Automatic Film Processing Method And Apparatus Therefor

Abstract

Selective region development of photographic film is made by relating density of the photographic emulsion with the intensity of an infrared beam directed onto the emulsion and by controlling the intensity as a function of the density. Apparatus for carrying out the method is provided.

Description

The invention hereindescribed was made in the course of or under a contract, or subcontract thereunder, with the United States Government, Department of Defense.

CROSS-REFERENCES

This application is related to each of the following applications, each of which is entitled AUTOMATIC FILM PROCESSING DEVICE AND METHOD: Ser. No. 638,163, filed Mar. 10, 1967; and Ser. No. 657,558, filed Aug. 1, 1967.

BACKGROUND OF THE INVENTION

1. Field of Invention

This invention has to do with a method for processing photographic film and with film-processing apparatus. More specifically, the invention relates to such methods and apparatus which are essentially automatic.

The invention is described and is illustrated hereinbelow with regard to the processing of aerial reconnaissance film. However, it is to be understood that the method and apparatus of this invention are applicable equally to the processing of any type of film.

2. Description of prior art.

One of the prime prerequisites in photography is the faithful recording of detail, which is mainly dependent upon the size and shape of the photographic image, and the density differences which distinguish the image from its surroundings. Major problems are encountered in the recording of this detail due to solar altitude, atmospheric effects (e.g., haze and cloud shadows), terrain types (e.g., beaches and forests) and other factors; this is particularly pronounced in high altitude, wide area, long distance photography where ground detail is contained in a microimage. Large area coverage generally requires great exposure latitude in the film, due to variations in illumination and terrain, the exposure in effect being a compromise between optimum exposure for highlights and shadows or dark areas.

It is desirable to control sensitometric characteristics of individual areas of a film negative without degrading the microimage detail. In an effort to increase the information content of wide area photography, the processing of the photographic film has been improved. By control of film development, the film's ability to record information is increased. Exposure latitude of the film has been extended, while enabling correcting for overexposure or underexposure. Such control can be exercised by change of various parameters of the developer, including: temperature, agitation, development time, and chemical composition.

According to other prior techniques, the agitation or activity of the developing solution over different portions of the film is varied. It is possible with such a system to increase the developing activity in an area of the film where increased activity is desirable.

SUMMARY OF THE INVENTION

The present invention provides a process of selective region development of an exposed and partially developed photographic film by sensing the density of the film by exposure to a radiation beam to which the film is not sensitive, i.e. nonactinic radiation, (typically, infrared radiation); scanning the film directly with a beam of nonactinic radiation which causes heat effects on the film and increases the activity of the developer in the film; and controlling the intensity of the latter beam as a function of the sensed density. A single beam of nonactinic radiation can be generated to measure the density of the film as well as to cause the heating and preferential development. The preferred nonactinic radiation is infrared radiation.

The present invention represents a substantial advance in method and apparatus, which enables variation of the contrast and/or density of the image, and of selected areas of the exposed film, during the course of processing of the latent image. Ordinarily in techniques proposed hitherto, the variables are selected so that the major portions of a film negative, when being developed at a given solution temperature for a given time interval, result in a negative of excellent contrast; a succeeding portion of the film may not, however, due to differences in contrast of the exposed image, respond correspondingly to such temperature and time parameters. Even if a compromise is made, substantial portions of the film may not develop satisfactorily.

DESCRIPTION OF THE DRAWINGS

The construction and operation of the apparatus of the present invention will become apparent from the description which follows, taken in connection with the accompanying drawings, in which:

FIG. 1 is a schematic, diagrammatic view of an embodiment of the invention in which a cold developer is employed;

FIG. 2 is a schematic, diagrammatic view of another embodiment of the invention in which a viscous developer is employed;

FIG. 3 is a schematic, perspective view of the infrared scanning system shown in FIGS. 1 and 2;

FIG. 4 is a block diagram of the electronic components of the infrared scanning system shown in FIGS. 1 and 2;

FIG. 5 is a diagram illustrating the relationship of density (abscissa) and applied infrared energy (ordinate) in various films;

FIG. 6 represents a comparison of graphs of film densities (ordinate) vs. relative log exposure (abscissa) obtained with an aqueous developer for 4 minutes at 20.degree. C. (curve A) and with an ethylene glycol viscous solution of the same developer at temperatures of 20.degree. C. (curve B) and 32.degree. C. (curve C).

