US3779755A - Photographic process - Google Patents

Photographic process Download PDF

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Publication number
US3779755A
US3779755A US00162415A US3779755DA US3779755A US 3779755 A US3779755 A US 3779755A US 00162415 A US00162415 A US 00162415A US 3779755D A US3779755D A US 3779755DA US 3779755 A US3779755 A US 3779755A
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United States
Prior art keywords
density
screen
photographic
brightness
photographic material
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Expired - Lifetime
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US00162415A
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English (en)
Inventor
H Schellenberger
Rintelen H Von
E Ranz
H Schutz
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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
    • G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
    • G03C5/02—Sensitometric processes, e.g. determining sensitivity, colour sensitivity, gradation, graininess, density; Making sensitometric wedges
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J1/00—Photometry, e.g. photographic exposure meter
    • G01J1/10—Photometry, e.g. photographic exposure meter by comparison with reference light or electric value provisionally void
    • G01J1/12—Photometry, e.g. photographic exposure meter by comparison with reference light or electric value provisionally void using wholly visual means
    • G01J1/14—Photometry, e.g. photographic exposure meter by comparison with reference light or electric value provisionally void using wholly visual means using comparison with a surface of graded brightness
    • 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
    • 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
    • G03C1/035—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein characterised by the crystal form or composition, e.g. mixed grain
    • 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
    • G03F5/00—Screening processes; Screens therefor
    • 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
    • G03C1/035—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein characterised by the crystal form or composition, e.g. mixed grain
    • G03C2001/03564—Mixed grains or mixture of emulsions

