US3839036A - Process for the production of copies of a standardized density - Google Patents

Process for the production of copies of a standardized density Download PDF

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Publication number
US3839036A
US3839036A US00221675A US22167572A US3839036A US 3839036 A US3839036 A US 3839036A US 00221675 A US00221675 A US 00221675A US 22167572 A US22167572 A US 22167572A US 3839036 A US3839036 A US 3839036A
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emulsion
light
density
range
negative
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US00221675A
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E Hellmig
J Vanheerentals
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Agfa Gevaert AG
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Agfa Gevaert AG
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
    • G03C1/46—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein having more than one photosensitive layer
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
    • G03C1/485—Direct positive emulsions

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  • ABSTRACT Positive photographic images of substantially the same high density and substantially the same low density are produced from negatives having wide range of densities but substantially the same shadow density by printing the negatives on printing material that prints with different contrast when exposed to different colors, but produces substantially the same high density for the same exposure times, and adjusting the exposure proportion to both colors to bring the low density to substantially the same low level.
  • the present invention relates to a process for the production of photographic copies of substantially uniform minimum and maximum densities.
  • Photographic prints which are to be used for producing copies by ink duplicating such as through the use of a photoresist layer or on so-called pigment paper or on carbon tissue, irrespective of whether the inked duplications are continuous tone images or screen images, must meet certain conditions as regards the minimum or maximum densities, i.e., the densities for thelight and shadow portions, in order to produce the best results.
  • the original continuous-tone positive photographic prints used for producing copies on pigment paper should have a minimum density of 0.3 0.05 for black-white copies and a density range i.e., the difference in the densities for the light and shadow portions, of 1.35 i 0.05 (DIN 16,602). Similar requirements are applicable to the making of color separation prints and can also be applied to the making of color separation negatives.
  • black-white continuous tone reflection originals will normally have densities which range between about 0.7 and 2.0.
  • Transparent originals e.g. color diapositives (transparencies) from which negative color separation records are to be produced, have even widerdensity ranges (about 0.7 to 3.0).
  • light and shadow densities are meant the maximum and minimum densities in the negatives, and the minimum and maximumdensities in the positives. Adjusting for these differences hinders efforts to make photographic processes efficient and economical.
  • FIG. 1 shows a set of characteristic curves of a photographic material containing two silver halide emulsions being differently sensitized upon exposure to light of different colors according to the process of the present invention
  • FIG. 2 is a similar graphical representation in connection with a modification of the present invention
  • FIG. 3 shows the spectral density curves of the filters that can be used in connection with the present invention.
  • a process for the production of positive photographic continuous-tone images having substantially equal low density in the highlights and substantially equal high density in the shadow portions from black-white negative continuous-tone originals of different density range but substantially equal density of the shadow portions which process comprises providing a printing material having two silver halide emulsions of different spectral sensitivities and contrasts, adjusting the sensitivity of the emulsions or the intensity of the copying light to obtain characteristic curves which intersect at the high density value within the range of from 1.5 to 2.0 when given same exposures to lights to which the emulsions are preferably sensitive, printing on said printing material a positive copy of said negative original using substantially the same total exposure time sum of both exposure-times for each negative selecting the proportion of the printing lights to which the printing material is sensitive by only measuring the maximum density of that negative original, so as to provide a contrast range of the positive copy that brings the highlight density to substantially the same low level.
  • the process of the present invention results in positive copies which have approximately equal maximum and minimum densities from negative originals which have substantially equal density of the shadow portions (low density areas) but which differ greatly in their density range-in other words in their maximum density by using a printing material having at least two silver halide emulsions of different spectral sensitivities, the 'y-value of the silver halide emulsions varying with the color of the copying light so that a sufficiently flat -y-value is obtained with a light color L, and a sufficiently steep y-value is obtained with another light color L the sensitivities of the silver halide emulsions and/or the intensity of the copying lights L, and/or L used for the exposure being so adjusted to each other that when using the same exposure time for light of the color L, and light of the color L and/or for exposures partly with L, and partly with L the characteristic curves obtained intersect at the level of the desired density value D for the shadow portions in the positive copy. That density value generally is within the range