FIG. 7 represents a comparison of film densities (ordinate) with the relative log exposure (abscissa) after times of 0 sec. (curve A); 30 sec. (curve B); 60 sec. (curve C); and 120 sec. (curve D).

FIG. 8 is a graph of the relative log exposure (abscissa) versus density (ordinate) at 20.degree. C. (curve A) ; 27.degree. C. (curve B); 32.degree. C. (curve C) and 38.degree. C. (curve D), with the viscous developer of FIG. 6; and

FIG. 9 is a graph of heating temperature (.degree.C.) (abscissa) related to relative film speed (ordinate), using the viscous developer of FIG. 6.

DESCRIPTION OF PREFERRED EMBODIMENTS

In addition to photosensitive media comprising silver halide as the photosensitive component, media comprising other organic or inorganic photosensitive materials can be used herein. These media comprise a photoconductor as the photosensitive component. Preferred photoconductors are metal-containing photoconductors, and particularly preferred are the inorganic materials such as compounds of a metal and a nonmetallic element of group VIA of the periodic table* such as metal oxides, such as zinc oxide, titanium dioxide, antimony trioxide, aluminum oxide, zirconium dioxide, germanium dioxide, indium trioxide, hydrated potassium aluminum silicate (K.sub.2 A1.sub.6 Si.sub.6 O.sub.22 .sup.. 2H.sub.2 O), tin oxide (SnO.sub.2), bismuth oxide (Bi.sub.2 O.sub.3), lead oxide (PbO), beryllium oxide (BeO), silicon dioxide (SiO.sub.2), barium titanate (BaTiO.sub.3), tantalum oxide

Also useful as photoconductors are certain fluorescent materials. Such materials include, for example, compounds such as silver activated zinc sulfide, zinc activated zinc oxide, manganese activated zinc phosphate Zn.sub.3 (PO.sub.4).sub.2, an admixture of copper sulfide, antimony sulfide (SbS) and magnesium oxide (MgO), and cadmium borate.

Suitable organic photoconductors include imidazolidinones, imidazolidinethiones, tetraarylazacyclooctatetraenes, and thiazines, such as 1,3-diphenyl-4,5-bis([-methoxyphenyl)imidazolidinone-2; 4,5-(bis(para-methoxyphenyl)imidazolidinone-2; 4-phenyl-50(para-dimethylaminophenyl)imidazolidinone-2; 4,5-(bis(paramethoxyphenyl)imidazolidenthione-2; 3, 4, 7, 8-tetraphenyl-1, 2, 5, 6-tetraazacyclooctatetraene-2, 3, 6, 8; and methylene blue.

Also useful as photoconductors are heteropolyacids such as phosphotungstic acid, phosphosilicic acid, and phosphomolybdic acid.

Developing agents useful for the media comprising photoconductors are liquid redox systems preferably comprising heavy metal ions such as silver, gold, copper, mercury, and other noble metal ions. British Pat. No. 1,043,250 fully describes suitable developing agents and processes for developing and fixing for use in this invention and is incorporated herein by reference.

Referring now to FIG. 1, exposed film 10 on supply roll 11 is advanced by appropriate motor means (not shown) through tank 12 containing a suitable developer indicated by 13. The developer is maintained at a relatively low temperature, e.g., just above the freezing temperature, in order to minimize activity of the developing agent or agents therein. Film 10 is advanced over a series of idlers 14 and is removed over idler 15. As is obvious to those skilled in the art, various other methods of underdeveloping the film may be used, e.g., use of low-energy developers, shortening the developing time, etc.

Upon removal from tank 12, the emulsion (light-sensitive layer) portion of film 10 will continue to contain developer. Film 10 after having passed over idler 15 is then scanned with a rapidly moving beam of energy to which the film is not sensitive, typically infrared energy, at a station 16. The infrared energy is provided by a suitable source 17, preferably a Xenon lamp or a laser. The IR rays are focused and are directed by an optical system comprising lenses 18 and movable mirror 19, upon film 10. Mirror 19 is mounted on a movable part of galvanometer 20 to scan the beam over the film, as described hereinafter in connection with FIGS. 3 and 4.

