US3127268A - Hellmig - Google Patents

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US3127268A
US3127268A US3127268DA US3127268A US 3127268 A US3127268 A US 3127268A US 3127268D A US3127268D A US 3127268DA US 3127268 A US3127268 A US 3127268A
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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

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  • E 4'00 500 600 my LOG l-T INVENTOR.
  • the present invention relates to a process for the tone correction of black-and-White or monochromatic photographic images.
  • tone defects which are shown in the defective portrayal of the high-lights and/or shadows.
  • Processes for overcoming these defects are known; the essence thereof consists in the combination of the normal print requiring correction with a separate black-and-white image or print of the same original, which contains only the correction of a certain type of tones or or" several types of tones simultaneously, it being possible for several tone masks, for example high light masks and shadow masks, to be combined in one combined tone mask or to be present as separate individual masks (compare German patent specifications 505,447, 529,371, 715,654, 731,244, 888,- 362, and U8. patent specification 2,544,910).
  • tone separation record in the correct density is combined with certain difficulties and. represents a routine operation, since it depends on the subject of the exposure, for example, its nature, brightness or gradation; therefore such a mask must be repeated or after-treated in many cases, for example if it has been too weakly exposed or developed too flatly.
  • the tone correction of black-and-white or monochromatic images can be essentially simplified and the said disadvantages can be overcome if the black-and-white or monochromatic images are combined with a colored tone-separation record and copied.
  • the tone mask can be made effective at full strength of hardness, or it can have no efiect at all or be effective with all possible intermediate stages, depending on the choice of the copying or exposure light. It is thus possible for the effect of a mask which is perhaps too strong, too hard or perhaps over-exposed to be reduced as desired, without having to effect a reduction of the mask by chemical after-treatment.
  • any desired color can be chosen for the tone mask, provided only that this color has a more strongly absorbing and a less strongly absorbing range within the spectrum, that is to say, is not neutral grey in color.
  • Particularly suitable are such colors in which the difference between maximum and minimum spectral absorption is as great as possible and which therefore are especially saturated and bright, as is the case for ex ample with colors such as magneta, blue-green, red, green or violet, since with these particularly large modifications in the hardness of the mask are possible. Less pronounced colors can if necessary also be used, depending on the position of the practical case in this respect.
  • the degree of hardness of the tone-separation record is adjusted as desired, depending on the ratio between the two colors blue and green or red (FIGURE 1, curves 1) and c), it being presupposed that the light-sensitive material on to which the mask is to be further copied is also sensitive to green and/ or red light as well as to blue light.
  • Examples for corresponding color filters namely blue and green filters, are represented in FIGURE 2 in the form of spectral transmission curves a to d.
  • the successive exposure with suitable amounts of blue and green light is equivalent to the exposure through such a filter.
  • FIG- URE 3 The co-operation of a normal continuous tone image and a color tone separation record when they are printed after being brought in printing register is shown in FIG- URE 3.
  • the eificacy of the yellow tone separation records according to FlGURES lad in the continuous tone image is clearly apparent in this FIGURE 13.
  • the invention is not limited to separate tone separation records; such a color tone separation record can also be inseparably combined with the normal-tone image.
  • This case can be achieved for example by a suitable twolayer material; in this connection, the layers can either be cast one above the other, if necessary separated by a filter layer, or for example for the purpose of making possible separate treatments (etching, developing), they can also be arranged on different sides of the support.
  • these layers can be sensitive for differently colored light.
  • the light-sensitive half-tone layer can be green-sensitive for the normal-tone image, while the layer for the tone separation record can be blue-sensitive.
  • the normal-tone image and the tone separation record are preferably differently colored. Due to the kind of light used with the printing of such a material, each of the two images can be independently influenced, so that both the hardness of the continuous tone image and the hardness of the mask can be influenced as required and independently of one another. It is thus possible without special technical aids to carry out a socalled additive masking, such as that which forms the basis, for example, of the known tone-separation process according to Person.
  • the only condition to be observed in the process is that the two dyestuffs have separate absorption and permeability zones in the spectrum, although a partial overlapping of these zones does not prevent the process being carried into efiect.
  • Such pairs of dyestuffs are sufiiciently Well known from three-color photography on multi-layer material: for example, yellow/blue green or yellow/magenta or magneta/blue-green.
