Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Structurally defined
Reexamination Certificate
2000-12-14
2002-06-04
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Structurally defined
Reexamination Certificate
active
06399288
ABSTRACT:
FIELD OF THE INVENTION
This invention is directed to a method of providing a high contrast color image in color negative films. In particular, it is directed to rapidly processing high contrast, unmasked aerial color negative films. This invention is directed to the photographic industry.
BACKGROUND OF THE INVENTION
Aerial photography is almost as old as photography itself. As soon as people were able to rise above the earth using man made conveyances, the usefulness of imaging various features on the ground was immediately evident. Aerial photography using color photographic films is more recent, but still decades old. The particular characteristics required for such films are high contrast, low minimum density (D
min
) and high resolution (ability to reproduce fine detail) and sharpness. Achieving all of these features at the same time requires specific film formulation and processing conditions especially color development. Not just any conventional color negative film or color developing composition can be used in this manner.
Improved visual contrast may be provided by enhancing film sensitivity in certain regions of the electromagnetic spectrum. For example, U.S. Pat. No. 5,807,666 (Adin et al) describes aerial films that are sensitized in the infrared region to better display tonal separation, provide better haze penetration and improve sensitivity under low visible light conditions.
Specific color negative films designed for aerial photography have been commercialized for many years, for example as KODAK AEROCOLOR Negative Films (Eastman Kodak Company). Such films generally have compositions and structures that are common to multi-color negative films that are processed using conventional Process C-41 processing conditions and chemistry, except that what is known as “color correcting chemistry” is typically omitted from the films. Such chemistry is common for conventional general consumer products where color enhancement and reproduction are essential.
Users of aerial films prefer to obtain images that depict the features on the ground as accurately as possible in what is known as “direct negative interpretation”. In addition, the color negative images should be high in contrast and resolution.
Some conventional high-speed color negative films can be used for aerial photography, achieving the desired high contrast and resolution, if they are exposed to lengthy color development. However, there is a need in the photographic industry for a means to achieve high contrast and sharp color images in shorter times without having to make significant and costly changes to processing equipment and chemistry.
SUMMARY OF THE INVENTION
The present invention provides a first method of providing a color negative image having a contrast of at least 0.83, a D
min
less than 0.45, an rms granularity of less than 17, a modulation transfer function greater than 39 DMT, a resolving power greater than 80 at 1000:1 high contrast test target and a resolving power greater than 63 at 1.6:1 low contrast test target, the method comprising:
A) contacting an “unmasked” color negative silver halide photographic film with a color developing composition having a pH of from about 10.2 to about 10.6 and comprising at least 0.006 mol/l of a color developing agent,
the contacting being carried out for less than 180 seconds at a temperature of from about 40 to about 42° C.
This invention also provides a second method of providing a color negative image having a contrast of at least 0.8, a D
min
less than 0.41, an rms granularity of less than 16, a modulation transfer function greater than 39 DMT, a resolving power greater than 100 at 1000:1 high contrast test target and a resolving power greater than 63 at 1.6:1 low contrast test target, the method comprising:
A) contacting an “unmasked” color negative silver halide photographic film with a color developing composition having a pH of from about 9.8 to about 10.2 and comprising at least 0.01 mol/l of a color developing agent,
the contacting being carried out for at least 240 seconds at a temperature of from about 37 to about 39° C.
We have found that the first method of the present invention provides a high contrast color image with low minimum density, very high resolution and low granularity. This type of color image is obtained from an unmasked color negative silver halide photographic film that is color developed for less than 180 seconds at from about 40 to about 42° C. with a color developing composition having a pH of from about 10.2 to about 10.6 and comprising at least 0.006 mol/l of a color developing agent. This invention is particularly useful for providing high contrast, high resolution color images from medium to high altitude aerial photography.
The second method of the present invention is similar to the first method, but it more useful for providing the same high quality images using slightly different color development conditions, namely for at least 240 seconds (a so-called “push” process) at from about 37 to about 39° C. using a color developing composition having a pH of from about 9.8 to about 12.1 and comprising at least 0.01 mol/l of a color developing agent.
DETAILED DESCRIPTION OF THE INVENTION
The method of this invention is useful for providing a high contrast color negative image in a single- or multi-color negative photographic silver halide film. Such films generally have an aerial film speed (EAFS or ISO A equivalent) of at least 64, and preferably of at least 100. The speed or sensitivity of color negative films is inversely proportional to the exposure required to enable the attainment of a specified density above fog after processing. This film speed should not be confused with conventional film speeds designed for roll and sheet films employed in consumer photography. Different film speed parameters are used to relate aerial scene characteristics to practical exposure recommendations. Aerial film speeds can be determined as described in KODAK Aerial Exposure Computer, KODAK Publication AS-10 (February 1994).
The color negative films useful in the practice of this invention generally have an exposure latitude of at least 2 log E, and preferably of at least 2.3 log E. As is well understood in the art, exposure latitude defines the useful range of exposure conditions that may be recorded on a light sensitive element.
The photographic films used in the practice of this invention are preferably multilayer color elements having three color records. Such color records (or dye image-forming units) are sensitive to different regions of the visible spectrum (for example the primary regions). Each color record can include one or more silver halide emulsion layers sensitive to the same given region of the spectrum. The layers can be arranged in any of the various orders known in the art. The films can also contain other conventional layers such as filter layers, interlayers, subbing layers, overcoats and others readily apparent to one skilled in the art. A magnetic backing layer can be used as well as conventional transparent film supports that are also well known in the art (such as cellulose acetate and conventional film-forming polyesters).
Considerable details of film structure and composition are outlined in
Research Disclosure
publication 38957, published September 1996, and in the hundreds of publications noted therein.
Research Disclosure
is a publication of Kenneth Mason Publications, Ltd. Dudley House, 12 North Street, Emsworth, Hampshire PO10 7DQ English (also from Emsworth Design Inc, 121 West 19th Street, New York, 10011). Included within such teaching are the various useful classes of cyan, magenta and yellow dye forming couplers that can be used in the red, green and blue color records of the color negative films. Particular classes of dye forming couplers useful in the practice of this invention are the substituted phenol and &agr;-naphthol cyan dye forming couplers, the aryl-pyrazolinone and pyrazolotriazole magenta dye forming couplers, and the &bgr;-ketocarboxyamide (specifically the benzoylacetanilides and p
Kennelly Daniel T.
Larkin Thomas P.
Leith Charles F.
Mango Steven A.
Eastman Kodak Company
Le Hoa Van
Tucker J. Lanny
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