US3281242A

US3281242A - Multigeneration photographic printing

Info

Publication number: US3281242A
Application number: US344254A
Authority: US
Inventors: Robert H Sprague; Morris C Roscow
Original assignee: Horizons Inc
Current assignee: Horizons Inc
Priority date: 1964-02-12
Filing date: 1964-02-12
Publication date: 1966-10-25
Anticipated expiration: 1983-10-25
Also published as: GB1083734A; NL6414006A; DE1547933A1; BE659686A

Description

United States Patent 3,281,242 MULTIGENERATION PHOTOGRAPI-IIC PRINTING Robert H. Sprague, Chagrin Falls, and Morris C. Roscow, Cleveland, Ohio, assignors to Horizons Incorporated, a corporation of New Jersey No Drawing. Filed Feb. 12, 1964, Ser. No. 344,254 5 Claims. (Cl. 96-27) This inVentiOn relates to the reproduction of silver halide negatives by procedures whereby the final product whether in the form of a negative or a positive image possesses a desired degree of contrast and a desired gamma.

Although impressive advances have been made in such diverse fields as aerial photography used for reconnaissance and X-ray photography used in the diagnosis and treatment of human diseases, one of the problems which continues to impair the utility of the processes developed is that although the film record contains all of the desired information, the information is difficult to read out either because of too low contrast or too high contrast.

Often when efiorts have been made to improve the contrast an undesirable loss in resolution has accompanied desired improvements in contrast, e.g. as described in an article by Berg published in Photographic Science and Engineering, Volume 5, No. 6, December 1961, pages 321-326.

The principal object of this invention is to provide a procedure for reproducing silver halidefilm negatives.

whereby a multigeneration print is obtained in which both the contrast and the gamma (the slope on the H and D curve) are each approximately 1 for optimum readout of the information on the original negative.

Other objects will become apparent from the description which follows.

By the practice of the present invention it has been found possible to attain a print with the desired amount of contrast and of gamma from negatives which exhibited contrasts which were too low, too high or anywhere be tween these values.

Briefly the procedure consists of the following sequence of steps, starting with a silver halide negative bearing the radiant energy provided by two General Electric sun lamps. This produces the blue second-generation positive print and, depending on the exposure, may produce a change in contrast and gamma or may reproduce the original negative with these characteristics essentially unchanged.

(2) The second step in the procedure is the printing of a third-generation negative image by exposing a suitable photosensitive composition to suitably filtered visible radiation provided by a photoflood lamp, through the blue second-generation print. Thus, .if greater contrast is desired the third-generation exposure should be through a red filter, whereas for lower contrast the exposure should be through a green filter. The photosensitive material utilized for the third-generation print is one based on 3,281,242 Patentedv Oct. 25, 1966 "ice Example 14 of United States Patent 3,109,736, for example. At this point the image is a black negative image.

(3) The next step in the procedure is to print again on the same material so as to obtain the fourth-generation positive copy, of the silver halide negative, considered to be the first-generation copy. Again, use of the proper filter over the exposing light produces further correction in contrast if this is desired.

In the tables which follow there are reported results obtained with three test negatives, one of which originally had high contrast and a high gamma, the second of which was nearly at the desired values of 1.00 and 1.00 for contrast and gamma, and the third of which was well below the desired values for contrast and gamma.

The ultraviolet-sensitive diphenylamine-c-arbon tetrabromide blue-image copy material identified in the tables below as blue image material was prepared as follows: A coating solution was prepared according to the follow ing formula:

Diphenylamine grams 2,025 Methyl isobutyl ketone cc 11,250 Isopropyl acetate cc 4,750 Carbon tetrabromide grams 2,368

This solution was applied by a meniscus coating technique on a roll coating machine to a polyester film base of 3-mil thickness, which had been presubbed with a cellulose ester receptive layer. The solution was absorbed bythe sublayer on the film, the quantity of material taken up being regulated by the speed of travel of the film.

The visible-light-sensitive trinuclear merocyanine base black-image copy material identified in the tables below as black image material was prepared as follows. A coating solution was prepared according to the following formula. (The trinuclear merocyanine base referred to as Dye below has the struture shown):

. o=Z 1lI-oHi( C=OHCH= =CH N S N (51H; I

3-ethyl-5-[ (3-ethyl-2 (3H) benzothiazolylidene) ethylidenel -2- (2-quinolylmethy1ene)-4-thiazo1idone FORMULA Dye grams 225 Methylene chloride liters 12 Leuco crystal violet grams 225 Carbon tetrabromide do 3,150 Methyl ethyl ketone 1iters 12 This solution was machine-coated in the same manner as the previous film onto the same film base.