As film 10 is scanned with IR energy at station 16, the level of partial development is detected by means of infrared sensor 21. This sensor 21 is positioned on the underside of film 10 and senses the transmissivity, i.e., the inverse of film density. Alternatively, reflectance may be sensed. Sensor 21 is associated with the electronics system depicted in FIG. 4.

A silver halide-type film will still have an appreciable amount of silver halide at station 16, since the film is only partially or predeveloped. Silver halide, the photosensitive material in the undeveloped emulsion on film 10, is a whitish-appearing material having a degree of transparency of about 40-60 percent and a reflectance of about 60-40 percent depending upon the condition and type of the film. Such factors as the degree of wetness, amount of predevelopment and the like, govern the relative transmissivity and reflectance of the film to nonactinic radiation. Metallic silver is a blackish material and hence substantially not transmissive and not reflective. Hence, as the density level of the image on the film increases with increased development, less radiation is transmitted or reflected by any discrete area of the film and less radiation is received by sensor 21. The scanned film is then advanced over idler 22 for further processing, including, in sequence, for example (but not shown) passage through a short stop bath, a fixing bath, a wash section and a drying section, all of which are well known in the art and need not be described in detail.

In FIG. 2, there is shown a modification of the system illustrated in FIG. 1; similar elements have the same reference numerals and are not again described. Instead of the developing bath, a viscous or gel developer is used. With such a developer, a controlled amount of developer can be put on the emulsion of the film and an ample supply of developer constituents is provided. The viscous material or gel provides a substance into which oxidized development products can diffuse; there is reduced developer evaporation, and increased infrared absorption due to the thickness of the viscous or gel developer layer. The film 10 is advanced to viscous or gel developer applicator 50. The applicator may be of conventional form for applying a viscous or gel material to a surface. For example, with viscous material, it may comprise a tank having an adjustable bottom slot and an adjustable doctor blade positioned beside the slot. The gel containing the developer can be applied from a continuous roll supply of gel on a support therefor from which the gel separates on contact with the film. Following application of the developer to film 10, the film is advanced to station 16 as described in connection with FIG. 1. Processing is the same as mentioned with FIG. 1, except that a prewashing can be included before the short stop bath in order to prevent contamination of the short stop bath with emulsifier. Alternatively, the viscous or gel developer can be removed by use of a rubber blade in pressure contact with the film as it advances, thus obviating the need of a prewash.

FIG. 3 illustrates an infrared scanning system wherein infrared source 17 located in a chamber (not shown) provides, in air, an infrared beam 100 which passes through filter 101, lens 102 and thence to mirror 19, from which it is focused upon film 10. The mirror 19 is jointed to the moving element of galvanometer 20 through shaft 103. A relatively large mirror 19 is used to subtend the infrared radiation passed by lens 102. For example, with a .+-. 2.5.degree. rotation of galvanometer shaft 103, a .+-. 5.degree. deflection is given the infrared beam (100).

FIG. 4 illustrates an apparatus automatically adjusting for density, and effecting selective development. Xenon arc lamp 17, shown in block form only, emits a beam of infrared radiation 100 toward mirror 19 scanning across film 10 upon movement of the mirror 19 by the galvanometer 20. The Xenon arc lamp may, for example, have an effective arc area of 0.3 mm. .times.0.3 mm., and an intensity of about 3,000 candles. Even after losses in the lenses, filters, mirror and other auxiliary equipment which may be used, approximately 5 watts of energy can still be applied to the film. Xenon arc lamps have the property that the intensity of the lamp can be modulated electronically, with practically instant response. The infrared radiation can be obtained by other means; lasers are particularly useful providing a sharply collimated and defined beam of high energy. When the laser is used, mirror 19 may be small.

A power supply 200 energizes a drive amplifier 201 controlled by a saw tooth oscillator 202 having a saw tooth wave output to the galvanometer 20, so that the galvanometer 20 will cause the mirror to rotate scanning beam 100 slowly across film 10 and then be returned suddenly to the starting point at one edge thereof. Other means of scanning the beam across the film may, of course, be provided, such as providing a multisided rotating mirror or the like.

