cyan and black), the present invention provides, through use of photographic printing techniques, a simple and accurate way of determining what 7~
printed color reproductions will look like without actually having to prepare test printing plates. More specifically, the present invention provides a simple and straightforward pre-press color proofing technique whereby a given set of color separation components is "proofed" on photographic paper in a manner showing what the printed color reproduction will be like if printed with a given set of printer's inks, the color proof being "printed" by use of a light source and color filters rather than by use of the inks, with filtered light exposure times coordinated to the ink colors.
In making of color proofs from color separation com-ponents in a manner according to the present invention, each separation component (which is a black film base, positive or negative), may be considered simply as a mask con-trolling the areas or portions of the photographic print paper which are exposed to selected sets of filters for selected times simulating the color composition of the inks. ~y this technique, the "printing" of the photographic paper is ac-complished by light in essentially the same manner as a printer would print with inks, i.e. with all colors "printed" on a single non-transparent sheet of paper, as distinguished from conventional color proofing techniques which commonly involve each primary color and black being developed on separate transparent sheets which are superimposed to simulate'the final printed reproductions.
As a specific example of application of the present invention, it will be understood at the outset tha-t color separation components, as made or available in -the color print-ing field, are derived in a number of ways, such as through a j, ,;
~ 17-camera process, conventional per se, which provides four color separation films, each of which in appearance is a black film base, positive or negative, but which constitutes respective records of the yellow content, -the magenta con-tent, the cyan content, and the black con-tent of the original.
Each such black base film is in effect a mask made of more or less microscopic dots or continuous tone which either parti-ally pass (a negative film) or partially block ~a positive film) light in the course of preparing the corresponding color printing plate to be used in the final printing process.
Each such "dot" or "tone" of the printing plate permits more or less of the corresponding ink to be applied to the paper on which the printed color reproduction is printed.
As diagrammatically illustrated in FIG. 1, to obtain a color proof of what the printed color reproduction will be, using a given set of inks and a given set of color separation components, the printer or color proofer, in utilizing the concepts of the present invention, first makes so-called "draw down" samples of the four inks on the paper or like base which is identical to or at least similar in color and texture to the paper or base on which the printing run is to be made. These are simply samples or "swatches" of the yellow, magenta, cyan and black inks which the printer has tentatively selected for the printing. Each ink s,watch thus produced is then subjected to color analysis, as by comparison with a color reference data base developed and applied as taught by our aforementioned Great Britain Patent No. 1,592,839 to determine in each instance the red, green and blue components thereof, and up to ~hree color filters are selected in each instance from which the color of each ^; -18-ink swatch, as a color proofing target color, can be reproduced from a given light source. As will be understood, with a given light source and with four swatches of a selected set of ink candidates (yellow, magenta, cyan and black), the analysis technique of the present invention provides the color proofer with information as to the identity of each of the up to three color filters to be used in the reproduction of each of the four target colors (the ink swatches), and the light source exposure times to be used with each of the color filters to reproduce each of the four target colors.
With this information at hand, a selected photographic print paper (such as Kodak (trade mark) Ektacolor (-trade mark) RC 74 negative print papex, for example) is placed on pins in the exposure plane associated with the light source and filters (the pins matching pin holes in the separation films). The first (e.g. yellow) separation film is then placed on the un-exposed photographic print paper and the light source and first group of filters (e.g. the yellow group) ar~ controlled to expose the photographic print paper and first (e.g. ~ellow) separation film to the light source in sequence through the associated up to three filters for the determined illumination times to re-produce the first ink target color image on the photographic paper when the paper is developed. The first separatlon film is then removed from the print paper, the second separation film (e.g. magenta) is superimposed on the paper, and the exposure process is repeated using the second group of up to three filters te.g. the magenta group) and the associated exposure times determined for the second (e.g. magenta) ink swatch. The second separation film is then removed from the . ... .
~73~8~
photographic paper and the third (e.g. cyan) separation film superimposed thereon, with the e~posure sequence again repeated using -the up to three color fil-ters of the third group of fil-ters (e.g. the cyan group) and the associated exposure -times determined from the target color analysis of the third (e.g. cyan) ink swatch. The third separation film is -then removed from the photographic paper and the fourth separation film (e.g. black) superimposed thereon, with the exposure sequence again being repeated with the up to three color filters of the fourth group of filters (e.g. the black group~ and the associated exposure times determined for the fourth (e.g. black) ink target color swatch.
The resulting photographic paper, thus exposed, is developed in the conventional manner, and the resulting developed print is an image-wise color proof on a single sheet of opaque paper, accurately showing the color proofer what the finished printed color material will look like when printed on the selected paper by use of the selected inks and printing plates prepared from the selected separation films, it being significant in this respect that the color proof is thus produced without test plates and wi-thout ac-tual use (beyond the preparation of the original ink swatches) of the inks to be used on the paper to be used in the final 25 color printing. `
As a specific example of practice of the present invention, a set of color separation films was prepared from a graphic art overlay of a ci-ty tourist map and related text material. The separa-tion films were produced by compositing various screen effects into four color separation negatives in a known manner. ~pecifically, various color effects were developed on GAF (trade mark) P4 20x24" line negative film, following which the color ef~ects were composited on GAF (trade mark) HD 403 duplicating film ~or the four color separation negative films. Target color samples were obtained from the prin~er on coated web stock white paper (50 lb.) which were draw downs of the four inks to be used in the printing of the maps, namely, Acme Temp (trade mark) Yellow M-76325-A, ~cme Temp (trade mark~ ~roc. Warm Red M-79535, Acme Temp (trade mark) Blue M-76326 and Acme Temp (trade mark) Black M-76990. The available illuminant light source was a GE tungsten map lamp rated at 100 watts at 20 volts, and the temperature thereof was measured to be 3050 Kelvin by a Gossen (trade mark) color temperature meter. The primary color components of the various samples were then measured by a GAM (trade mark) reflection densitometer, Model GAM 126P.
The yellow ink sample was found to have a gray level of 13, a density (proportiona~ percentage) of 23 (13.6%) for blue, 30 (17.8%) for magenta, and 116 (68.6%) for yellow. The magenta or warm red sample was found to have a gray level of 45, a density of 29 (11.3%) for blue, 134 (52.3%) for mayenta, and 93 (36.3%) for yellow. The cyan or blue sample was found to have a gray level of 96, a density of 151 (60.2~) for blue, 64 (25.5~ for magenta, and 36 (14.3%) for yellow. The black ink sample was found to have a gray level of 189, a density of 193 (33.2%) for blue, 193 (33.2%) for magenta, and 196 (33.6%) for yellow.