  • the former can be copied with green light and the latter with blue light separately from one another on to an orthochromatic material, which is sensitive to blue and green.
  • a silver halide layer which contains a comparatively insensitive color coupler. After the exposure and the color development of such a material, a black-and-White continuous tone image is formed, this image representing the normal tone image and being super-imposed by a color image which is iormed only at the places where the exposure is high ad which represents the tone-separation record. If necessary, the black-and-white continuous image can be further intensified by using a non-color-coupling developer, used separately or simultaneously in admixture with the color developer.
  • the coloring of the masks can take place according to any suitable processes; color development, silver colorbleaching processes and mordant processes are to be mentioned as examples thereof.
  • Example 1 On a transparent support there is coated a silver bromide-gelatine emulsion, which is sensitized for the green part of the visible spectrum and which contains a conpler -for the production of a magenta color image by the process of color forming development g. of 1(4'- phenoxy 3 sulphophenyl)-3-stearyl-5'pyrazolone per 1 liter).
  • a second silver halide layer is coated which is not optically sensitized and which has a sensitivity that is of that of the inner layer.
  • a coupler for the production of a yellow color image by the process of color forming development is incorporated (15 g. of p-stearoyl-aminobenzoyl-acetanilide-3,5-dicarboxylic acid per 1 liter of emulsion).
  • This material is exposed in a camera to a black-andwhite half-tone image, thereafter it is developed for 5 minutes in an ordinary color forming developer solution (p-diethyl-aminoaniline being the developer substance) washed, bleached and fixed and finally washed.
  • an ordinary color forming developer solution p-diethyl-aminoaniline being the developer substance
  • the emulsions for said two-layer material must fulfill the following conditions:
  • the magenta image produced in the inner layer should have a gradation of 1.3 when measured behind a green filter the transmittance of which lies in the region between 500 and 600 mu, whereas the yellow image of the upper layer (tone-mask) should have a gradation of 3.2 when measured behind a blue filter, the transmittance of which lies between 400 and 500 m
  • This image, representing a combined continuous tone image and masking image is printed onto an orthochromatic silverhalide layer in two steps, for the first step blue printing light and for the second step green printing light being used.
  • the eficiency of the masking image may be varied by varying the proportion of exposure times behind the blue and green filters respectively.
  • the same etfect may be achieved if the same two-layer material is used which, however, does not contain a coupler in the inner layer.
  • the material is not bleached after development but only fixed, whereby a silver image and a silver plus dyestuif image are obtained in the inner and outer layer respectively.
  • Example 2 A -black-and-white continuous tone image on a paper support is exposed to a silver halide layer coated on a transparent support and processed to a blaclt-and-white silver image with a contrast of 1.4.
  • Example 3 A multi-color negative is printed through a green filter onto two sheets of a photographic material consisting of an orthochromatic silver halide layer coated on a transparei support. The exposure times are the same as in Example 2.
  • a developer which contains a coupler for the production of a cyan image, whereby a cyan shadow mask is obtained in the one material, whereas a blackand-white half-tone image is otbained in the other material.
  • the two images after being brought in register, are printed through a screen onto a panchromatic silver halide layer, the exposure being made through a red filter (transmission above 580 mg) and then through a green filter (transmission about 480 to 600 m
  • the screened print is developed, fixed, Washed and dried. It may be used as a copy for the production of a printing plate for printing the red partial image in a multi-color printing process.
  • Example 4 A black-and-white diapositive having a contrast of 1.5 is printed by means of a light source emitting ultra-violet light onto a light sensitive diazo layer as it is put on the market by the firm Katie & Co. under the trade name Ozachrom. The exposure is such that after development a yellow image of the high lights only is obtained (shadow mask). The diapositive and the yelloW shadow mask are brought in register and printed onto a carbon tissue (pigment paper).
  • the process of producing tone-corrected photographic copies of an original which comprises providing a normal monochrome photographic image of said origi nal, which image is defective in that it has too short a range of gradation in the highlights of the original, providing a dyestuff image of essentially only the highlights of the original, having the same sign as the monochrome image, and having a spectral range in one color portion of the spectrum, which portion is different from that in which there is any maximum absorption of the monochrome image, combining the images, printing said combined images onto a light-sensitive silver halide layer by means of a printing light selected to be absorbed by both of the images, and adjusting the printing light to cause the monochrome image to be printed and to cause the dyestuff image to be printed to a predetermined degree along with the monochrome image and provide print highlights with a steeper gradation than from the monochrome image alone.

