Novel xanthene compounds and photographic products and processes employing the same

In one embodiment, the present invention is concerned with novel xanthene compounds of the formula ##STR1## wherein each R.sup.1 the same or different is hydrogen or alkyl, each R.sup.2 the same or different is alkyl or phenyl, R.sup.3 is phenyl or alkyl, Y is an electron-withdrawing group and A is an anion. In another embodiment, the present invention is concerned with photographic products and processes employing these xanthene compounds.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to novel xanthene compounds and to their use, e.g., 
as light-screening dyes in photographic products and processes. 
2. Description of the Prior Art 
It is well known that photographic film, and especially multicolor films, 
may and generally do vary from lot to lot, notwithstanding efforts to 
"repeat" previous films. Manufacturers of multicolor photographic films 
have developed a number of procedures to minimize the effects upon the 
final multicolor image of unavoidable variations in the manufacturing 
operations. These variations are reflected primarily in shifts in color 
balance as reflected in mismatching of the D log E curves of the 
individual red, green and blue exposures. Equipment used to coat 
multicolor films is highly precise but variations between intended 
coverage of silver halide and/or the dye image-forming materials do occur. 
Repeat batches of silver halide emulsions may, and usually do, vary in 
their photographic response. Individual layers may be dried to slightly 
different degrees. Films are stored for a period of time after coating to 
allow the films to "age", so that changes in sensitometry following 
coating have an opportunity to reach a plateau prior to sale. If the film 
is designed to be developed by a photofinisher or in a darkroom, 
processing of the exposed multicolor film is controlled within very narrow 
limits, typically within plus or minus a half degree of a prescribed 
temperature, in order to minimize sensitometric variations from film to 
film. Where the multicolor film is of the negative type, an opportunity to 
adjust the sensitometry occurs in printing the desired final positive 
image, during which operation the printing exposure may be appropriately 
color filtered. 
The basic sources of sensitometric variations noted above exist also in 
multicolor diffusion transfer films, with the added complication that once 
the film is shipped, the sensitometric properties are essentially fixed. 
The opportunity for adjustment provided in darkroom processing, 
practically speaking, is unavailable for users of self-developing films. 
While professional and advanced amateur photographers may be skillful 
enough to utilize color correction filters to at least partially 
"rebalance" the color balance, ordinary users of the film would only be 
confused by such additional operations. 
It is well known to use light-screening dyes in photographic elements. Such 
a dye may be incorporated as a filter dye in a light-sensitive emulsion 
layer(s) or in a layer coated over one or more light-sensitive emulsion 
layers or between two differently color-sensitized emulsion layers to 
modify the light record in the emulsion layer or to control the spectral 
composition of light falling on the underlying light-sensitive layer, or 
it may be incorporated as an anti-halation dye in a non-light-sensitive 
layer positioned on either side of a support carrying the light-sensitive 
layer(s). 
The dyes employed for these purposes, in addition to having the requisite 
spectral absorption characteristics for their intended use, should be 
photochemically inert, that is, they should not have any adverse effect on 
the properties of the light-sensitive emulsion layer(s), and also, they 
should be capable of being decolorized or removed during photographic 
processing so as not to leave stain in the processed photographic element. 
In photographic processes where the dye is removed by being dissolved in a 
processing solution, it is usually preferred that the dye also decolorize 
in order to avoid contamination of the processing solution and to prevent 
staining from residual dye in the processed light-sensitive element. 
Though various classes of dyes have been proposed for use in antihalation 
and color correction filter layers, the dyes heretofore employed have not 
been altogether satisfactory. Some of the dyes tend to reduce sensitivity, 
fog or exert other adverse effect on the light-sensitive material. 
However, the major drawback of previously employed dyes is their tendency 
to cause stain due to incomplete decolorization or reversal of some of the 
decolorized form to the original colored form. For example, some classes 
of dyes rely on the presence of a reagent, such as, a sulfite for 
"bleaching", i.e., decolorization and unless the dyes are removed from the 
light-sensitive material during or after processing, their color may 
reappear in time. 