The x, y and z coordinates of the ink samples were determined by reference to a data base (as in our Great Britain Patent No. 1,592,839), or such can be determined directly by use of a spectrophotometer, as follows:
,,r.~g ~ 21-7~8~3 Ink Sample x y z yellow .4973 .4614 .0275 magenta .6107 .3312 .0579 cya~ .2245 .3193 .4560 black .4597 .4063 .1338 In this example, the filters chosen were the same as employed in the earlier example set forth, namely Kodak (trade mark) Wratten Photomechanical Filters Numbers 25 (red), 58 (green), and ~7B (blue). In this example, the selected undeveloped photographic paper was Kodak (trade mark) Ektacolor ~trade mark) RC 78, type NRC, manufactured by the Eastman Kodak Company. For this paper, the saturation times, adjusted as to each gray level, were determined as earlier set forth, for the red, green and blue filters, to be:
Filter 25 Filter 58Filter 47B
(red) (green) (blue) .. . . __ For gray level:
13 (yellow) 3.5 sec. 8.2 18.3 45 (magenta) 41.8 28.3 63.5 2096 (cyan 89.2 60.4 135.4 189 (black) 175.6 118.9 266.7 From the determined information as to the color component makeup of the samples, the characteristics of the available primary color filters, and the nature and saturation times of the given photographic paper in relation to the ,~ r 22 filters and illuminant source, the corresponding exposure times to substantially reproduce each target color on the photographic paper were determined, with reference to the color reference data base, to be:
Exposure Exposure Exposure Exposure of yellow of magenta of cyan of black separation separation separation separation film film film film Filters 25 (red) 0.2 sec. none 103.7 85.7 58 (green) none 53.0 5.9 52.6 47B ~blue) 36.3 19.0 4.2 46.1 To extend the exposure times for improved control thereof in a manner known per se, each filt~r pack had included therewith a neutral density filter of 1.50 rating, to reduce the intensity of the light from the illuminant source, and also an ultraviolet absorbing filter, utilizing filters for these purposes which are commercially available from Eastman Kodak Company.
The photographic paper was exposed to the illuminant source successively through each filter for each of the in-dicated times for each separation film in succession.
Exposure times were controlled semi-automatically by a DIT
200 (trade mark) timer, marketed by Sergeant-Welch Company.
With the photographic paper thus exposed, it was then,developed in the conventional manner, according to manufacturer's specifications. The exposure and development cycle was completed in about fifteen minutes, and can be even faster if neutral density filters are reduced or not used. Upon , -23-~73L~3~
drying, the developed photographic paper provided an accurate color proof o~ the proposed prin-tiny run based on the color sep~ra-tion negatives at hand, using the selected inks and prin-ted on the type of paper presen-ted.
FIG. 2 diagrammatically shows the overall color printing reproduction procedure utilizing the color proofing technique shown and discussed in connection with FIG. 1. Proceeding from a color original of either a two dimensional or three dimensional nature, four color separation films are prepared in a manner conventional per se, such as by photography. As known, these separation films can be either positives or negatives and of a screened or half or continuous tone character. The color separation films may then either go directly to a printer who does his own color proofing, or to a specialty color proofing shop where the color proof is prepared for subsequent approval and delivery to a printing house. Given a set of color separation films and certain candidate inks and paper or like base on which the color reproduction is to be printed, the printer or color proofer prepares swatches of the inks on the printing base or reasonable facsimile thereof and then proceeds with the production of one or more color proofs, following the procedure illustrated and discussed in connection with FIG. 1. The resulting proof or proofs are then inspected and approved by the printing buyer, such as an advertisiny agency or the like. Prin,ting plates in the respective colors are then prepared from the respective color separation films in a manner conventional per se, such as by known etching processes, and the resulting printing plates are utilized along with the respective selected inks and the selected paper or like printing base during the printing run, also in the manner conventional per se.
8~3 In utilizing this color proofing technique, it will be readily understood that it is applicable to a wide variety of color proofing needs, such as in the reproduction of original works or art or other art work, colored signs, sample variations for textiles, wallpaper variations, .
paint or color swatches, variations in rug pattern colors, plastics, or anything requiring a visual sample or samples of what a finished product might look like in color.
Reproducing colors of natural products such as fruits or vegetables, or a glass of wine, for example, is also an application of the present technique, where the color components of the natural product can be measured with a spectrophotometer and the colors reproduced on photographic paper by the target color reproduction technique of the present invention, then reproduced rom given inks as a printed color reproduction, with the colors of the printed reproduction when printed being "proofed" in relation to selected inks by the color proofing technique of the present invention.
Various modifications, further adaptations and variations will readily occur to those skilled in the arts to which the invention is addressed. Thus, simply by way of further example, it will be recognized that other coloring agents, such as pigments or dyes rather than printer's inks, may be equally well addressed by the target color reproduction technique of the present invention, and that the nature of the base to which the inks or the like (e.g. pigments or dyes) are to be applied may be readily varied. Thus, the particular nature of the printing paper (matte or glossy, for example), ~h ~ 25 ~7~3B
L otiler teXtlll^(.' oE the pr.int base (whicl~ Inay ~e three d:imell-sional sucll as cquipment fronts or calculator keys or the like), can wiclel.y vary in praet:i.ce alld ean }~e readi].y matehed or at least closely simulated in practice of this color proofing technique.
In util:izi.llcJ the present invention, it is an importan-t advantacJe and characterlstie that the determination of the target eolor color consti-tuents ean take into aecount the color of the paper or other printing base itself, which of course contributes its eolors -to the eolors of the ink or the like swatches.
Rather than requiring any partieular co~or proofing Eilms and any partieular type oE film or paper on whieh the eolor proof is to be developed, the color proofing teehnique of the present inven-tion may be used with any photosensitive pho-tographie paper oE any texture, it being reeognized o:E course tha-t un-developed photographic paper is commercially available or ean be made -to order in a wide variety of eolors, -textures and confi.gura-tions and is a eonsiderably more eeonomie eon-sumable than the speeially prepared photopolymerie materials heretofore required for pre-press eo:Lor proofincJ.