A semitransparent mirror 203, that is, a mirror which passes a portion of infrared beam straight through and reflects a portion thereof, is interposed in the path of the beam between galvanometer mirror 19 and film 10. Mirror 203 directs the major portion of the beam 100 onto film 10. After passing through the film, beam 100 strikes photocell 204 which is designed to be specifically sensitive to the wavelength of radiation received. Photocell 204 acts as a sensor of the radiation passing through the film, and develops a signal I.sub.t which is proportional to the radiation transmitted through the film. A second photocell 205 is located in the path of the beam reflected by mirror 203, and from photocell 205 a signal I.sub.o is derived proportional to the output of radiation of lamp 17, which serves as a reference beam. If reflected energy is to be measured, instead of transmitted energy, a reflected beam 100' (FIG.3) is detected by detector 204".

Signals I.sub.o and I.sub.t are compared in a comparator 206 having logarithmic characteristics, that is having a transfer function of

(1) D=log I.sub.o -log I.sub.t..., where D is equal to the density, and I.sub.o and I.sub.t are incident and transmitted radiation, respectively.

The output from the computing device, comparator 206, will appear at a line 207, and is applied to an intensity control adjustment unit 208. The intensity control adjustment unit introduces a distortion into the signal in dependence upon an input, schematically indicated at 209, to compensate for the relative differences in sensitivity to infrared energy of various films. This adjustment may have to be made manually, that is, the input at 209 may be a manual adjustment of parameters of unit 208 which, for example, may include resistance diode networks.

The output from intensity control unit 208, appearing at line 210, is applied to a current modulator 211, which modulates the power applied to lamp 17 from a power source 212, in accordance with the signal appearing at line 210.

A starting circuit, schematically shown at 213, is also provided for Xenon lamp 17.

The transfer function of unit 208 is schematically illustrated in FIG. 5, mathematically:

(2) I=f(D)....

The apparatus of FIG. 4 may be used at station 16 of either of FIGS. 1 or 2.

Operation in accordance with FIG. 1 is as follows. Exposed, unprocessed film 10 is predeveloped in tank 12 (FIG. 1), the temperature of the developer 13 being low enough to minimize the activity of developing agents, for example, of the order of 0.degree. C., allowing only minimal development. Upon removal, the emulsion of the film, that is the light-sensitive layer, will retain all the developer it can hold. Upon scanning across film 10 with a flying spot of infrared energy, beam 100, the infrared beam will heat the emulsion and the developer in inverse relation to the amount of density present in the film. Thus, where there is no density, the sensor 204 will detect a high transmission of infrared, thus controlling through lines 207--unit 208--line 210, the modulator 211 to cause Xenon lamp 17 to provide more energy and thus more heat to the developer. When there is substantial density, sensor 204 will detect a lesser amount of infrared and hence less heat will be applied to that portion of the film. Since the development rate is highly dependent on temperature (as is well known, and as illustrated by the graphs and discussion below), the rate of development can be controlled at incremental regions of the film by heating different portions of the film to different temperatures.

Operation of the apparatus in the system illustrated by FIG. 2 is as follows. The operation is similar to that previously described in connection with FIG. 1, except that unprocessed film 10 is coated with a viscous or gel developer. Development is again allowed to proceed to a minimal amount to provide some density in the film. Heat, again, is applied in inverse relationship to the amount of density present, that is the more density, the less infrared energy is supplied. The signal applied at line 210 is a function not only of the instantaneous density of the film (derived from comparator 206) but also of the processing constants of the film (derived from unit 208). As shown graphically by FIG. 5, the shape and position of the curve will be different for different emulsions used. Manual adjustment at terminal 209 changes this control when the type of film being processed changes.

Comparator 206 can be simple. When silicon photovoltaic cells are used for sensors 204 and 205, and comparator 206 has a high resistance load approaching an open circuit, the output of the silicon cells is practically a logarithmic voltage function of the illumination, so that a simple subtracting network suffices. If the load on the silicon voltaic cells increases, the logarithmic relationship changes and at practically a short circuit across the silicon voltaic cell, current will be proportioned directly to the illumination and to the area of the cell illuminated, so that the logarithmic relationship is established by circuitry within unit 206.