Among the classes of light-screening dyes used previously are the 
triarylmethanes and xanthenes. For example, U.S. Pat Nos. 1,879,537; 
1,994,876; 2,350,090 and 3,005,711 disclose the use of fuchsone-type dyes 
in antihalation layers, and U.S. Pat. Nos. 3,406,069 and 3,615,548 are 
concerned with the metal chelates of fuchsone dyes as antihalation dyes. 
These and other types of triarylmethane dyes suffer from one or more of 
the drawbacks discussed above, and in particular, prior dyes of this type 
have been difficult to keep decolorized at the pH's normally encountered 
during processing subsequent to "bleaching" and in the final product. 
Xanthenes have been employed in antihalation layers that are removed 
during photographic processing. For example, U.S. Pat. Nos. 2,182,794; 
2,203,767 and 2,203,768 disclose the use of rhodamine dyes in certain 
antihalation layers that are removed during processing in an acid bath or 
a plain water rinse bath depending upon the solubility characteristics of 
the particular layer. 
Copending U.S. Patent Application Ser. No. 106,520 of James W. Foley filed 
concurrently herewith is concerned with colored triarylmethane compounds 
possessing in their triaryl structure a 
4'-oxo-1'-naphthylidene/phenylidene moiety, a naphthyl/phenyl moiety and a 
phenyl moiety substituted in the position ortho to the central carbon atom 
with a group that undergoes an irreversible cleavage reaction in base to 
provide a moiety that adds to the central carbon atom to form a new 
ring-closed compound which is colorless. As disclosed and claimed therein, 
these compounds are useful as photographic light-screening dyes which 
offer advantages over prior light-screening dyes because of their ability 
to decolorize completely and irreversibly to a substantially inert 
colorless product. 
The present invention is concerned with another class of compounds, namely, 
xanthene compounds which also find utility as photographic light-screening 
dyes and which also are free from the deficiencies associated with the 
dyes previously used for this purpose. The subject dyes, which will be 
defined with greater particularity hereinafter, are efficient absorbers of 
radiation within a predetermined range in the visible range of 400 to 700 
nm, may be incorporated in gelatin or other processing 
composition-permeable colloidal binding agents and are decolorized at an 
alkaline pH to yield a colorless product. Because of their ability to 
decolorize completely and irreversibly in base without requiring an 
additional reagent, such as, a sulfite for the "bleaching" reaction and 
because the new colorless product produced upon irreversible cleavage 
remains colorless in aqueous solution over a pH range of about 4 to 14, 
the cleavage product normally may be retained in the photographic 
light-sensitive element without the possibility of color reappearing in 
time. Besides being non-staining, the compounds usually are substantially 
inert with respect to the light-sensitive material and thus, may be 
positioned in a layer adjacent to a silver halide emulsion layer or 
directly incorporated into an emulsion layer without having any adverse 
effect on the properties of the emulsion. 
Xanthenes of the structure 
##STR2## 
wherein R is H or --COCH.sub.3 are disclosed in Beilstein's Handbuch der 
Organischen Chemie, Vol. 27, p. 534. These compounds are synthesized by 
condensing m-diethylaminophenol with saccharin at a temperature of 
165.degree. C. to give the compound wherein R is H, which compound is then 
heated to boiling with acetic acid anhydride to yield the N-acylated 
derivative. As reported therein, solutions of the N-acetyl compound unlike 
solutions of the N-unsubstituted compound (R.dbd.H) are not decolorized by 
boiling, and the acetyl group splits off only after prolonged boiling with 
alcoholic sodium hydroxide. Further to the N-unsubstituted compound, it 
has been found that this compound is colorless at an alkaline pH, faintly 
colored at neutrality and becomes more intensely colored as the pH is 
reduced to pH 4. 
SUMMARY OF THE INVENTION 
It is therefore the primary object of the present invention to provide 
novel xanthene compounds. 
It is another object of the present invention to provide xanthene compounds 
useful in photographic products and processes. 
It is a further object of the present invention to provide photographic 
products and processes employing said compounds. 
Other objects of this invention will in part be obvious and will in part 
appear hereinafter. 
This invention accordingly comprises the process involving the several 
steps and the relation and order of one or more of such steps with respect 
to each of the others and the products and compositions possessing the 
features, properties and the relation of elements which are exemplified in 
the following detailed disclosure and the scope of the application of 
which will be indicated in the claims. 