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  • Silver Salt Photography Or Processing Solution Therefor (AREA)

Description

March 31, 964 E. HELLMIG 3,127,268
TONE CORRECTION OF PHOTOGRAPHIC IMAGE Filed March 15, 1956 b FIG] L06 l-T a d z- S 3 F/G.2 g
E 4'00 500 600 my LOG l-T INVENTOR. EHRHARD HE LLM/G A T TORNEYS United States Patent TGNE CGRRECTKGN OF PHQTfif-RAEPl-HQ llviAQ-E Ehrhard Helhnig, Levcrhnsen, Germany, assignor to Agin Alrtiengesellschait, Leverhuscn, Germany, a corporation of Germany Filed Mar. 155, i955, Ser. No. 57l,7*3 (ll-aims priority, application Germany Mar. 19, 1955 8 Claims. ill. 96-44) The present invention relates to a process for the tone correction of black-and-White or monochromatic photographic images.
It is known that black-and-white or monochromatic photographic images, particularly in the reproduction art (also color separation records) are affected by so-called tone defects, which are shown in the defective portrayal of the high-lights and/or shadows. Processes for overcoming these defects are known; the essence thereof consists in the combination of the normal print requiring correction with a separate black-and-white image or print of the same original, which contains only the correction of a certain type of tones or or" several types of tones simultaneously, it being possible for several tone masks, for example high light masks and shadow masks, to be combined in one combined tone mask or to be present as separate individual masks (compare German patent specifications 505,447, 529,371, 715,654, 731,244, 888,- 362, and U8. patent specification 2,544,910).
The production of a tone separation record in the correct density is combined with certain difficulties and. represents a routine operation, since it depends on the subject of the exposure, for example, its nature, brightness or gradation; therefore such a mask must be repeated or after-treated in many cases, for example if it has been too weakly exposed or developed too flatly.
It has now been found that the tone correction of black-and-white or monochromatic images can be essentially simplified and the said disadvantages can be overcome if the black-and-white or monochromatic images are combined with a colored tone-separation record and copied. By this means, the tone mask can be made effective at full strength of hardness, or it can have no efiect at all or be effective with all possible intermediate stages, depending on the choice of the copying or exposure light. It is thus possible for the effect of a mask which is perhaps too strong, too hard or perhaps over-exposed to be reduced as desired, without having to effect a reduction of the mask by chemical after-treatment.
Any desired color can be chosen for the tone mask, provided only that this color has a more strongly absorbing and a less strongly absorbing range within the spectrum, that is to say, is not neutral grey in color. Particularly suitable are such colors in which the difference between maximum and minimum spectral absorption is as great as possible and which therefore are especially saturated and bright, as is the case for ex ample with colors such as magneta, blue-green, red, green or violet, since with these particularly large modifications in the hardness of the mask are possible. Less pronounced colors can if necessary also be used, depending on the position of the practical case in this respect.
The process is to be explained by way of example by reference to the accompanying figures.
For example, if the mask is produced in the color yellow, this has its greatest hardness or eificiency in connection with blue printing light, as represented by curve a in FIGURE 1. With green printing light, on the other hand, it is without any effect, since the color yellow is permeable to green light (FIGURE 1, curve (I). The same also applies for red or yellow light or green plus red light. By using mixed blue and green "ice light in the printing of the yellow-colored tone-separation record, it is then possible for the degree of hardness of the tone-separation record to be adjusted as desired, depending on the ratio between the two colors blue and green or red (FIGURE 1, curves 1) and c), it being presupposed that the light-sensitive material on to which the mask is to be further copied is also sensitive to green and/ or red light as well as to blue light.
Examples for corresponding color filters, namely blue and green filters, are represented in FIGURE 2 in the form of spectral transmission curves a to d. The successive exposure with suitable amounts of blue and green light is equivalent to the exposure through such a filter.
The co-operation of a normal continuous tone image and a color tone separation record when they are printed after being brought in printing register is shown in FIG- URE 3. The eificacy of the yellow tone separation records according to FlGURES lad in the continuous tone image is clearly apparent in this FIGURE 13.