It is not necessary to have sensor 204, sensing the density of the film, exposed to the same source of infrared radiation as that which is utilized to selectively develop the film. A separate source of infrared radiation, or any radiation to which the film is not sensitive so as to avoid fogging, can be provided. The output signal appearing at line 210 can then be applied to a more powerful lamp, or other element instantaneously responsive to the signal at line 210, to cause selective development. Nor is photocell 205 strictly necessary, if the intensity of the radiation source from which the density signal is obtained, is essentially constant. The system illustrated in FIG. 4, however, is a simple closed loop utilizing a minimum of components.

Comparative tests have been made to demonstrate the improvement realized by employing the method and apparatus of the invention.

A 70 mm. aerial negative, showing a section of a Metropolitan area was obtained in which a given exposure had produced a normal density in a sunlit area, but also contained a large area of lower density, caused by cloud shadow coverage. Utilizing conventional developing and printing procedures, the negative was projection printed onto a fine grain, medium contrast, aerial duplication film, type 8430. The projection system comprised a 4.times.5Chromega enlarger equipped with two 100-watt tungsten lamps and 150 mm. lens. With a magnification factor of 4X, an exposure of 28 seconds at f/11 was given. The exposed 8430 film was then processed in the following manner: ---------------------------------------------------------------------------

Developer Coated onto the exposed film utilizing a hand-drawn doctor blade, resulting in a 1/8-inch thickness layer of viscous developer. 6 minutes 20.degree. C. Stop 2% Acetic Acid Solution 10 seconds 20.degree. C. Fix 5 minutes 20.degree. C. Wash 30 minutes 22.degree. C. Air Dried 30 minutes 43.degree. C.

developer water (approx. 50.degree. C.) 500 ml. Elon Developing Agent 2.0 grams Sodium Sulfite, desiccated 90.0 grams Hydroquinone 8.0 grams Sodium Carbonate, monohydrated 52.5 grams Potassium Bromite 5.0 grams Cold water to make 1.0 liter To which was added: 20 grams Sodium Carboxymethocellulose suspended in 100 ml. Methanol thus obtaining the viscous developer used. RAPID FIXING BATH Water (approx. 50.degree. C.) 600 m1. Sodium Thiosulfate (Hypo) 360.0 grams Ammonium Chloride 50.0 grams Sodium Sulfite, desicated 15.0 grams Acetic Acid 28 % 48.0 m1. Boric Acid, crystals 7.5 grams Potassium Alum 15.0 grams Cold water to make 1.0 liter __________________________________________________________________________

Reproduced on film was a satisfactory density record of the cloud shadow area, but information was lost in the sunlit areas due to gross underexposure. Had the initial reproduction been exposed in a manner in which to produce a satisfactory record of the sunlit area, the information contained in the cloud shadow area of the negative would suffer similar consequences and be lost due to gross overexposure. In either procedure, some information contained in the overall scene would be of loss to the viewer.

Additional exposures were made onto type 8430 film in the previously mentioned manner, where an exposure was given to produce a satisfactory record for the cloud shadow area. These films were selectively treated individually with controlled exposures to infrared energy, in the sunlit area only, utilizing an infrared exposure apparatus such as illustrated in FIG. 2.

Each exposed test film was coated individually with the viscous developer, and allowed a one minute initial development period. The area of lower density (sunlit) was treated with varying infrared exposure times. Followed by the continuation of development, resulting in the overall development time of 6 minutes.

Example 1

1 minute initial development

10 seconds on-off infrared exposure

4 minutes 50 seconds continued development

Stop

6 minute total

Example 2

1 minute initial development

60 seconds on-off infrared exposure

4 minutes continued development

Stop

6 minute total.

A satisfactory positive was produced, showing good density and detail in the sunlit area when the film was treated with 30 seconds infrared energy at a distance of 3 inches from the base of an infrared source. The initial positive receiving no infrared exposure lacks both detail and density in the sunlit area.

Sensitometric tests were also conducted. The viscous developer and type 8430 film were used.

Five strips of type 8430 film were exposed to a calibrated step wedge. The exposure given utilized a 100 watt tungsten bulb in conjunction with a 110-volt K & M Tri-Level point source light control unit and a Lectra Decade Interval Timer. At a distance of 30 inches, an exposure time of 2 seconds was given at -3setting on the light control unit.