  • step 2 exposing the printing material through the negative original with the printing light.
  • step 2 wherein substantially the same total exposure time is applied for each negative and further processing the thus exposed printing material by development and fixing according to common practice.
  • the crux of this process is the adjustment of the silver halide emulsions of the printing material and/or the intensity of the printing light as explained above in step 1 of the process.
  • the desired adjustment of the two characteristic curves produced with light of the color L, or L is obtained with a given photographic material of the above described composition by altering the characteristic curve of that emulsion which is too sensitive into the desired less sensitive position on the log i.t axis by reducing the radiation of the particular color until the point of intersection of the two curves lies at the re quired density value.
  • the characteristic curves which are obtained when exposure is carried out for the same total length of time but partly with light of color L, and partly with light of color L either simultaneously or successively, should pass through the same desired density value.
  • the characteristic curves 1 to 6 represent exposure to the two light colors (L, and L according to the following proportions, given as percentage values:
  • Run of the mill negatives used in the printing industry generally have a minimum (shadow) density of fairly close to 0.3, so that a present constant exposure effectiveness along any of the curves of FIG. 11 will provide a positive image in which the actual maximum point density of each print is at the level of P.
  • a departure of 0.1 or 0.2 density units from the minimum expected negative density of 0.3 is not frequent and will not make any material difference in the maximum print density.
  • the minimum density of each positive can be arranged to fall at the desired density level, preferably 0.3.
  • the selection is readily effected by merely measuring the maximum density of each negative with any densitometer.
  • the two different colors used in the exposure step of the present invention can be taken from any portions of the light spectrum, both visible as well as ultraviolet and infra-red.
  • the visible colors such as red, green and blue or even yellow are preferred in as much as misoperation of the exposure light is then more readily detected.
  • These colors can be generated by separate light sources, or a single light source can be used with an appropriate filter arrangement either fixed in place or shifted in and out of the light path to make the separate colors. Such light sources are also shown in US. Pat. No. 3,531,199.
  • the exposures to the two colors can be made simultaneous or successive, or partially simultaneous and partially simultaneous and partially successive.
  • FIG. 2 illustrates a special case where characteristic curves for partial exposures do not have exactly the same shadow density as they do for 100 percent exposure with light color L or L but are different by a value indicated by the space between the vertical dashed lines when exposure is carried out with percent L and 40 percent L (curve 3). This difference can be allowed for by a suitable slight shortening or lengthening of the total exposure time when making such partial exposure. If there is, for example, a deviation of about 0.1 log I.t units towards a higher sensitivity (as shown) the proportional exposure times for curve 3 should be shortened to 0.8 times the proportional amounts (log 0.8 0.1).
  • the shadow portions of the original negatives which are to be copied show differences in density, these may also be eliminated by a suitable correction to the total exposure.
  • the two characteristic curves for L l and v L can also'be adjusted during production of the photographic film by suitable spectral sensitization of the two silver halide emulsions so that t is not necessary to use any means for reducing the light, or such use can be limited to a minimum amount of fine adjustment, in contrast to coarse adjustment which is made to the film during production.
  • the copying material can then be out the process according to the invention.
  • Such a material, including its method of production, has been described e.g. in U.S. Pat. No. 2,280,300, British Pat. No.
  • German Patent Application A 56 772 IX- a/Sflb published as Offenlegungsschrift 1,597,476).
  • the material according to the British Patent consists, for example, of a mixture of two silver halide emulsions of different gamma which have been produced independently of each other, one of which is asilver chloride emulsion and the othera silver bromide or silver chlorobromide emulsion, the silver chloride emulsion being sensitized to light from the visible spectrum to which the other emulsion is insensitive or less sensitive.
  • the light-sensitive materials disclosed in the other patent and patent application are of similar composition.
  • the advantages of the process according to the invention are particularly valuable if an automatic exposure process is used. Since the range of exposuretimes is greatly restricted in the process according to the invention, from 32 to 3.2 according to the figures given below, in other words to one-tenth of the times required in the earlier method of procedure, a more uniform production is possible. The range of exposure times can be kept short in the process according to the invention, and because of such smaller range, the automatic exposure instruments can be simpler in construction, with the result that they are less liable to break down and cheaper to manufacture.
  • the present invention can also be carried out with a single silver halide emulsion to provide the varying contrast.
  • a copying material having a silver halide emulsion layer with steep gamma-value greater than 4.0 in combination with a colored contact screen provides positive half tone copies whose contrast varies with the color of the copying light in such a manner that a first gamma-value is obtained with a light of color L, and a steeper gamma-value with another light of color L