Tlle eolor proofing teehnique of the present invention, by means of whieh ~ color proof is ob-tained by suecessive exposure of undeveloped photographic paper to an illuminant light source through color separation films suceessively plaeed in register on the photographie paper and through sueeessive eolor filters for sueeessive exposure times ealculated to substantially reproduee eaeh eolor assoeiated with each color separation film on the photographic paper when developed, is not neeessarily limi-ted to any partieular teehnique for determining the eolor or eolor eomponent makeup of -the ink or -the like with whieh eaeh eolor separation film - ~4~ 38 is correlated. ~l`hus, in a given instance, the correlation between a given ink or the like and a given color separa-tion film, in terms o:E the filters and exposure times necessary to substantially reproduce the ink color on a particular ~5 g.iven photograpllic paper or the li.ke, may be determined as a factory specification or be otherwise available to -the color proofer. 1t is con-templated, Eor e~ample, that a manufacturer and ma-terials supplier to -the color proofing and printing trade can provide the -trade wi-th a color prooEing "package" involvinc3 an inventory of printer's i.nks or the like, an inventory of colored filters and illuminant source or sources, an inventory of types of undeveloped photosensitive photographic paper, and a computer or l:ike equipment pre-programmed to correlate any particular ink and any par-ticular paper with -the available illuminant source~s) and color fil-ters, and provide the appropriate corresponding filter exposure -times, such computing or like equipment as furnished by the manufacturer proviclincJ to tl~e color proo:eer a direct readout o:E the photographic paper -to be used and the illuminant source, filters, and associated exposure times to be used in -the given instance. It is further contempla-ted tha-t, with -these outputs, such an equipment could be automated in the sense that exposure of the paper through each color separa-tion film and its associated group of filters would be auto-matically controlled by the equipment. At the beginningof a run -the color proofer manually inputs to the equipment the identity of the targe-t colors to be reproduced (e.g.
the printer's inks or the like to be used during the prin-ting run), the nature of the paper -to be used during 3~ the printing run, and possibly any corrective inputs ~7~38 des:irc(l .s~lcll al modi.ficati.orls in huc or tonc. 'l'he pre-programmecl equi~ lent would then autornatica:Lly determine the illumi.nant sou~ce, the group oE fil.ters and exposure times to bc usecl to :reprocluce the color oE each given ink or the like, and on demand would automatically sequence the filter exposures through each separation fi].m. Operation of the eqlli.pmellt would involve the color proofer simply sequential.ly regi.stering the first col.or separation Eilm with the photograpllic paper, then activating the equipmen-t to perform the filter exposure sequence associa-ted with the ink correlatecl with tha-t separation film, -then re~oving the first separation film fxom -the paper and registering the second separation film therewith, then again ac-tivating the equipment to perform -the associated filter exposure sequence for the ink correlated with the second Eilm, and so on until the paper is fully exposed through all separation films and associa-ted filters. Following the exposure cycles, then, such equipment could also be automated to automatical.ly develop the photographic paper and deliver -the developed photographic media to the color proofer as the finis}led color proof.
From the foregoing, various further applications, modifications and adaptations of the method disclosed by the foregoing preferred embodiments of the present invention will be apparent to those skilled in the art to which the present invention is addressed, wi-thin the scope of the following claims.
7. NEED . 66 gray level HAVE . 70 " " .66/.70 = .942857 10.1 3.8 2.6 X.942~57 X.942857 X.942857 9.5 3.6 2.4 NEW TIMES for .66 gray 10. Assuming that -these'times for gray are correc-t, the following SATUR~TION TIMES FOR the .66 level of the chromaticity diagram evolve, using the given photo-graphic media used in the example:
9.5/.443458 = 21.4 sec. 3.6/.379670 = 9.4 sec.
2.4/.176872 = 13.56 sec.
Any color can now be exposed for,using these times.
the complement of Thus, for/a dominant wavelength of 410 at the 90% saturation level from the illuminant, can be computed by .083369 .003930 .912701 X21.4 X 9 4 X 13 45 1.8 ~ 04 12.3 As will be evident, the determinations and operations of the exposure equipment can also be accomplished by computer, utilizing programming techniques known per se. In one pro-to-7~
type equipment at hand, an Apple II (trade mark) computer i5 used with a so-called ~, y table to horizontally move -the photo-~raphic media under a stati~nary mask opening through which the media is ill~lminated downwardly from a stationary illuminant source through selected filters. The computer also inter-faces with exposure control mechanism, i.e. the light source and filters. In the phototype arrangement a computer is used with a color TV monitor. All necessary computations to provide the color reference data base for the light source and filters are programmed into the computer in a manner known per se. The photographic media is moved on the x, y table under control of the computer so that the desired exposure point is directly in line with the mask openiny and the light source. Filters are moved into line with the illuminant source sequentially and exposure times are also controlled by the computer to reproduce any desired target color in the manner characteristic of the present invention.
Repeated exposure to develop an array of target colors can result in an entire data base working area being produced~
As earlier indicated, the present invention lnvolves the application of the foregoing target color reproduction method to the field of color printing and specifically to the proofing, prior to the making of printing plates, of the so-called color separation components (film negatives or positives) from which the plates are to be made. Given a set of color separation films and a given set of printer's inks (e.g. yellow, magenta, cyan and black), the present invention provides, through use of photographic printing techniques, a simple and accurate way of determining what 7~
printed color reproductions will look like without actually having to prepare test printing plates. More specifically, the present invention provides a simple and straightforward pre-press color proofing technique whereby a given set of color separation components is "proofed" on photographic paper in a manner showing what the printed color reproduction will be like if printed with a given set of printer's inks, the color proof being "printed" by use of a light source and color filters rather than by use of the inks, with filtered light exposure times coordinated to the ink colors.
In making of color proofs from color separation com-ponents in a manner according to the present invention, each separation component (which is a black film base, positive or negative), may be considered simply as a mask con-trolling the areas or portions of the photographic print paper which are exposed to selected sets of filters for selected times simulating the color composition of the inks. ~y this technique, the "printing" of the photographic paper is ac-complished by light in essentially the same manner as a printer would print with inks, i.e. with all colors "printed" on a single non-transparent sheet of paper, as distinguished from conventional color proofing techniques which commonly involve each primary color and black being developed on separate transparent sheets which are superimposed to simulate'the final printed reproductions.
As a specific example of application of the present invention, it will be understood at the outset tha-t color separation components, as made or available in -the color print-ing field, are derived in a number of ways, such as through a j, ,;
~ 17-camera process, conventional per se, which provides four color separation films, each of which in appearance is a black film base, positive or negative, but which constitutes respective records of the yellow content, -the magenta con-tent, the cyan content, and the black con-tent of the original.
Each such black base film is in effect a mask made of more or less microscopic dots or continuous tone which either parti-ally pass (a negative film) or partially block ~a positive film) light in the course of preparing the corresponding color printing plate to be used in the final printing process.