According to the present invention, novel xanthene compounds are provided 
which possess an N-alkyl/aryl group in each of the 3 and 6 positions and a 
substituted phenyl moiety in the 9 position which moiety has the formula 
##STR3## 
wherein R.sup.3 is alkyl or phenyl and Y is an electron-withdrawing group. 
In another embodiment, photographic products and processes are provided 
which employ the above-denoted xanthene compounds, which compounds are 
irreversibly decolorized by forming a new ring-closed compound when 
contacted with an alkaline photographic processing composition. 
For a fuller understanding of the nature and objects of the present 
invention, reference should be had to the following detailed description 
taken in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION 
Specifically, the compounds employed in accordance with the present 
invention may be represented by the formula 
##STR4## 
wherein each R.sup.1 the same or different is hydrogen or alkyl, each 
R.sup.2 the same or different is alkyl or phenyl, R.sup.3 is alkyl or 
phenyl, Y is an electron-withdrawing group and A is an anion. By 
"electron-withdrawing group" is meant a group having a positive sigma 
value as defined by Hammett's Equation. 
Typically said R.sup.1 and R.sup.2 groups, when alkyl, contain 1 to 4 
carbon atoms, and R.sup.3 is alkyl containing 1 to 4 carbon atoms. Usually 
said R.sup.1 groups are the same, and said R.sup.2 groups are the same. 
The electron-withdrawing group, Y, preferably has a positive sigma value 
(.sigma..sup.-) greater than 0.6. Preferred electron-withdrawing groups 
include nitro; cyano; --SO.sub.2 CH.sub.3 ; 
##STR5## 
COCH.sub.3 ; and --SO.sub.2 N(CH.sub.2 Ph).sub.2. The sigma value for 
these and other groups, such as, --CHO; --COOH, --COOC.sub.2 H.sub.5 and 
--CONH.sub.2 have been reported by Eugen Muller, Methoden Der Organischen 
Chemie, Georg Thieme Verlag, Stuttgart, 1970, p. 78 in terms of 
.sigma..sup.- values based on the ionization of p-substituted phenols. 
The anion associated with the subject xanthene compounds, i.e., A in 
formula I above may be any of the simple anions, for example, tosylate, 
sulfate, nitrate, perchlorate, acetate, oxalate, methanesulfonate or 
halide, such as, chloride or bromide. 
It should be understood that other resonance forms of the subject compounds 
are intended to be encompassed by Formula I. 
As noted above, the subject compounds are initially colored, i.e., capable 
of absorbing visible radiation, and at an alkaline pH, are converted to a 
colorless product by undergoing an irreversible cleavage reaction with 
base. The colorless product formed is a new compound which is different 
from and non-reversible to the colored compound by a change in pH. In 
particular, it is the 
##STR6## 
group substituted on the phenyl moiety that undergoes the irreversible 
cleavage reaction in alkaline solution that is complete within a 
predetermined time at a predetermined alkaline pH to give the new 
colorless compound, namely, the cyclic carboxamide, as illustrated by the 
following wherein A is Br.sup..crclbar. and R.sup.3 is methyl. 
##STR7## 
It will be appreciated that the by-products formed upon cleavage of the 
R.sup.3 group also are colorless. Because the said cleavage reaction 
proceeds at a faster rate at higher pH's, the subject compounds are 
particularly suitable for use in photographic processes where the pH is 
maintained above about 10 at least for the time necessary for 
decolorization to the corresponding ring-closed product. 
The xanthene dyes of the present invention may be prepared, for example, 
(a) by reacting a compound of the formula 
##STR8## 
with a phenyl- or alkylamine to give the compound of the formula 
##STR9## 
wherein R.sup.3 is alkyl or phenyl; 
(b) treating the last-named compound with zinc in glacial acetic acid to 
give the compound of the formula 
##STR10## 
(c) reacting the last-named compound with the selected acylating agent, for 
example, ClCO.sub.2 (CH.sub.2).sub.2 Y to give the leuco dye precursor of 
the formula 
##STR11## 
(d) oxidizing the leuco dye precursor with, for example, iodine or with, 
for example, o-chloranil and removing the dye product from its complex 
with o-chloranil with an acid to give the dye. 