  • the spectral sensitivity of the said silver halide emulsion layer and/or the relative intensity of the copying lights L, and L used for exposure are adjusted so that for a given exposure time to light of color L or to light of color L and/or partial exposure to L, to L the resulting characteristic curves intersect'at the particular valueto be obtained in the shadow tive copy.
  • a magenta-colored contact screen is preferred. Phoportions of the positographic materials. with a very steep gamma value are known under the name lithfilm.
  • the variation of the gamma-value of the half-tone positive is based on the fact that the properties of the colored contact screen depend on the color of light used.
  • the density range which can be covered by the combination of the high contrast emulsion with the colored screen can be adapted to that of the continuous-tone negative original by varying the color of the light source. This is not the case with a normal grey screen.
  • the density range which a grey contact screen can cover is calculated by subtracting the minimum density between two screen dots from the maximum density of one screen dot.
  • the density range a certain type of neutral grey screen is able to reproduce is from 0.2 to 1.6 or a spread of 1.4. This is the density range which the continuous-tone negative mustpossess to produce a screen positive. with a. minimum dot size of 0 per cent and a maximum dot size of 100 per cent.
  • magenta contact screen can cover.
  • the density range which the magenta screen is able to cover will also be depend on the color of the lightsource. For example one magenta screen when used with a green light shows a density range from 0.4 to 2.1 for a spread of 1.7.
  • the density range which can be covered when using blue light is 0.2 to 1.2, or 1.0..
  • Example 1 An orthochromatic silver chlorobromide gelatin emulsion with a relatively steep gamma-value is applied to one surface of a transparent support of polyethylene terephthalate (thickness 180p). The other side of the support is coated with a non-sensitized, silver iodobromide gelatin emulsion having a relatively flat gamma. A combination of this type is illustrated in FIG. 4 of British Patent No. 494,088.
  • the adjustment of the material to the conditions of exposure in accordance with the invention is performed as follows:
  • the photographic material described above is exposed to light of color L in a conventional copying apparatus behind a grey wedge through a blue filter which transmits light of a wavelength between 400 and 500 millimicrons, e.g. the blue separation filter B 479 of Agfa-Gevaert AG.
  • Another strip of the material is exposed to light of color L in the same apparatus for the same exposure time through a yellow filter which transmits light of a wavelength down to about 500 millimicrons, e.g. the yellow filter R 519 of Agfa-Gevaert AG. Both strips are developed and processed identically.
  • the copying light for that curve which is too sensitive gives a too high density is combined with a grey filter which has a density value that can be calculated from the characteristic curves by the horizontal distance between the two curves at the density 1.7.
  • Example 11 A neutral silver chloride-bromide emulsion prepared by simultaneous addition from separate jets of a silver nitrate solution and a solution of the water-soluble halide mole percent bromide and 15 mole percent chloride containing traces of iodide 0.15 mole percent, average grain size 0.25 micron) into a gelatin solution (emulsion B), was after optimal chemical ripening mixed with a highly sensitive ammoniacal silver bromide-iodide emulsion (emulsion A, having an average grain size 0.8 micron) containing 6.5 mole percent of iodide prepared by a slow addition of ammoniacal silver nitrate in an aqueous solution containing an excess of dissolved halide.
  • emulsion A having an average grain size 0.8 micron
  • the sensitivity of the emulsion A in the inherent sensitivity region was found to be about 10 times the inherent sensitivity of emulsion B.
  • the emulsions A and B were mixed in a molar ratio of 2,6621.
  • the emulsion mixture was spectrally sensitized with 20 mg of the sensitizing dye H C2OOC I (simmer per 0.34 mole of silver halide and was coated at a rate of 0.059 mole of silver halide per square meter after incorporation of the necessary emulsion ingredients such as stabilizing, hardening and wetting agents. Two strips of the light-sensitive material were respectively exposed through the filters U 449 and L 519 the densityversus-wavelength curves of which are given in FIG. 3.
  • Example IV The same emulsion combination and coating conditions were applied as described in Example 11 except that one emulsion portion K was sensitized with 13 mg of the mentioned sensitizing agent and another emulsion portion L having the same silver halide content sensitized with 26 mg of the same sensitizing agent.
  • Example V A highly sensitive silver bromideiodide emulsion containing 6 mole percent of iodide prepared by a separate addition of a silver nitrate solution aand potassium iodide in an excess of bromide was mixed in a molar ratio of 3 to 1 with a silver chloride bromide emulsion of the acid type containing 70 mole percent of bromide and 30 mole percent of chloride.
  • Example VI A bromide-iodide emulsion prepared as described in Example V was mixed in a ratio of 3 to 1 with a silver chloride bromide emulsion prepared by double jet precipitation containing mole percent of chloride and 40 mole percent of bromide.
  • the emulsion mixture was spectrally sensitized with 12 mg ot the sensitizing dye of Example V per 0.24 mole of silver halide and coated at a rate of 0.047 mole of silver halide per square meter.
  • one silver halide emulsion is an orthochromatically sensitizing silver halide gelatin emulsion and the second is a blue sensitive silver halide emulsion and wherein the light comprises light from the green and blue range of the visible spectrum.