Each such "dot" or "tone" of the printing plate permits more or less of the corresponding ink to be applied to the paper on which the printed color reproduction is printed.
As diagrammatically illustrated in FIG. 1, to obtain a color proof of what the printed color reproduction will be, using a given set of inks and a given set of color separation components, the printer or color proofer, in utilizing the concepts of the present invention, first makes so-called "draw down" samples of the four inks on the paper or like base which is identical to or at least similar in color and texture to the paper or base on which the printing run is to be made. These are simply samples or "swatches" of the yellow, magenta, cyan and black inks which the printer has tentatively selected for the printing. Each ink s,watch thus produced is then subjected to color analysis, as by comparison with a color reference data base developed and applied as taught by our aforementioned Great Britain Patent No. 1,592,839 to determine in each instance the red, green and blue components thereof, and up to ~hree color filters are selected in each instance from which the color of each ^; -18-ink swatch, as a color proofing target color, can be reproduced from a given light source. As will be understood, with a given light source and with four swatches of a selected set of ink candidates (yellow, magenta, cyan and black), the analysis technique of the present invention provides the color proofer with information as to the identity of each of the up to three color filters to be used in the reproduction of each of the four target colors (the ink swatches), and the light source exposure times to be used with each of the color filters to reproduce each of the four target colors.
With this information at hand, a selected photographic print paper (such as Kodak (trade mark) Ektacolor (-trade mark) RC 74 negative print papex, for example) is placed on pins in the exposure plane associated with the light source and filters (the pins matching pin holes in the separation films). The first (e.g. yellow) separation film is then placed on the un-exposed photographic print paper and the light source and first group of filters (e.g. the yellow group) ar~ controlled to expose the photographic print paper and first (e.g. ~ellow) separation film to the light source in sequence through the associated up to three filters for the determined illumination times to re-produce the first ink target color image on the photographic paper when the paper is developed. The first separatlon film is then removed from the print paper, the second separation film (e.g. magenta) is superimposed on the paper, and the exposure process is repeated using the second group of up to three filters te.g. the magenta group) and the associated exposure times determined for the second (e.g. magenta) ink swatch. The second separation film is then removed from the . ... .
~73~8~
photographic paper and the third (e.g. cyan) separation film superimposed thereon, with the e~posure sequence again repeated using -the up to three color fil-ters of the third group of fil-ters (e.g. the cyan group) and the associated exposure -times determined from the target color analysis of the third (e.g. cyan) ink swatch. The third separation film is -then removed from the photographic paper and the fourth separation film (e.g. black) superimposed thereon, with the exposure sequence again being repeated with the up to three color filters of the fourth group of filters (e.g. the black group~ and the associated exposure times determined for the fourth (e.g. black) ink target color swatch.
The resulting photographic paper, thus exposed, is developed in the conventional manner, and the resulting developed print is an image-wise color proof on a single sheet of opaque paper, accurately showing the color proofer what the finished printed color material will look like when printed on the selected paper by use of the selected inks and printing plates prepared from the selected separation films, it being significant in this respect that the color proof is thus produced without test plates and wi-thout ac-tual use (beyond the preparation of the original ink swatches) of the inks to be used on the paper to be used in the final 25 color printing. `
As a specific example of practice of the present invention, a set of color separation films was prepared from a graphic art overlay of a ci-ty tourist map and related text material. The separa-tion films were produced by compositing various screen effects into four color separation negatives in a known manner. ~pecifically, various color effects were developed on GAF (trade mark) P4 20x24" line negative film, following which the color ef~ects were composited on GAF (trade mark) HD 403 duplicating film ~or the four color separation negative films. Target color samples were obtained from the prin~er on coated web stock white paper (50 lb.) which were draw downs of the four inks to be used in the printing of the maps, namely, Acme Temp (trade mark) Yellow M-76325-A, ~cme Temp (trade mark~ ~roc. Warm Red M-79535, Acme Temp (trade mark) Blue M-76326 and Acme Temp (trade mark) Black M-76990. The available illuminant light source was a GE tungsten map lamp rated at 100 watts at 20 volts, and the temperature thereof was measured to be 3050 Kelvin by a Gossen (trade mark) color temperature meter. The primary color components of the various samples were then measured by a GAM (trade mark) reflection densitometer, Model GAM 126P.
The yellow ink sample was found to have a gray level of 13, a density (proportiona~ percentage) of 23 (13.6%) for blue, 30 (17.8%) for magenta, and 116 (68.6%) for yellow. The magenta or warm red sample was found to have a gray level of 45, a density of 29 (11.3%) for blue, 134 (52.3%) for mayenta, and 93 (36.3%) for yellow. The cyan or blue sample was found to have a gray level of 96, a density of 151 (60.2~) for blue, 64 (25.5~ for magenta, and 36 (14.3%) for yellow. The black ink sample was found to have a gray level of 189, a density of 193 (33.2%) for blue, 193 (33.2%) for magenta, and 196 (33.6%) for yellow.
The x, y and z coordinates of the ink samples were determined by reference to a data base (as in our Great Britain Patent No. 1,592,839), or such can be determined directly by use of a spectrophotometer, as follows:
,,r.~g ~ 21-7~8~3 Ink Sample x y z yellow .4973 .4614 .0275 magenta .6107 .3312 .0579 cya~ .2245 .3193 .4560 black .4597 .4063 .1338 In this example, the filters chosen were the same as employed in the earlier example set forth, namely Kodak (trade mark) Wratten Photomechanical Filters Numbers 25 (red), 58 (green), and ~7B (blue). In this example, the selected undeveloped photographic paper was Kodak (trade mark) Ektacolor ~trade mark) RC 78, type NRC, manufactured by the Eastman Kodak Company. For this paper, the saturation times, adjusted as to each gray level, were determined as earlier set forth, for the red, green and blue filters, to be:
Filter 25 Filter 58Filter 47B
(red) (green) (blue) .. . . __ For gray level:
13 (yellow) 3.5 sec. 8.2 18.3 45 (magenta) 41.8 28.3 63.5 2096 (cyan 89.2 60.4 135.4 189 (black) 175.6 118.9 266.7 From the determined information as to the color component makeup of the samples, the characteristics of the available primary color filters, and the nature and saturation times of the given photographic paper in relation to the ,~ r 22 filters and illuminant source, the corresponding exposure times to substantially reproduce each target color on the photographic paper were determined, with reference to the color reference data base, to be:
Exposure Exposure Exposure Exposure of yellow of magenta of cyan of black separation separation separation separation film film film film Filters 25 (red) 0.2 sec. none 103.7 85.7 58 (green) none 53.0 5.9 52.6 47B ~blue) 36.3 19.0 4.2 46.1 To extend the exposure times for improved control thereof in a manner known per se, each filt~r pack had included therewith a neutral density filter of 1.50 rating, to reduce the intensity of the light from the illuminant source, and also an ultraviolet absorbing filter, utilizing filters for these purposes which are commercially available from Eastman Kodak Company.