It will be appreciated that R.sup.1, R.sup.2 and Y in the foregoing 
reaction sequence have the same meaning as given in Formula I above. 
The acylating agent may be prepared in a known manner by reacting the 
selected HO(CH.sub.2).sub.2 Y with phosgene to give the corresponding 
ClCO.sub.2 (CH.sub.2).sub.2 Y. 
The rhodamines used as starting materials in synthesizing the subject dyes 
may be prepared in a conventional manner, for example, as described in K. 
Venkataraman, The Chemistry of Synthetic Dyes, Vol. II, pp. 750-54, 
Academic Press Inc., N.Y. (1952). 
The following Example is given to further illustrate the present invention 
and is not intended to limit the scope thereof. 
EXAMPLE 
Preparation of the compound having the formula 
##STR12## 
(a) To a solution of 7.5 g of the ethyl ester of Rhodamine B dissolved in 
50 ml water was added 50 ml of 40% methylamine in water. The resulting 
solution was stirred for 4 hours during which time a pink solid 
precipitated and the deep magenta color disappeared. Another 50 ml of 
water was added to the flask and the solution was filtered. The solid was 
washed well with water and placed in a flask with 200 ml of acetone and 
heated to reflux until complete solution resulted. The solution was cooled 
and the white crystals were filtered. (yield 5.7 g) The mother liquor was 
evaporated to approximately 50 ml and allowed to stand. A second crop of 
0.8 of solid was collected to give a total of 6.5 g of the compound. 
##STR13## 
(b) One gram of the compound of step (a) was dissolved in glacial acetic 
acid under nitrogen. To this solution was added two spatulas of zinc, and 
then this reaction mixture was stirred well while heating on a steam bath. 
The magenta color disappeared with time and 25 ml of ether was added to 
the cooled solution. The zinc was filtered and washed with ether. A white 
solid then crystallized from the filtrate. More ether was added and 
filtered. A fluffy solid was filtered and vacuum dried to give 0.8 g of 
the compound. 
##STR14## 
(c) A solution of 0.65 g of the compound of step (b) dissolved in 20 ml of 
tetrahydrofuran under nitrogen was cooled to -65.degree. C. A solution of 
1.6 M butyllithium in hexane (0.88 ml) was added dropwise and the mixture 
allowed to stir for one hour at -65.degree. C. To this was added 0.53 g of 
ClCO.sub.2 (CH.sub.2).sub.2 SO.sub.2 CH.sub.3 and the reaction mixture was 
stirred overnight. TLC on silica gel with 1/9 petroleum ether/ether showed 
mainly starting material. More of the chloroformate was added. Then the 
mixture was stirred but no further reaction occurred. The reaction mixture 
was poured into water and the precipitate removed by filtration. 
Preparative TLC on a sample of the light purple precipitate gave the leuco 
dye precursor 
##STR15## 
(d) The leuco dye precursor (50 mg) was dissolved in 10 ml of ethanol and 
air was bubbled through the light pink solution. Iodine (10 mg) was added, 
and a deep magenta developed. The solution was stirred for 2 hours. (TLC 
on silica gel with ether showed no starting material remaining. TLC on 
silica gel with 10% methanol/methylene chloride showed traces of other 
spots.) The reaction mixture was evaporated to dryness leaving the title 
compound as a purple solid. 
The lactams of 2-[3,6-bis-diethylamino-9-anilinoxanthyl] benzoic acid and 
2-[9-amino-3,6-bis-diethylaminoxanthyl] benzoic acid are disclosed in 
Beilstein's Handbuch der Organischen Chemie, Vol. 27, p. 431. 
A sample of the dye prepared in the above Example was incorporated into the 
image-receiving layer 3 of an image-receiving component comprising the 
following layers. 
A transparent 4 mil polyethylene terephthalate film base coated with, in 
succession: 
1. as a polymeric acid layer, a mixture of about 9 parts of a partial butyl 
ester of polyethylene/maleic anhydride copolymer and 1 part of polyvinyl 
butyral coated at a coverage of about 2,500 mgs./ft..sup.2 ; 
2. a timing layer containing a 14:1 ratio of a 60-30-4-6 tetrapolymer of 
butylacrylate, diacetone acrylamide, styrene and methacrylic acid and 
polyvinyl alcohol at a coverage of 500 mgs./ft..sup.2 ; 
3. a graft copolymer of 4-vinylpyridine and 
vinylbenzyltrimethylammoniumchloride grafted on hydroxyethyl cellulose in 
a weight ratio of 2.2/1/2.2, respectively, coated at a coverage of 300 
mgs./ft..sup.2 to provide an image-receiving layer. 