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  • Chemical Kinetics & Catalysis (AREA)
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US00221675A 1968-01-20 1972-01-28 Process for the production of copies of a standardized density Expired - Lifetime US3839036A (en)

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DE1622255A DE1622255C3 (de) 1968-01-20 1968-01-20 Verfahren zur Herstellung dichtemäßig standardisierter Kopien

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US (1) US3839036A (pl)
BE (1) BE727089A (pl)
DE (1) DE1622255C3 (pl)
FR (1) FR2000497A1 (pl)
GB (1) GB1262304A (pl)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4230795A (en) * 1979-04-26 1980-10-28 Donald Krause Multipart photosensitive element with both fixed contrast and variable contrast part records

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB494088A (en) * 1937-03-18 1938-10-18 Frank Forster Renwick Improvements in or relating to photographic printing processes and materials
US3141773A (en) * 1957-02-12 1964-07-21 Agfa Ag Process and photographic material for the production of photographic records and copies which are corrected for tone value
US3450536A (en) * 1961-03-24 1969-06-17 Eg & G Inc Silver halide photographic film having increased exposure-response characteristics
US3628960A (en) * 1967-04-21 1971-12-21 Agfa Gevaert Nv Light sensitive halide material with variable contrast
US3753707A (en) * 1967-04-26 1973-08-21 Agfa Gevaert Ag Method of controlling exposure during photographic printing of variable contrast material

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2202026A (en) * 1937-03-18 1940-05-28 Ilford Ltd Photographic printing process and material
US2280300A (en) * 1941-01-14 1942-04-21 Defender Photo Supply Co Inc Light sensitive photographic coating and method of manufacturing the same

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB494088A (en) * 1937-03-18 1938-10-18 Frank Forster Renwick Improvements in or relating to photographic printing processes and materials
US3141773A (en) * 1957-02-12 1964-07-21 Agfa Ag Process and photographic material for the production of photographic records and copies which are corrected for tone value
US3450536A (en) * 1961-03-24 1969-06-17 Eg & G Inc Silver halide photographic film having increased exposure-response characteristics
US3628960A (en) * 1967-04-21 1971-12-21 Agfa Gevaert Nv Light sensitive halide material with variable contrast
US3753707A (en) * 1967-04-26 1973-08-21 Agfa Gevaert Ag Method of controlling exposure during photographic printing of variable contrast material

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4230795A (en) * 1979-04-26 1980-10-28 Donald Krause Multipart photosensitive element with both fixed contrast and variable contrast part records

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FR2000497A1 (pl) 1969-09-05
BE727089A (pl) 1969-07-22
DE1622255B2 (de) 1981-01-08
GB1262304A (en) 1972-02-02
DE1622255C3 (de) 1981-11-05
DE1622255A1 (de) 1970-12-23

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