Prints on the diphenylamine film were fixed by heating in a forced draft oven at C. for 3 minutes and the trinuclear merocyanine base films were fixed by washing three times for 45 seconds each in a mixture consisting of 1 part aoetone+1 part toluene+4 parts petroleum ether.

The following tables summarize the values obtained from the H and D curves plotted for each generation of film after exposure through the indicated filter and to the indicated light source.

r 3 It will be seen that in each instance the desired contrast (AD) of 1.0 and gamma of about 1 had been obtained.

carbon tetrabromide film and then on a trinuclear merocyanine dye base film of the type described in Example 14 of U. S. 3,109,736 (twice in succession), each ex- TABLE I Exposure Conditions Gener- Film D-max. Dmln. AD Gamma ation '7 Filter Lights Time FROM LOW-CONTRAST NEGATIVE Negative 0. 70 0. 19 0. 51 0. 47 Blue Image Materi 1. 55 1 0. 83 0.72 O. 75 Black Image Material- 1. 50 0. 37 1. l3 1. 25 d 1.40 1 0.35 1.05 1.10

Negative 1. 00 0. 08 0. 92 0. 85 Blue Image Material Two GESL- 1. 62 0.37 1. 25 1. 30 Black Image Material One DXC 1. 19 0.17 1. 02 1. 16 1. 37 0. 37 1.00 1.04

Silver Test Negative 1. so 0. 02 1.78 1. 40 Blue Image Material. 1. 47 0. 1. 37 0 90 Black Image Material- 1. 48 0. 18 1. 30 1. d0 1. 22 0. 22 1. 00 1. 08

In another series of tests in which the film materials were treated with the same photosensitive compositions as those in the above described tests, but were exposed to four lamps in order to illuminate an area large enough to include a step tablet plus the aerial photograph negative. The four sun lamps or photoflood lamps were mounted in a square with 11 inch centers and with the bottom of the lamps 12 inches from the exposure plane, the results were as follows:

posure being through any suit-able filter, whereby a final image is obtained which possesses a 7 of about 1 and a contrast of about 1, contrast being the difference between the maximum and minimum density areas of the exposed film.

In this specification, contrast is intended to mean the difference in visual brilliance between one part of an image and another and is proportional to the product of TABLE II Exposure Conditions Gener- Film D-max. D-min. AD Gamma ation '7 Filter Lights Time FROM LOW-CONTRAST NEGATIVE Negative 0. 70 0. 19 0. 51 0. 47 Blue Image Material" Four GESL 2.5 min 1. 24 0. 51 0.73 O. 75 Black Image MateriaL Four DXC. 3 min 1.48 0. 65 0. 83 0. 84 .d0 do 3min 1.20 0.27 0.93 1.05

I Negative 1.00 0. 0S 0. 92 0.85 IL Blue Image Material 1. 22 0.20 1.02 1.02 III Black Image Materi 1. 24 0. 19 1. 05 1. 10 IV..- do 1.30 0.37 0. 93 1. 05

Negative 1 80 O. 02 1. 78 1. Blue Image MateriaL. 1. 36 0. 06 1. 30 1.03 Black Image Material. 1 t6 0. 36 1. 10 1.18 do 1.14 0 20 0. 94 1. oo

Fixing was as in the previous example.

The densities of the step tablet portion of the print were read with a densitometer through an appropriate filter and the results were plotted on a density vs. step curve to illustrate the tonal range achieved with each generation.

It will be seen that the two photosensitive compositions utilized, namely those described in Wainer United States Patent 3,042,515 and those described in United States Patent 3,109,736 are particularly suited to the multigeneration printing process described whereby silver halide negatives exhibiting an unsatisfactory contrast AD and/or 'y may be reprinted first on a diphenylaminetive makes with the horizontal when the density is plotted versus the logarithm of the exposure, i.e. a gamma of 1 is equal to a slope of 45. As explained in Ilford, gamma serves to measure the contrast, i. e. the rate at which density increases as the exposure increases, in the straight line portion of the H-D curve.