Definitions

  • ABSTRACT The brightness and density distribution of an object can be digitally measured photographically by exposing a light-sensitive photographic material at a dot screen or the like and to the object to be measured, and photographically processing the exposed lightsensitive material to produce equidensity images in which different densities of the object are differently represented.
  • PHOTOGRAPI-IIC PROCESS The invention relates to a photographic process for the digital measurement of brightness or density distributions.
  • Purely physical photometric methods for the determination of brightness or density distributions of photographic original copies can be used e.g., by means of point by point measurement with photoelectric cells or photometers. However, it is also possible to determine lines or areas of equal density (equidensities) or brightness by photographic processes.
  • the simplest photographic process for the production of equidensities is one in which a transparent positive is first produced from a negative. The two are then brought in register with each other either exactly or with a slight shift. A copy of this combination of negative and positive then provides a type of equidensity.
  • an original copy together with a raster is recopied onto a normal photographic material so that a screened copy is obtained.
  • this half-tone copy is viewed by dark field illumination, the screen points are altered in such a way that characteristic symbols are obtained for certain relatively narrow ranges of brightness and density.
  • the entire density distribution of an original image is therefore recorded on a copy and becomes measurable.
  • This method has the disadvantage of requiring a device for dark field illumination. Moreover, it is necessary to produce a copy of this dark field image for the purpose of evaluating the results and as a record.
  • the objects whose brightness or density distribution are to be measured are mainly photographic originals.
  • the processaccording to the invention also enables the brightness distribution of sources of light to be measured directly by means of a photographic camera, e.g., in the case of illumination measurement.
  • FIGS. 1 4 Various possibilities of carrying out the process are represented in FIGS. 1 4.
  • FIGS. 1 3 illustrate various possibilities of measuring the density distribution in a photographic original copy.
  • the simplest embodiment is illustrated in FIG. 1.
  • the method shown in FIG. 1 comprises the uses a source of light 1, the original 2, the screen 3 and the photographic material 4 in which the density distribution is recorded.
  • Original, screen and photographic material are in contact with each other.
  • FIGS. 2 and 3 illustrate embodiments in which an enlarger 5 is used.
  • the original 2 is enlarged by means of the enlarger 5 and recorded in the photographic layer 4 through the screen 3.
  • the screen and photographic material are in contact with each other.
  • FIG. 3 is similar to that in FIG. 2 but in this case an enlarged copy of the screen 3 is reproduced on the photographic layer through the original 2.
  • FIG. 4 shows an embodiment for directly recording the brightness distribution of various sources of light on a photographic film, e.g., for the measurement of sources of illumination, for the measurement of scattered light, for light measurement problems, etc.
  • 6 represents the luminous surface which is to be measured and 7 the camera.
  • the photographic material 4 is situated inside the camera. It is exposed through the screen 3 which is in contact with it.
  • the photographic material need not necessarily be exposed simultaneously to the screen and the original which is to be measured. For instance it is also possible to expose the light-sensitive layer first to the screen and thereafter to the original.
  • the light-sensitive material onto which is already recorded the screen pattern can be stored and used a long time after for measurements according to the invention. This is advantageous since it simplifies the measurements. If an already screened lightsensitive material is used then the exposure time for the measurement is substantially shortened. In this embodiment it is preferred to record a positive screen on the light-sensitive material.
  • any type of photographic screens may be used for the process according to the invention, provided the density distribution of the screen dots is continuous.
  • the usual photoengraving screens or contact screens used for printing processes, for example, are suitable for this purpose. It is preferred to use contact screens because in contrast to photoengraving screens they can be brought into contact with the photographic layers, processing being thereby considerably simplified.
  • the process according to the invention enables the total brightness or density distribution of an object to be measured by means of a single photographic operation consisting of exposure and photographic processing to equidensities.
  • the areas of different brightness or density are distinguished from each other by different symbols, e.g., points, circles, circular areas, square areas, squares, and the like.
  • the completed picture is similar in appearance to the printed digital density distributions obtained with the very expensive digitisers (e.g. Zeisss Zytoscan) except that in the latter case figures or letters are printed instead of symbols.
  • the density symbols can immediat'ely be associated with the corresponding densities of the original.
  • a complete photometry of the original is therefore obtained as a result of only one exposure and photographic processing or recopying of an original photographic copy.
  • illumination measurements e.g., as illustrated in FIG. 4.
  • the density of the original is relatively high, only a relatively low density of the screen dot is then added in order to fonn the constant value of D Conversely, if the density of the original is relatively low, a plane of relatively high density of the screen dot is added to form the constant value of the total density D That means, for a distinct density of the original o i appears a distinct density of the screen (D as equidensity which has the form of distinct symbols.
  • This principle of the process of the invention is illustrated in FIG. 5.
  • the density of the original or of the screen dot is plotted as axis of ordinates against the axis of abscisses, the two densities being one above the other.
  • the areas I, II and III represent steps of different density in the original, the density values of which are 0.6, 0.4 and 0.2.
  • the total density D for a given exposure time is 0.7.
  • the equidensity of the density D 0.1 appears in that area of the photographic material which corresponds to the density step I (D 0.6)
  • the equidensity of the density D 0.3 appears at the step II (D 0.4)
  • the equidensity of the density D 0.5 appears at step III (D 0.2).
  • Equidensities from different density levels of the screen dot are therefore obtained locally separated from each other. These equidensity areas are represented by different symbols which depend on the form of the recorded density plane of the screen dot. This is indicated in FIG. 5 by the broken contour lines around the density mountains which are intended to represent the different recorded density levels of the screen dot.
  • the contrast range of an original or the brightness difference which can be covered by this method depends on the density range of the screen dot and also corresponds to this.
  • a screen with a correspondingly high density range should be used, and for an original with a lower contrast range a screen with a correspondingly lower density range should be used.
  • the smaller the density range of the screen dot therefore, the smaller will be the density range detected in the original and the more accurate will be the possibility of distinguishing small difference of density in the original, and conversely.