One strip was then coated with the viscous developer at 20.degree. C. and developed for 6 minutes, thus, producing a gamma of 1.32, relative speed 7.2, Dmin 0.07 and Dmax 2.69. (Curve B shown in FIG. 6)

The remaining strips were then individually processed for a total time of 2 minutes, but during development were selectively treated with varying exposure to infrared energy.

INFRARED EXPOSURE __________________________________________________________________________ Strip - Initial Development IR Exposure Con't. __________________________________________________________________________ Dev. 2 1 minute 10 seconds 50 seconds 3 1 minute 20 seconds 40 seconds 4 1 minute 30 seconds 30 seconds 5 1 minute 40 seconds 20 seconds. __________________________________________________________________________

Results of such tests are set forth in the tabulation below. A definite increase in film speed with increased exposure to infrared energy, without a marked difference in gamma, is shown by Strips -s 1-5. Noteworthy is Strip -5 as compared with Strip -1; 40 seconds of infrared energy development during a total development time of 2 minutes, approximates the result obtained when no infrared exposure was given and a total 6 minute development time was used. ##SPC1##

The method of the present invention, as illustrated by the foregoing comparative examples, is effective for controlling film development rate and, hence, the emulsion speed, in the areas of the negative, by differentially heating the emulsion with infrared energy. The method is superior to conventional processing techniques, in that emulsion speed control during development is possible through controlled amounts of infrared energy. The controlled development makes possible an increase in the amount of information obtainable from aerial films. The method is effective for photographic dodging, which is the photographer's art of improving the quality of reproduction made from poorly exposed film, which generally consists of selectively reducing the amount of light passing through underexposed areas of a negative while allowing the same or more light to penetrate the darker, overexposed portions.

It has been found that viscous or gel developers, referred to in connection with FIG. 2, are advantageous in several respects. For example, there is a lower dissipation of heat by conduction along the surface of the film containing a viscous or gel developer. Less energy is required to raise its temperature and there is no significant cooling due to evaporation. These features are illustrated with a developer wherein ethylene glycol is used in place of a portion of the water normally employed, viz.: ---------------------------------------------------------------------------

Water (125.degree. F.) 100 milliliters Elon 0 .55 gram Sodium sulfite 24 grams Hydroquinone 2 .2 grams Sodium carbonate 14 grams Potassium bromite 1 .2 grams Ethylene glycol balance Total: 250 milliliters __________________________________________________________________________

All materials, except the glycol, were mixed, and the resulting mixture was then added to the ethylene glycol.

The tests mentioned above were repeated, allowing the film strips to soak 60 seconds in the viscous developer at 20.degree. C., after which time they were drained and rapidly heated to an elevated temperature for a 90-second wait time. The film induction time is approximately 60 seconds. The film being removed from the developer at the conclusion of its induction time could continue development with the developer on its surface, thus increasing adjacency effects. By controlling the temperature during this 90-second wait period, the rate of diffusion and thus the development rate was controlled by the temperature as shown in FIG. 8. A satisfactory speed range was obtained. A relative speed vs. temperature curve is given in FIG. 9.

Thus, a standard developer mixed in a solution which is slightly more viscous than it would be when mixed with water, can be used and normal sensitometry obtained which can have a 10X speed change with a 20.degree. C. temperature change. This speed change can be obtained with only that developer remaining on the emulsion after draining.

Film strips processed in the ethylene glycol viscous developer possessed sensitometry comparable to that which is obtained in a comparable aqueous developer. This is shown by FIG. 6. Curve B was lower than Curve A. Increasing the temperature of the film to 32.degree. C. (Curve C), thereby increasing the developer diffusion rate, increased the curve above the curve for the aqueous developer. A 12.degree. C. rise in temperature induced a lateral log E speed shift of 0.68.

Four films were individually soaked in the viscous developer for 60 seconds. They were then removed, drained, and placed on a counter for 0, 30, 60 and 120 seconds before fixing with the same conventional fixing solution. The results are shown in FIG. 7. As indicated, normal sensitometry can be expected from the viscous developer under such conditions.