The invention is not limited to separate tone separation records; such a color tone separation record can also be inseparably combined with the normal-tone image. This case can be achieved for example by a suitable twolayer material; in this connection, the layers can either be cast one above the other, if necessary separated by a filter layer, or for example for the purpose of making possible separate treatments (etching, developing), they can also be arranged on different sides of the support. In order that it may be possible for the separate layers of the print to be exposed independently of one another, these layers can be sensitive for differently colored light. For example, the light-sensitive half-tone layer can be green-sensitive for the normal-tone image, while the layer for the tone separation record can be blue-sensitive.
In a further modification of this embodiment, the normal-tone image and the tone separation record are preferably differently colored. Due to the kind of light used with the printing of such a material, each of the two images can be independently influenced, so that both the hardness of the continuous tone image and the hardness of the mask can be influenced as required and independently of one another. It is thus possible without special technical aids to carry out a socalled additive masking, such as that which forms the basis, for example, of the known tone-separation process according to Person. The only condition to be observed in the process is that the two dyestuffs have separate absorption and permeability zones in the spectrum, although a partial overlapping of these zones does not prevent the process being carried into efiect. Such pairs of dyestuffs are sufiiciently Well known from three-color photography on multi-layer material: for example, yellow/blue green or yellow/magenta or magneta/blue-green.
For example, if the normal-tone layer is magenta and the tone separation record is yellow, the former can be copied with green light and the latter with blue light separately from one another on to an orthochromatic material, which is sensitive to blue and green.
The following additional embodiments are also possible: As light-sensitive record material, a silver halide layer is used which contains a comparatively insensitive color coupler. After the exposure and the color development of such a material, a black-and-White continuous tone image is formed, this image representing the normal tone image and being super-imposed by a color image which is iormed only at the places where the exposure is high ad which represents the tone-separation record. If necessary, the black-and-white continuous image can be further intensified by using a non-color-coupling developer, used separately or simultaneously in admixture with the color developer.
enemas The coloring of the masks can take place according to any suitable processes; color development, silver colorbleaching processes and mordant processes are to be mentioned as examples thereof.
The same effect can be produced by the exposed lightsensitive material being developed with a black-and-white developer of such a qualitative composition that a colored image designated as a so-called residual image is simultaneously formed in the higher densities (highlights) in addition to the silver. Such developers and developer compositions are sufiiciently well known. Developers suitable for these purposes are: alkaline aqueous solutions of developer substances of the dihydroxyand trihydroxy benzene group, such as for example pyrocatechol, hydroquinone, chlorohydroquinone, pyrogallol.
*Instead of the black-and-white half-tone image, it is again also possible have a colored image, it being possible for the colors of the two images again to show a common absorption range (subtractive masking) or separate absorption ranges.
Example 1 On a transparent support there is coated a silver bromide-gelatine emulsion, which is sensitized for the green part of the visible spectrum and which contains a conpler -for the production of a magenta color image by the process of color forming development g. of 1(4'- phenoxy 3 sulphophenyl)-3-stearyl-5'pyrazolone per 1 liter).
On this layer a second silver halide layer is coated which is not optically sensitized and which has a sensitivity that is of that of the inner layer. into the outer layer a coupler for the production of a yellow color image by the process of color forming development is incorporated (15 g. of p-stearoyl-aminobenzoyl-acetanilide-3,5-dicarboxylic acid per 1 liter of emulsion).
This material is exposed in a camera to a black-andwhite half-tone image, thereafter it is developed for 5 minutes in an ordinary color forming developer solution (p-diethyl-aminoaniline being the developer substance) washed, bleached and fixed and finally washed.
The emulsions for said two-layer material must fulfill the following conditions: The magenta image produced in the inner layer (continuous tone image) should have a gradation of 1.3 when measured behind a green filter the transmittance of which lies in the region between 500 and 600 mu, whereas the yellow image of the upper layer (tone-mask) should have a gradation of 3.2 when measured behind a blue filter, the transmittance of which lies between 400 and 500 m This image, representing a combined continuous tone image and masking image is printed onto an orthochromatic silverhalide layer in two steps, for the first step blue printing light and for the second step green printing light being used. The eficiency of the masking image may be varied by varying the proportion of exposure times behind the blue and green filters respectively.