  • the size and appearance of the symbols depends on the size and nature of the screen dot and of the line frequency of the screen.
  • the line frequency of the screen should be chosen according to the size of the detail of an original which is required to be examined photometrically.
  • a further subdivision of the symbols and hence the possibility of finer differentiation of small differences in density can be achieved by producing second order equidensities. This is done by producing equidensities from equidensities of the first order (first exposure on equidensity material) by the usual methods.
  • a foil which does not have dots with graduated density distribution but various symbols each of which has a certain density.
  • the different symbols may have clearly distinguishable shapes, e.g. stars, triangles, squares, crosses, letters or numbers etc.
  • a certain number of symbols are chosen, e.g. ten symbols which differ from each other by a density of 0.1. All the different symbols should then be grouped adjacent to each other in the most advantageous arrangement. The size of these groups determines the resolution.
  • This foil may then be used instead of a screen. Again, an equidensity material is exposed, preferably the equidensity film according to German Offenlegungsschrift No. 1,597,509.
  • a particular density of the original or a particular brightness is then always reproduced transparently as equidensity by the same symbol, and the other symbols of the group then do not occur or only those which have an adjacent density. This depends on the desired width of the equidensity.
  • a family of equidensities is therefore obtained after exposure, all the 0.1 density units of the original being characterised by one particular symbol.
  • the density or brightness analysis obtained is not continuous as in the case of screens but is stepwise and the boundaries of adjacent areas can be detected.
  • screen is used quite generally to mean conventional screen as well as elements which are equivalent to them in their effect, such as the symbol foils described above.
  • a photographic material such as that described in German Offenlegungsschrift No. 1,597,509 is advantageously used for the process according to the invention.
  • This material preferably contains a major proportion, up to about 99 percent by weight, of a relatively highly sensitive silver chloride gelatine emulsion and a minor proportion, up to about 25 percent by weight, of a relatively insensitive silver bromide emulsion.
  • the absolute sensitivity of the silver chloride emulsion to light to which the layer is to be exposed should only be slightly less than that of the silver bromide emulsion. Sensitivity ratios of the silver chloride emulsion to the silver bromide emulsion with respect to white light of from 1:10 to 9:10 have been found to be especially suitable.
  • the emulsions have different spectral sensitivity. It is preferred to use emulsions which contain development nuclei such as those conventionally used e.g., in image receiving layers for the silver salt diffusion process. Suitable development nuclei are e.g., finely divided metals, especially silver or their sulfides and/or selenides. After exposure, the material is developed according to the principle of the bromine ion diffusion process with a developer which is substantially free from potassium bromide. Details about this material may be found in the German Offenlegungsschrift mentioned above.
  • the developers have the usual composition used for the bromine ion diffusion process.
  • suitable developer substances Hydroquinone, developers of the aminophenol series, e.g., p-methylaminophenol and p-phenylenediamine derivatives, developers of the pyrazolidone series, e.g., l-phenylpyrazolidone-3, and others, alone or in combination with each other.
  • the potassium bromide content should not exceed 50 mg/l.
  • a suitable silver halide solvent is e.g., sodium sulfite used in concentration of about 1 to 150 g/l of developer.
  • silver halide solvents may be omitted in cases where the developer substance or other additives are themselves capable of functioning as silver halide solvents, as in the case of p-phenylenediamine or its derivatives.
  • the developers also contain the usual additions of water softeners, antioxidants, substances which render the material alkaline, etc.
  • the pH of the developer is between about 8.5 211151 125.
  • EXAMPLE 1 A silver chloride gelatine emulsion is mixed with a silver bromide gelatine emulsion in the ratio of 20:1. The sensitivity of the silver bromide emulsion is 1DIN above that of the silver chloride emulsion. Both emulsions are prepared by the usual methods. 0.06 g of colloidal silver selenide which has been precipitated in gelatine solution are added to 1 litre of this mixture as de- Water I Hydroquinone Ethylcnediaminotctracetic acid 1 l Phenyl-pyrazolidone-il 0.
  • EXAMPLE 2 A high contrast silver chloride emulsion which has been sensitized to the green region of the spectrum with a sensitizer of the following formula:
  • the sensitivity to white light (2,800K) of the sensitiz ed silver chloride emulsion is 1/10 of the sensitivity of the silver bromide emulsion.
  • the emulsion inixture is cast on a support of polyethylene terephthalate (application approximately 4 g of silver per m) Very broad equidensities with steep flanks are obtained after exposure to white light and development as described in Example 1. If the film is exposed behind a yellow filter, the equidensities become progressively narrower with increasing filter density.
  • the width of the equidensities can be varied from a maximum exposure range of 1:10 to a very small exposure range of about l:l.2 by choosing suitable yellow filter densities.
  • the photographic layer is inserted in a camera in contact with a contact screen, as illustrated in FIG. 4.
  • the projector is directed to a white wall.
  • the resulting illuminated area is directly recorded on the film by the camera through the raster.
  • the equidensity range can now be adjusted to its optimum value by suitable choice of a yellow filter which may be arranged e.g., in front of the object lens.
  • EXAMPLE 3 The photographic material of Example 2 is exposed in a contact copying device to a contact screen using white light (color temperature 2,800K) to produce a positive pattern of the contact screen in the lightsensitive silver halide emulsion layer.
  • That material which contains the positive image of the contact screen in form of a latent image is used as described in Example 2 for measuring the illumination of a projector with the difference that the camera contains only the light-sensitive material and not a contact screen.
  • a process for photographically showing the digital distribution of brightness or density comprises exposing a light sensitive photographic material with at least one silver halide emulsion layer to the object whose brightness or density distribution is to be measured and to a photographic screen of spots each having a continuous range of densities, and then processing the exposed material to produce equidensities in which the spots have appearances that differ in accordance with the local density of the object.
  • a process for photographically showing the digital distribution of brightness or density comprises exposing a light-sensitive photographic material with at least one silver halide emulsion layer to the object whose brightness or density distribution is to be measured and to a raster of spots each having a range of densities in which different density levels have different characteristic shapes, and then processing the exposed material to produce equidensities in which the spots have appearances that differ in accordance with the local density of the object.
US00162415A 1970-07-18 1971-07-14 Photographic process Expired - Lifetime US3779755A (en)