The photographic paper was exposed to the illuminant source successively through each filter for each of the in-dicated times for each separation film in succession.
Exposure times were controlled semi-automatically by a DIT
200 (trade mark) timer, marketed by Sergeant-Welch Company.
With the photographic paper thus exposed, it was then,developed in the conventional manner, according to manufacturer's specifications. The exposure and development cycle was completed in about fifteen minutes, and can be even faster if neutral density filters are reduced or not used. Upon , -23-~73L~3~
drying, the developed photographic paper provided an accurate color proof o~ the proposed prin-tiny run based on the color sep~ra-tion negatives at hand, using the selected inks and prin-ted on the type of paper presen-ted.
FIG. 2 diagrammatically shows the overall color printing reproduction procedure utilizing the color proofing technique shown and discussed in connection with FIG. 1. Proceeding from a color original of either a two dimensional or three dimensional nature, four color separation films are prepared in a manner conventional per se, such as by photography. As known, these separation films can be either positives or negatives and of a screened or half or continuous tone character. The color separation films may then either go directly to a printer who does his own color proofing, or to a specialty color proofing shop where the color proof is prepared for subsequent approval and delivery to a printing house. Given a set of color separation films and certain candidate inks and paper or like base on which the color reproduction is to be printed, the printer or color proofer prepares swatches of the inks on the printing base or reasonable facsimile thereof and then proceeds with the production of one or more color proofs, following the procedure illustrated and discussed in connection with FIG. 1. The resulting proof or proofs are then inspected and approved by the printing buyer, such as an advertisiny agency or the like. Prin,ting plates in the respective colors are then prepared from the respective color separation films in a manner conventional per se, such as by known etching processes, and the resulting printing plates are utilized along with the respective selected inks and the selected paper or like printing base during the printing run, also in the manner conventional per se.
8~3 In utilizing this color proofing technique, it will be readily understood that it is applicable to a wide variety of color proofing needs, such as in the reproduction of original works or art or other art work, colored signs, sample variations for textiles, wallpaper variations, .
paint or color swatches, variations in rug pattern colors, plastics, or anything requiring a visual sample or samples of what a finished product might look like in color.
Reproducing colors of natural products such as fruits or vegetables, or a glass of wine, for example, is also an application of the present technique, where the color components of the natural product can be measured with a spectrophotometer and the colors reproduced on photographic paper by the target color reproduction technique of the present invention, then reproduced rom given inks as a printed color reproduction, with the colors of the printed reproduction when printed being "proofed" in relation to selected inks by the color proofing technique of the present invention.
Various modifications, further adaptations and variations will readily occur to those skilled in the arts to which the invention is addressed. Thus, simply by way of further example, it will be recognized that other coloring agents, such as pigments or dyes rather than printer's inks, may be equally well addressed by the target color reproduction technique of the present invention, and that the nature of the base to which the inks or the like (e.g. pigments or dyes) are to be applied may be readily varied. Thus, the particular nature of the printing paper (matte or glossy, for example), ~h ~ 25 ~7~3B
L otiler teXtlll^(.' oE the pr.int base (whicl~ Inay ~e three d:imell-sional sucll as cquipment fronts or calculator keys or the like), can wiclel.y vary in praet:i.ce alld ean }~e readi].y matehed or at least closely simulated in practice of this color proofing technique.
In util:izi.llcJ the present invention, it is an importan-t advantacJe and characterlstie that the determination of the target eolor color consti-tuents ean take into aecount the color of the paper or other printing base itself, which of course contributes its eolors -to the eolors of the ink or the like swatches.
Rather than requiring any partieular co~or proofing Eilms and any partieular type oE film or paper on whieh the eolor proof is to be developed, the color proofing teehnique of the present inven-tion may be used with any photosensitive pho-tographie paper oE any texture, it being reeognized o:E course tha-t un-developed photographic paper is commercially available or ean be made -to order in a wide variety of eolors, -textures and confi.gura-tions and is a eonsiderably more eeonomie eon-sumable than the speeially prepared photopolymerie materials heretofore required for pre-press eo:Lor proofincJ.
Tlle eolor proofing teehnique of the present invention, by means of whieh ~ color proof is ob-tained by suecessive exposure of undeveloped photographic paper to an illuminant light source through color separation films suceessively plaeed in register on the photographie paper and through sueeessive eolor filters for sueeessive exposure times ealculated to substantially reproduee eaeh eolor assoeiated with each color separation film on the photographic paper when developed, is not neeessarily limi-ted to any partieular teehnique for determining the eolor or eolor eomponent makeup of -the ink or -the like with whieh eaeh eolor separation film - ~4~ 38 is correlated. ~l`hus, in a given instance, the correlation between a given ink or the like and a given color separa-tion film, in terms o:E the filters and exposure times necessary to substantially reproduce the ink color on a particular ~5 g.iven photograpllic paper or the li.ke, may be determined as a factory specification or be otherwise available to -the color proofer. 1t is con-templated, Eor e~ample, that a manufacturer and ma-terials supplier to -the color proofing and printing trade can provide the -trade wi-th a color prooEing "package" involvinc3 an inventory of printer's i.nks or the like, an inventory of colored filters and illuminant source or sources, an inventory of types of undeveloped photosensitive photographic paper, and a computer or l:ike equipment pre-programmed to correlate any particular ink and any par-ticular paper with -the available illuminant source~s) and color fil-ters, and provide the appropriate corresponding filter exposure -times, such computing or like equipment as furnished by the manufacturer proviclincJ to tl~e color proo:eer a direct readout o:E the photographic paper -to be used and the illuminant source, filters, and associated exposure times to be used in -the given instance. It is further contempla-ted tha-t, with -these outputs, such an equipment could be automated in the sense that exposure of the paper through each color separa-tion film and its associated group of filters would be auto-matically controlled by the equipment. At the beginningof a run -the color proofer manually inputs to the equipment the identity of the targe-t colors to be reproduced (e.g.
the printer's inks or the like to be used during the prin-ting run), the nature of the paper -to be used during 3~ the printing run, and possibly any corrective inputs ~7~38 des:irc(l .s~lcll al modi.ficati.orls in huc or tonc. 'l'he pre-programmecl equi~ lent would then autornatica:Lly determine the illumi.nant sou~ce, the group oE fil.ters and exposure times to bc usecl to :reprocluce the color oE each given ink or the like, and on demand would automatically sequence the filter exposures through each separation fi].m. Operation of the eqlli.pmellt would involve the color proofer simply sequential.ly regi.stering the first col.or separation Eilm with the photograpllic paper, then activating the equipmen-t to perform the filter exposure sequence associa-ted with the ink correlatecl with tha-t separation film, -then re~oving the first separation film fxom -the paper and registering the second separation film therewith, then again ac-tivating the equipment to perform -the associated filter exposure sequence for the ink correlated with the second Eilm, and so on until the paper is fully exposed through all separation films and associa-ted filters. Following the exposure cycles, then, such equipment could also be automated to automatical.ly develop the photographic paper and deliver -the developed photographic media to the color proofer as the finis}led color proof.