The .lambda.max of the dye as measured in the above-described 
image-receiving component was 568. When an aqueous 1 N sodium hydroxide 
solution was applied to the image-receiving layer of said image-receiving 
component, the dye was rendered colorless and remained colorless for at 
least 96 hours. 
As a comparison, a dye compound of the formula 
##STR16## 
was incorporated into the image-receiving layer of an image-receiving 
element identical to that described above, the only difference being the 
use of ethanol as solvent. The .lambda.max of compound A as measured in 
said image-receiving element was 567. When the image-receiving layer was 
treated with an aqueous solution approximately 1 N in sodium hydroxide, 
the dye was rendered colorless, but after about 15 minutes, a magenta 
color reappeared. 
The compound of the above Example and Compound A undergo an irreversible 
cleavage reaction in aqueous alkaline solution at ambient temperature to 
give the new ring-closed cleavage products of the formulae 
##STR17## 
As apparent from the above comparison, the ring-closed cleavage product of 
the compound of the Example remained colorless in the image-receiving 
element even after the environmental pH had been reduced below about pH 
5.5 by said polymeric acid layer whereas the ring-closed cleavage product 
of Compound A became colored as the pH dropped. 
In a further comparison, the approximate pH at which the above-denoted 
cleavage products became colored as the pH was reduced from alkaline to 
acid values was determined using pH buffers. It was found that the 
cleavage product of the subject dye remained colorless down to about pH 4, 
while the cleavage product of Compound A was faintly colored at pH 7 and 
became more intensely colored as the pH was reduced to about pH 4. 
Though the alkyl/phenyl substituent on the N atom of the 
##STR18## 
group is not essential to give a cleavage product that remains colorless 
as the pH is reduced, it is desirable to so substitute said N atom to 
increase the epsilon of the uncleaved dye to give a more highly colored 
compound. 
Compound A was prepared by dissolving 477.6 mg (1.0 mM) of the compound. 
##STR19## 
in 7.5 ml dry pyridine and then adding 205.3 mg (1.1 mM) of ClCO.sub.2 
(CH.sub.2).sub.2 SO.sub.2 CH.sub.3. The resulting reaction mixture was 
stirred at room temperature for about 16 hours at which time TLC showed 
that the reaction was about 65% complete. Another 200 mg of the 
chloroformate was added and the mixture stirred for another 6 hours at 
room temperature. (After 24 hours TLC showed the reaction substantially 
complete.) After additional stirring, the mixture was poured into 50 ml 
water, stirred for about 30 minutes and transferred to a separatory 
funnel. The mixture was extracted with methylene chloride (3.times.50 ml). 
The combined methylene chloride extracts were washed with water 
(2.times.50 ml), saturated sodium chloride (1.times.50 ml) and dried over 
sodium sulfate. The solvent was removed in vacuo leaving about 750 mg of 
residue. About 200 mg of the residue was dissolved in about 4 ml methylene 
chloride and using preparative TLC techniques, the product was separated 
and washed with acetone/methylene chloride. The acetone was removed in 
vacuo, and the product transferred to a 50 ml flask with methylene 
chloride. The methylene chloride was evaporated leaving 153 mg of Compound 
A. 
As noted previously, the dyes of the present invention have the ability to 
decolorize completely and irreversibly in base by undergoing an 
irreversible cleavage reaction with a predetermined time at a 
predetermined pH to give a new colorless compound which remains colorless 
at the pH's normally encountered during processing subsequent to 
"bleaching" so that the new compound may be retained in a photographic 
film unit, e.g., a photosensitive element without the possibility of color 
reappearing in time. Typically, dyes may be selected for use as 
antihalation dyes, e.g., in a non-light-sensitive layer positioned 
intermediate a photosensitive silver halide emulsion layer and the 
support. Also, dyes may be selected for use as color correction filter 
dyes where absorption of light within a particular wavelength range during 
exposure is desirable for achieving appropriate color balance. 