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DE2035798A DE2035798C3 (de) 1970-07-18 1970-07-18 Photographisches Verfahren

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US (1) US3779755A (de)
BE (1) BE769749A (de)
CA (1) CA971413A (de)
CH (1) CH560917A5 (de)
DE (1) DE2035798C3 (de)
FR (1) FR2103040A5 (de)
GB (1) GB1321370A (de)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19606603A1 (de) * 1996-02-22 1997-08-28 Beck Bernhard Verfahren zur Ausfiltrierung der intensivsten Strahlungserscheinung auf einer bestimmten Fläche innerhalb einer bestimmten Zeit

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3143420A (en) * 1960-11-14 1964-08-04 Eastman Kodak Co Prescreening film by clayden and herschel exposure
US3164470A (en) * 1958-12-27 1965-01-05 Agfa Ag Contact screens for reproduction photography
US3637388A (en) * 1967-12-18 1972-01-25 Agfa Gevaert Ag Process for the photographic production of equidensities

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3164470A (en) * 1958-12-27 1965-01-05 Agfa Ag Contact screens for reproduction photography
US3143420A (en) * 1960-11-14 1964-08-04 Eastman Kodak Co Prescreening film by clayden and herschel exposure
US3637388A (en) * 1967-12-18 1972-01-25 Agfa Gevaert Ag Process for the photographic production of equidensities

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CA971413A (en) 1975-07-22
DE2035798A1 (de) 1972-02-03
DE2035798B2 (de) 1978-05-24
GB1321370A (en) 1973-06-27
CH560917A5 (de) 1975-04-15
BE769749A (de) 1972-01-10
FR2103040A5 (de) 1972-04-07
DE2035798C3 (de) 1979-01-11

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