From the foregoing, various further applications, modifications and adaptations of the method disclosed by the foregoing preferred embodiments of the present invention will be apparent to those skilled in the art to which the present invention is addressed, wi-thin the scope of the following claims.
Claims (28)
1. The method of color proofing a set of multi-color separation components, comprising:
(a) successively overlaying an undeveloped color photosensitive surface and exposing the same to an illuminant light source through each color separation component in sequence, with the light source being exposed to the film and photosensitive surface in each instance through successive sets of color filters and for associated successive exposure times substantially reproducing each color image associated with each color separation component on the photosensitive surface when developed, the color reproduced in relation to each color separation component being substantially the color of the ink to be used with a printing plate prepared from such color separation component; and (b) developing the photosensitive surface to provide the color proof.
(a) successively overlaying an undeveloped color photosensitive surface and exposing the same to an illuminant light source through each color separation component in sequence, with the light source being exposed to the film and photosensitive surface in each instance through successive sets of color filters and for associated successive exposure times substantially reproducing each color image associated with each color separation component on the photosensitive surface when developed, the color reproduced in relation to each color separation component being substantially the color of the ink to be used with a printing plate prepared from such color separation component; and (b) developing the photosensitive surface to provide the color proof.
2. The method of claim 1, wherein each color reproduced in relation to each color separation component substantially reproduces the color of the ink to be used with a printing plate prepared from such color separation component.
3. The method of claim 1 or 2, wherein said color photosensitive surface is paper simulating the surface on which printing is to occur using printing plates prepared from the set of color separation components.
4. The method of pre-press color proofing a set of color separation components from which color printing plates are to be made for color printing of a multi-color image on a printing base with a given set of printer's inks, said method comprising:
(a) preparing samples of the given inks on the printing base;
(b) determining the primary color component makeup of each sample in relation to a given illuminant source and, from a color reference data base based on such illuminant source, determining a group of color filters and associated color filter exposure times appropriate to substantially re-produce each sample color on a selected color sensitive photographic paper when the paper is exposed to the illuminant source through such filters for such exposure times;
(c) successively overlaying each color separation component on the undeveloped photographic paper and exposing the undeveloped photographic paper to the light source in sequence through each color separation component and its as-sociated group of color filters for the determined respective filter exposure times to substantially reproduce each separation color image in the associated sample color on the photographic paper when developed, and (d) developing the exposed photographic paper to provide a pre-press color proof.
(a) preparing samples of the given inks on the printing base;
(b) determining the primary color component makeup of each sample in relation to a given illuminant source and, from a color reference data base based on such illuminant source, determining a group of color filters and associated color filter exposure times appropriate to substantially re-produce each sample color on a selected color sensitive photographic paper when the paper is exposed to the illuminant source through such filters for such exposure times;
(c) successively overlaying each color separation component on the undeveloped photographic paper and exposing the undeveloped photographic paper to the light source in sequence through each color separation component and its as-sociated group of color filters for the determined respective filter exposure times to substantially reproduce each separation color image in the associated sample color on the photographic paper when developed, and (d) developing the exposed photographic paper to provide a pre-press color proof.
5. The method of claim 4, wherein the color component makeup of each sample is determined spectrophotometrically.
6. The method of claim 4, as applied to color proofing a set of color separation components based on colored pictorial material.
7. The method of claim 4, as applied to color proofing a set of color separation components based on graphic art work.
8. The method of claim 4, as applied to color proofing a set of color separation components based on a three-dimensional object.
9. The method of claim 4, as applied to color proofing a set of color separation components based on a color dyed textile or fabric.
10. The method of claim 4, as applied to color proofing a set of color separation components based on pigmented paint.
11. The method of claim 4, as applied to color proofing a set of color separation components based on color dyed carpet or rug material.
12. A method of pre-press color proofing a set of color separation components from which printing plates are to be made for color printing of a multi-color image on a printing base with a given set of printer's inks, said method comprising:
(a) preparing samples of the given inks on the printing base;
(b) illuminating the prepared samples with a given light source and determining the proportion of three primary colors of red, green and blue which constitute each sample color by comparing each said sample color to a data base comprising a plurality of colors constituted of said primary colors under illumination by a like light source whereby to select from said data base reference colors most similar to the sample colors and thereby identify groups of one or more color filter elements usable to reproduce each such reference color;
(c) determining the exposure times for each color filter element of each group of color filters required sub-stantially to reproduce the color of each sample color on color sensitive photographic material when developed;
(d) exposing undeveloped color sensitive photographic material through each color filter element of each group and through each respective color separation component for a period corresponding to the exposure time thus determined;
and (e) developing the exposed color sensitive photo-graphic material thereby substantially to reproduce the multi-color image thereon.
(a) preparing samples of the given inks on the printing base;
(b) illuminating the prepared samples with a given light source and determining the proportion of three primary colors of red, green and blue which constitute each sample color by comparing each said sample color to a data base comprising a plurality of colors constituted of said primary colors under illumination by a like light source whereby to select from said data base reference colors most similar to the sample colors and thereby identify groups of one or more color filter elements usable to reproduce each such reference color;
(c) determining the exposure times for each color filter element of each group of color filters required sub-stantially to reproduce the color of each sample color on color sensitive photographic material when developed;
(d) exposing undeveloped color sensitive photographic material through each color filter element of each group and through each respective color separation component for a period corresponding to the exposure time thus determined;
and (e) developing the exposed color sensitive photo-graphic material thereby substantially to reproduce the multi-color image thereon.
13. The method of color proofing of claim 12, as applied to the preparation of a color proof from a set of four color separation components.