The same etfect may be achieved if the same two-layer material is used which, however, does not contain a coupler in the inner layer. In this case the material is not bleached after development but only fixed, whereby a silver image and a silver plus dyestuif image are obtained in the inner and outer layer respectively.
Example 2 A -black-and-white continuous tone image on a paper support is exposed to a silver halide layer coated on a transparent support and processed to a blaclt-and-white silver image with a contrast of 1.4.
Thereafter a second exposure is made on another sil ver halide layer of the same type as before, however, the exposure is made so short that only the high-lights of the original are reproduced. After development in an ordinary color forming developer containing a coupler for the production of a magenta color image washing,
fixing, bleaching, washing and drying a high light tone mask is obtained.
Both images are brought in register and the combined images are printed onto an orthochromatic silver halide layer as disclosed in Example 1.
Example 3 A multi-color negative is printed through a green filter onto two sheets of a photographic material consisting of an orthochromatic silver halide layer coated on a transparei support. The exposure times are the same as in Example 2. For the development of the masking image a developer is used which contains a coupler for the production of a cyan image, whereby a cyan shadow mask is obtained in the one material, whereas a blackand-white half-tone image is otbained in the other material.
The two images, after being brought in register, are printed through a screen onto a panchromatic silver halide layer, the exposure being made through a red filter (transmission above 580 mg) and then through a green filter (transmission about 480 to 600 m The screened print is developed, fixed, Washed and dried. It may be used as a copy for the production of a printing plate for printing the red partial image in a multi-color printing process.
Example 4 A black-and-white diapositive having a contrast of 1.5 is printed by means of a light source emitting ultra-violet light onto a light sensitive diazo layer as it is put on the market by the firm Katie & Co. under the trade name Ozachrom. The exposure is such that after development a yellow image of the high lights only is obtained (shadow mask). The diapositive and the yelloW shadow mask are brought in register and printed onto a carbon tissue (pigment paper).
What I claim is:
l. The process of producing tone-corrected photographic copies of an original which comprises providing a normal monochrome photographic image of said origi nal, which image is defective in that it has too short a range of gradation in the highlights of the original, providing a dyestuff image of essentially only the highlights of the original, having the same sign as the monochrome image, and having a spectral range in one color portion of the spectrum, which portion is different from that in which there is any maximum absorption of the monochrome image, combining the images, printing said combined images onto a light-sensitive silver halide layer by means of a printing light selected to be absorbed by both of the images, and adjusting the printing light to cause the monochrome image to be printed and to cause the dyestuff image to be printed to a predetermined degree along with the monochrome image and provide print highlights with a steeper gradation than from the monochrome image alone.
2. Process according to claim 1, wherein the dyestut'f image is inseparably combined with the detective photographic image.
3. Process according to claim 1, wherein the dyestufl image and the monochrome separate image are carried by supports.
4. Process according to claim 2, wherein the detective image and the dyestuif image are contained in a common layer.
5. Process according to claim 1, wherein the defective image is a black-and-white image.
6. Process according to claim 1, wherein the defective image is a blacl and-white image and the dystufr" image is combined with a corresponding silver image.
7. Frocess according to claim 1, wherein the dyestuff image is a color-developed image.
8. Process according to claim 1, wherein the printing 5 6 of the normal image and of the dyestufi image is carried 2,294,981 Hanson Sept. 8, 1945 out in separate steps. 2,455,849 Yule Dec. 7, 1948 2,533,452 Glasoe et a1 Dec. 12, 1950 References Cited in the file of this patent 2,544,910 Yule Mar. 11, 1951 UNITED STATES PATENTS 5 2,737,457 Childress Mar. 6, 1956 1,954,335 Seymour Apt 10, 1934 2,848,326 Whltmore 19, 1958 2,193,931 Michaelis Mar. 19, 1940 OTHER REFERENCES 2,241,413 Mich'flelis Y 13, 1941 Niblette: Photography-Its Materials and Processes 2,338,661 M9rrls T 4, 1944 m fifth ed., 1952, pages 480-481. (Copy in Div. 60.) 2,347,119 Mlchaells P 18, 1944 Lester: Photo Lab Index, vol. 2, 1952, pages 16-87 2,378,213 Glasoe J n 12, 1945 n 1 3, (Copy i 0.