The viscous developers employed in the present invention may vary widely as to the viscosity. Preferably, the developer should have a viscosity of from about 2,000 centipoises up to several hundred thousand centipoises. For most uses, the flow characteristics of the developer should be of an order which permits efficient flow application onto the photographic film, and retention of the developer on the film surface. As previously indicated, the developer can be provided in the form of a gel which has the physical properties of a continuous film or layer thus rendering it particularly suitable for the present process. The gel film or layer can be applied in predetermined amount to the photographic film from a roll or feed supply composed of the gel on a suitable support from which the gel separates on contact with the photographic film. The thickness of the gel film, concentration of developer and similar considerations are determined by the film requirements and other variables which are obvious to those skilled in the art.

Although the foregoing disclosure is illustrated with infrared as the nonactinic radiation, other forms of radiation can be employed depending on the spectral sensitivity of the film being developed. For example, most silver halide film is sensitive to only blue light but the sensitivity of the film is extended to green and red light by the addition of sensitizers. After exposure, the sensitizers can be removed prior to development, in which case the film is no longer sensitive to either green or red light, both of which may be employed as nonactinic radiation in the present process. A typical reagent to remove the extended sensitivity of such film is pinacryptal green. Methods of desensitizing the films are available in the literature, for example, "Photographic Chemistry," Vol. 2 (Chapters XLII--Desensitization) by P. Glafkides, Fountain Press, London 1960.

Although the invention has been described with respect to the method and apparatus detailed above, it is not intended to be limited to the details so recited, since various modifications may be made without departing in any way from the spirit and scope of the claims appended hereto.

Claims

What is claimed is:

1. In a chemical processing method for selective region development of photographic film having an emulsion with a latent image thereon including the steps of partially developing the latent image in the emulsion and measuring the density of the film in successive regions of the partially developed image, the improvement which comprises directing a beam of nonactinic energy causing heating effect on the film onto successive regions of the film, and controlling the intensity of said beam as a function of said measured density in each region to selectively heat each region of the film, thereby selectively controlling the extent of development in each region of the film.

2. The process of claim 1 wherein said beam of energy is an infrared beam.

3. The process of claim 1 including the steps of

developing a control signal as a function of measured density, and

controlling the intensity of said beam by said control signal.

4. The process of claim 1 wherein transmission density is measured.

5. The process of claim 1 wherein reflection density is measured.

6. The process of claim 2 wherein said infrared beam has a wave length of from about 0.8 to about 1.1 microns.

7. The process of claim 1 wherein said energy beam is provided by a Xenon lamp.

8. The process of claim 1 wherein said energy beam is provided by a laser.

9. The process of claim 1 wherein the intensity of said beam is varied as an inverse function of said control signal.

10. The process of claim 2 wherein the step of directing the beam of infrared energy includes energizing a heat source, focusing a beam of heat radiation and cyclically deflecting the focused beam across the film.

11. The process of claim 10 wherein the cyclical deflection step includes the step of applying the beam to a mirror and cyclically moving the mirror.

12. The method of claim 1 wherein a viscous or gel developer is applied to said emulsion before the film is so scanned.

13. In a chemical processing method for selective region development of photographic film having an emulsion with a latent image thereon including the steps of partially developing the latent image in the emulsion with a developer and measuring the density of the film in the region of the partially developed image by sensing radiation conveyed by the film from a beam of nonactinic energy and scanning the film with a beam of nonactinic radiation which causes heat effects on the film and increases the activity of the developer in the film, the intensity of said latter beam being controlled as a function of the sensed density, the improvement which comprises using a single beam of nonactinic radiation for said density measuring and said scanning.

14. Method as in claim 13 wherein said measuring and said scanning is performed substantially simultaneously.

15. Method as in claim 14 wherein said single beam of nonactinic radiation is an infrared beam.

16. Method as in claim 15 wherein the developer is in the form of a viscous or gel layer on the film.

17. A method as set forth in claim 1 wherein said beam of nonactinic energy is utilized for said density measuring step, and the intensity of said beam is controlled according to the density of the region which is then being simultaneously measured.

18. A method as set forth in claim 13 wherein the intensity of said beam of radiation is controlled simultaneously as the density of the film is being measured.