We claim:

1. A process for obtaining a negative with a contrast of about 1 and a gamma of about 1 from a negative possessing an image in which at least one of the contrast and the gamma has a value appreciably difierent from unity, which comprises:

(1) printing through the first generation silver halide image on said negative onto a photosensitive film consisting essentially of a mixture of diphenylamine and carbon tetrabromide supported as a thin layer, by exposing said film to a suitable dose of radiant energy in the ultraviolet, through said negative, thereby producing a blue-image second generation positive print;

(2) printing a third generation negative image by exposing a second photosensitive film composition to visible radiation, through said second generation positive print; said second photosensitive film consisting essentially of a mixture of 3-ethyl-5-[ (3-ethyl- 2 (3H)benzothiazolylidene)ethylidene] 2 (2 quinolylmethylene)-4-thiazolidone, Leuco Crystal Violet and carbon tetrabromide supported as a thin layer, thereby producing a black image third generation negative image; and

(3) thereafter printing a fourth generation positive by exposing a photosensitive composition as defined in (2) to a suitable dose of visible radiation through said third generation negative.

2. The process of claim 1 wherein the first generation negative is a low contrast and exposure is successively through unfiltered ultraviolet radiation, red filtered visible light and green filtered visible light to obtain said second, third and fourth generation images.

References Cited by the Examiner UNITED STATES PATENTS 2,202,026 5/ 1940 RenWick 96-27 3,042,515 7/ 1962 Wainer 96-90 3,109,736 11/ 1963 Spraque et al. 9690 OTHER REFERENCES Baines, The Science of Photography, New York, 1958, p. 212.

Berg, Photographic Science and Engineering, vol. 5, No. 6, December 1961, pp. 321-326.

The Focal Encyclopedia of Photography, vol. 1, 1958, p. 261.

Mees, Theory of the Photographic Process, 1954, p. 868.

NORMAN G. TORCHIN, Primary Examiner.

I. RAUBITSOHEK, Assistant Examiner.

Claims

1. A PROCESS FOR OBTAINING A NEGATIVE WITH A CONTRAST OF ABOUT 1 AND A GAMMA OF ABOUT 1 FROM A NEGATIVE POSSESSING AN IMAGE IN WHICH AT LEAST ONE OF THE CONTRAST AND THE GAMMA HAS A VALUE APPRECIABLY DIFFERENT FROM UNITY, WHICH COMPRISES: (1) PRINTING THROUGH THE FIRST GENERATION SILVER HALIDE IMAGE ON SAID NEGATIVE ONTO A PHOTOSENSITIVE FILM CONSISTING ESSENTIALLY OF A MIXTURE OF DIPHENYLAMINE AND CARBON TETRABROMIDE SUPPORTED AS A THIN LAYER, BY EXPOSING SAID FILM TO A SUITABLE DOSE OF RADIANT ENERGY IN THE ULTRAVIOLET, THROUGH SAID NEGATIVE, THEREBY PRODUCING A BLUE-IMAGE SECOND GENERATION POSITIVE PRINT; (2) RINTING A THIRD GENERATION NEGATIVE IMAGE BY EXPOSING A SECOND PHOTOSENSITIVE FILM COMPOSITION TO VISIBLE RADIATION, THROUGH SAID SECOND GENERATION POSITION PRINT; SAID SECOND PHOTOSENSITIVE FILM CONSISTING ESSENTIALLY OF A MIXTURE OF 3-ETHYL-5-((3-ETHYL2 - (3H)BENZOTHIAZOLYLIDENE)ETHYLIDENE) - 2 - (2 QUINOLYLMETHYLENE)-4-THIAZOLIDONE, LEUCO CRYSTAL VIOLET AND CARBON TETRABROMIDE SUPPORTED AS A THIN LAYER, THEREBY PRODUCING A BLACK IMAGE THIRD GENERATION NEGATIVE IMAGE; AND ERATION NEGATIVE IMAGE; AND (3) THERAFTER PRINTING A FOURTH GENERATION POSITIVE BY EXPOSING A PHOTOSENSITIVE COMPOSITION AS DEFINED IN (2) TO A SUITABLE DOSE OF VISIBLE RADIATION THROUGH SAID THIRD GENERATION NEGATIVE.