Claims (1)

1. THE PROCESS OF PRODUCING TONE-CORRECTED PHOTOGRAPHIC COPIES OF AN ORIGINAL WHICH COMPRISES PROVIDING A NORMAL MONOCHROME PHOTOGRAPAHIC IMAGE OF SAID ORIGINAL, WHICH IMAGE IS DEFECTIVE IN THAT IT HAS TOO SHORT A RANGE OF GRADATION IN THE HIGHLIGHTS OF THE ORIGINAL, PROVIDING A DYESTUFF IMAGE OF ESSENTIALLY ONLY THE HIGHLIGHTS OF THE ORIGINAL, HAVING THE SAME SIGN AS THE MONOCHROME IMAGE, AND HAVING A SPECTRAL RANGE IN ONE COLOR PORTION OF THE SPECTRUM, WHICH PORTION IS DIFFERENT FROM THAT IN WHICH THERE IS ANY MAXIMUM ABSORPTION OF THE MONO-
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3411905A (en) * 1965-06-14 1968-11-19 Eastman Kodak Co Photographic masking process

Citations (12)

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Publication number Priority date Publication date Assignee Title
US1954335A (en) * 1931-10-29 1934-04-10 Eastman Kodak Co Control of contrast with color developers
US2193931A (en) * 1936-03-24 1940-03-19 Bela Gaspar Process for producing multicolored photographic images
US2241413A (en) * 1937-03-23 1941-05-13 Chromogen Inc Photographic printing process and image for use therein
US2294981A (en) * 1940-05-25 1942-09-08 Eastman Kodak Co Color correction
US2338661A (en) * 1942-08-15 1944-01-04 Eastman Kodak Co Photographic tone correction mask
US2347119A (en) * 1939-11-15 1944-04-18 Chromogen Inc Process for producing photographic multicolor pictures
US2378213A (en) * 1944-01-07 1945-06-12 Eastman Kodak Co Photographic tone correction mask
US2455849A (en) * 1944-03-11 1948-12-07 Eastman Kodak Co Photographic unsharp masking method
US2533452A (en) * 1947-06-18 1950-12-12 Eastman Kodak Co Photographic brightness correction mask
US2544910A (en) * 1947-10-09 1951-03-13 Eastman Kodak Co Tone control in photography
US2737457A (en) * 1952-11-22 1956-03-06 Jerome Flax Photographic method of tonal scale compensation
US2848326A (en) * 1955-09-26 1958-08-19 Eastman Kodak Co Method for preparing masked images

Patent Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1954335A (en) * 1931-10-29 1934-04-10 Eastman Kodak Co Control of contrast with color developers
US2193931A (en) * 1936-03-24 1940-03-19 Bela Gaspar Process for producing multicolored photographic images
US2241413A (en) * 1937-03-23 1941-05-13 Chromogen Inc Photographic printing process and image for use therein
US2347119A (en) * 1939-11-15 1944-04-18 Chromogen Inc Process for producing photographic multicolor pictures
US2294981A (en) * 1940-05-25 1942-09-08 Eastman Kodak Co Color correction
US2338661A (en) * 1942-08-15 1944-01-04 Eastman Kodak Co Photographic tone correction mask
US2378213A (en) * 1944-01-07 1945-06-12 Eastman Kodak Co Photographic tone correction mask
US2455849A (en) * 1944-03-11 1948-12-07 Eastman Kodak Co Photographic unsharp masking method
US2533452A (en) * 1947-06-18 1950-12-12 Eastman Kodak Co Photographic brightness correction mask
US2544910A (en) * 1947-10-09 1951-03-13 Eastman Kodak Co Tone control in photography
US2737457A (en) * 1952-11-22 1956-03-06 Jerome Flax Photographic method of tonal scale compensation
US2848326A (en) * 1955-09-26 1958-08-19 Eastman Kodak Co Method for preparing masked images

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3411905A (en) * 1965-06-14 1968-11-19 Eastman Kodak Co Photographic masking process

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