;,
;,
14. A method for pre-press color proofing of a colored image using color photographic material, a liyht source, a set of color filter elements, and a set of color separation films, said method comprising:
(a) illuminating at least one sample of a selected printing ink with a light source and determining the proportion of three primary colors of red, green and blue which constitute said printing ink by comparing each said sample to a data base comprising a plurality of colors constituted of said primary colors obtained by illuminating said primary colors with a light source whereby to select from said data base a reference color most similar to the sample color and thereby identify a group of one or more color filter elements used to prepare said reference color;
(b) determining the exposure time of each color filter element required substantially to reproduce the sample color on said color photographic material when developed;
(c) exposing undeveloped color photographic mater.ial through the color filter elements and each respective color separation film of said set of color separation films using said illuminant source for a period corresponding to the exposure time determined for each respective color filter element and color separation film; and (d) developing the exposed color photographic material thereby substantially to reproduce the colored image thereon.
(a) illuminating at least one sample of a selected printing ink with a light source and determining the proportion of three primary colors of red, green and blue which constitute said printing ink by comparing each said sample to a data base comprising a plurality of colors constituted of said primary colors obtained by illuminating said primary colors with a light source whereby to select from said data base a reference color most similar to the sample color and thereby identify a group of one or more color filter elements used to prepare said reference color;
(b) determining the exposure time of each color filter element required substantially to reproduce the sample color on said color photographic material when developed;
(c) exposing undeveloped color photographic mater.ial through the color filter elements and each respective color separation film of said set of color separation films using said illuminant source for a period corresponding to the exposure time determined for each respective color filter element and color separation film; and (d) developing the exposed color photographic material thereby substantially to reproduce the colored image thereon.
15. The method of claim 14, wherein said undeveloped color photographic material is exposed to said illuminant source in sequence through at least one color separation film.
=33-
=33-
16. The method of claim 14, wherein the color component makeup of each selected printing ink is determined spectrophotometrically.
17. The method of obtaining a target color on color photosensitive photographic media, utilizing an illuminant source and color filters, said method comprising:
(a) preparing a color reference data base relating a given illuminant source at a given Kelvin temperature and a given spectral distribution with various color filters and various undeveloped color photosensitive photographic media, and providing information as to which filters and respective filter exposure times are appropriate, when used with such an illuminant source and given photographic media, to substan-tially reproduce a given target color on the developed photo-graphic media, (b) determining the constituent primary color component makeup of the target color in relation to the illuminant source, (c) from the target color component makeup, determining from the data base a group of color filters and the associated color filter exposure times appropriate to substantially reproduce the target color on a given photographic media when developed, (d) exposing the undeveloped color sensitive photo-graphic media to the illuminant source through each color filter for each respective filter exposure time thus determined, to substantially reproduce the target color on the photographic media when developed, and (e) developing the exposed photographic media.
(a) preparing a color reference data base relating a given illuminant source at a given Kelvin temperature and a given spectral distribution with various color filters and various undeveloped color photosensitive photographic media, and providing information as to which filters and respective filter exposure times are appropriate, when used with such an illuminant source and given photographic media, to substan-tially reproduce a given target color on the developed photo-graphic media, (b) determining the constituent primary color component makeup of the target color in relation to the illuminant source, (c) from the target color component makeup, determining from the data base a group of color filters and the associated color filter exposure times appropriate to substantially reproduce the target color on a given photographic media when developed, (d) exposing the undeveloped color sensitive photo-graphic media to the illuminant source through each color filter for each respective filter exposure time thus determined, to substantially reproduce the target color on the photographic media when developed, and (e) developing the exposed photographic media.
18. The method of claim 17, comprising determining the target color color constituency by means of a densitometer.
19. The method of claim 17, comprising determining the target color color constituency by means of a spectrophoto-meter.
20. The method of claim 18 or 19, further comprising the step of proportionately varying the length of the exposure times for all of the color filters to thereby produce tints or tones of the target color.
21. The method of claim 17, as applied to the preparation of a color proof from a set of color separation components, comprising:
(a) preparing target color samples in the form of swatches made from respective primary color and black printer's inks and determining the color component makeup of each in relation to the illuminant source;
(b) determining from the color component makeup of the inks and from the color reference data base, the respective color filters and respective exposure times appropriate to substantially reproduce each target color on the photographic media when developed;
(c) successively overlaying each color separation component on the undeveloped photographic media and exposing the photographic media to the illuminant source through each color separation component and its associated group of color filters for the determined respective exposure times to sub-stantially reproduce each separation film color image in the associated target color on the photographic media when developed; and (d) developing the exposed photographic media to provide the color proof.
(a) preparing target color samples in the form of swatches made from respective primary color and black printer's inks and determining the color component makeup of each in relation to the illuminant source;
(b) determining from the color component makeup of the inks and from the color reference data base, the respective color filters and respective exposure times appropriate to substantially reproduce each target color on the photographic media when developed;
(c) successively overlaying each color separation component on the undeveloped photographic media and exposing the photographic media to the illuminant source through each color separation component and its associated group of color filters for the determined respective exposure times to sub-stantially reproduce each separation film color image in the associated target color on the photographic media when developed; and (d) developing the exposed photographic media to provide the color proof.
22. A method of obtaining a target color on color photosensitive photographic media, utilizing a given light source and color filters, said method comprising:
(a) preparing a color reference data base expressing the primary color component makeup of a plurality of colors illuminated by the light source, (b) determining from the data base the constituent primary color component makeup of the target color under illumination by a like light source, (c) selecting a group of filters capable of reproducing the target color by appropriate sequential exposures and development of the color sensitive photographic material, (d) determining from the constituent primary color component makeup of each filter under illumination by a like light source and from the color component makeup and saturation time of the photographic material in relation to the given light source the respective color filter exposure times ap-propriate to substantially reproduce the target color on the photographic media when developed, (e) exposing the undeveloped color sensitive photo-graphic media to the light source in sequence through each color filter for each respective filter exposure time thus determined, to substantially reproduce the target color on the photographic media when developed; and (f) developing the exposed photographic media.
(a) preparing a color reference data base expressing the primary color component makeup of a plurality of colors illuminated by the light source, (b) determining from the data base the constituent primary color component makeup of the target color under illumination by a like light source, (c) selecting a group of filters capable of reproducing the target color by appropriate sequential exposures and development of the color sensitive photographic material, (d) determining from the constituent primary color component makeup of each filter under illumination by a like light source and from the color component makeup and saturation time of the photographic material in relation to the given light source the respective color filter exposure times ap-propriate to substantially reproduce the target color on the photographic media when developed, (e) exposing the undeveloped color sensitive photo-graphic media to the light source in sequence through each color filter for each respective filter exposure time thus determined, to substantially reproduce the target color on the photographic media when developed; and (f) developing the exposed photographic media.
23. A method of photographically substantially re-producing a target color on color sensitive photographic material using a light source and a group of one or more color filter elements, said method comprising:
(a) illuminating the target color with the light source or equivalent thereof and determining the proportion of the three primary colors which constitute said target color by comparing the target color to a color reference data base comprising a plurality of colors constituted of said primary colors under illumination by a like light source whereby to select from said data base a reference color most similar to the target color and thereby identify a group of one or more color filter elements usable to reproduce the reference color;
(b) determining the exposure time of each color filter element required substantially to reproduce the reference color and thus the target color on the color sensitive photographic material when developed;
(c) exposing undeveloped color sensitive photographic material through each color filter element for a period corresponding to the exposure time thus determined for each respective color filter element; and (d) developing the exposed color sensitive photographic material thereby substantially to reproduce the target color thereon.
(a) illuminating the target color with the light source or equivalent thereof and determining the proportion of the three primary colors which constitute said target color by comparing the target color to a color reference data base comprising a plurality of colors constituted of said primary colors under illumination by a like light source whereby to select from said data base a reference color most similar to the target color and thereby identify a group of one or more color filter elements usable to reproduce the reference color;
(b) determining the exposure time of each color filter element required substantially to reproduce the reference color and thus the target color on the color sensitive photographic material when developed;
(c) exposing undeveloped color sensitive photographic material through each color filter element for a period corresponding to the exposure time thus determined for each respective color filter element; and (d) developing the exposed color sensitive photographic material thereby substantially to reproduce the target color thereon.
24. The method of claim 23, wherein the color component makeup of the target color is determined by means of a spectrophotometer.
25. The method of claim 23, wherein the color component densities and gray level of the target color are determined by means of a densitometer.
26. A method of photographically substantially re-producing a target color directly on color sensitive photo-graphic material using a given light source and a group of one or more color filters, said method comprising:
(a) identifying the proportionate primary color component density and gray level of the target color in relation to the given light source at a given Kelvin tempera-ture and with a given spectral distribution;
(b) selecting a given color sensitive photographic material and identifying the primary color component makeup and saturation time thereof in relation to such given light source;
(c) inputting such target color and photographic media characteristics to a color reference data base corre-lating such characteristics with the color component makeups and filter percentages of various color filters determined in relation to the given light source and determining from such color reference data base the identity of and respective exposure times necessary substantially to reproduce the target color on the color sensitive photographic material by exposure thereof to the illuminant source through the group of color filters;
(d) exposing the given color sensitive photographic material to the given light source through each of the group of such color filters for each respective exposure time thus determined; and (e) developing the exposed color sensitive photo-graphic material to substantially reproduce the target color thereon.
(a) identifying the proportionate primary color component density and gray level of the target color in relation to the given light source at a given Kelvin tempera-ture and with a given spectral distribution;
(b) selecting a given color sensitive photographic material and identifying the primary color component makeup and saturation time thereof in relation to such given light source;
(c) inputting such target color and photographic media characteristics to a color reference data base corre-lating such characteristics with the color component makeups and filter percentages of various color filters determined in relation to the given light source and determining from such color reference data base the identity of and respective exposure times necessary substantially to reproduce the target color on the color sensitive photographic material by exposure thereof to the illuminant source through the group of color filters;
(d) exposing the given color sensitive photographic material to the given light source through each of the group of such color filters for each respective exposure time thus determined; and (e) developing the exposed color sensitive photo-graphic material to substantially reproduce the target color thereon.
27. The method of claim 26, comprising determining the target color color constituency by means of a densitometer.
28. The method of claim 26, comprising determining the target color color constituency by means of a spectrophotometer.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US770279A | 1979-01-30 | 1979-01-30 | |
| US007,702 | 1979-01-30 | ||
| US7649979A | 1979-09-17 | 1979-09-17 | |
| US076,499 | 1979-09-17 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1147188A true CA1147188A (en) | 1983-05-31 |
Family
ID=26677290
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000344241A Expired CA1147188A (en) | 1979-01-30 | 1980-01-23 | Pre-press color proofing by light exposure to photographic media |
Country Status (4)
| Country | Link |
|---|---|
| CA (1) | CA1147188A (en) |
| CH (1) | CH655394B (en) |
| DE (1) | DE3003318A1 (en) |
| GB (1) | GB2043950B (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0134396A1 (en) * | 1983-08-17 | 1985-03-20 | Kabushiki Kaisha Ueshina Bunmeido | Method and apparatus for proofing multicolor prints |
| FR2590691B1 (en) * | 1985-11-25 | 1988-01-22 | Elf Aquitaine | SEMI-AUTOMATED INSOLATION DEVICE FOR POLYCHROMY. |
| US5019484A (en) * | 1987-12-18 | 1991-05-28 | Konica Corporation | Method and apparatus for forming color proof |
| USD969087S1 (en) * | 2021-01-05 | 2022-11-08 | Dongguan Zhenghao Electrical Co., Ltd. | Power strip |
| USD961522S1 (en) * | 2021-02-03 | 2022-08-23 | Huimin Li | Power strip |
| USD963584S1 (en) * | 2021-03-29 | 2022-09-13 | Guangdong Ldnio Electronic Technology Co., Ltd. | Power distributor |
| USD963585S1 (en) * | 2021-04-08 | 2022-09-13 | Guange (Shenzhen) Electric Co., Ltd. | Power strip |
| USD973597S1 (en) * | 2021-04-26 | 2022-12-27 | Houwei Hong | Socket |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH545491A (en) * | 1970-07-24 | 1973-12-15 | Kirsch Hans Rudolph | Process for the production of a screened, photographic color copy simulating a multicolor print |
| CH544954A (en) * | 1970-07-24 | 1973-11-30 | Ciba Geigy Ag | Process for the production of a screened photographic color copy simulating a multicolor print |
-
1980
- 1980-01-23 CA CA000344241A patent/CA1147188A/en not_active Expired
- 1980-01-28 CH CH64680A patent/CH655394B/de unknown
- 1980-01-30 GB GB8003061A patent/GB2043950B/en not_active Expired
- 1980-01-30 DE DE19803003318 patent/DE3003318A1/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| CH655394B (en) | 1986-04-15 |
| DE3003318A1 (en) | 1980-08-07 |
| GB2043950B (en) | 1983-05-11 |
| GB2043950A (en) | 1980-10-08 |
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