Illustrative film units in which the dyes of the present invention may be 
advantageously used as antihalation dyes are described, for example, in 
British Pat. No. 1,482,156. These film units comprise, in the order in 
which incident light passes therethrough, an additive multicolor screen, a 
photosensitive silver halide emulsion layer, an antihalation layer in 
which the selected compound may be disposed, and preferably, an 
image-receiving layer. As described therein, exposure of the silver halide 
layer is accomplished through the screen which possesses optical filter 
elements selectively transmitting predetermined portions of incident 
radiation, e.g., red, green and blue light, to the underlying 
photosensitive silver halide layer. Upon photographic processing with an 
aqueous alkaline processing composition, soluble silver complex is 
transferred by diffusion and deposited in a superposed image-receiving 
layer as a function of the degree of exposure of silver halide behind each 
filter element. The silver image thus formed may then serve to modulate 
the quantity of light passing through the filter elements in the reverse 
direction during projection through a transparent support. 
In a preferred embodiment, the image-receiving layer is intermediate the 
photosensitive silver halide emulsion layer and the additive multicolor 
screen and remains in position as part of an integral film unit prior to, 
during and after formation of the image. The antihalation dye is disposed 
in a processing composition permeable layer adjacent to the photosensitive 
layer on the side opposite the screen and serves to prevent the reflection 
or back-scattering of incident light which has passed through the 
photosensitive layer thereby eliminating the exposure of silver halide 
grains in the photosensitive layer other than those within the intended 
photoexposure path. 
As noted above, the dyes of the present invention also are useful as color 
correction filter dyes in photographic film units comprising multilayered, 
multicolor photosensitive elements employing a blue-, a green-, and a 
red-sensitive silver halide layer, and particularly in integral 
negative-positive diffusion transfer film units wherein the 
image-receiving layer carrying the color transfer image is not separated 
from the developed photosensitive layers after processing but both 
components are retained together as a permanent laminate. Included as part 
of the laminate is a layer of light-reflecting material, preferably 
titanium dioxide, positioned between the image-carrying layer and the 
developed photosensitive layer(s). The light-reflecting layer separating 
the image-carrying and photosensitive components provides a white 
background for the transfer image and masks the developed photosensitive 
layer(s). In addition to these layers, the laminate usually includes 
dimensionally stable outer layers or supports, at least one of which is 
transparent so that the resulting transfer image may be viewed by 
reflection against the background provided by the light-reflecting layer. 
Illustrative of patents describing such film units are U.S. Pat. No. 
2,983,606 issued Mar. 9, 1961 to Howard G. Rogers, U.S. Pat. Nos. 
3,415,644, 3,415,645 and 3,415,646 issued Dec. 10, 1968 to Edwin H. Land, 
U.S. Pat. Nos. 3,594,164 and 3,594,165 issued July 20, 1971 to Howard G. 
Rogers, and U.S. Pat. No. 3,647,437 issued Mar. 7, 1972 to Edwin H. Land. 
U.S. Patent application Ser. No. 537,124 of Edwin H. Land, now abandoned, 
is concerned with multicolor diffusion transfer film units, wherein a 
layer of a dye, preferably a dye bleachable by the processing composition, 
is so positioned that photoexposure is effected therethrough, whereby said 
dye layer is effective as a color correction filter. For convenience, the 
specification of this application is specifically incorporated herein. 
Whether used as antihalation dyes, color correction filter dyes or in other 
conventional photographic light-screening applications, the dyes of the 
present invention when disposed in a processing composition-permeable 
layer are completely and irreversibly decolorized by contacting with an 
aqueous alkaline processing composition for the time necessary for 
converting the colored dye compound to the new colorless ring-closed 
compound. The time required for decolorization, i.e., for conversion of 
the colored compound to the colorless product via said irreversible 
cleavage reaction may be measured at any given alkaline pH, and for a 
selected decolorization time, the pH of the processing composition 
contacted with and remaining in contact with the colored filter dye should 
be at least as high as that predetermined to give the selected 
decolorization time. In terms of T1/2, the preferred compounds have a 
half-life (T1/2) in approximately 1 N NaOH of about 30 seconds or less. By 
T1/2 is meant the time measured for one-half of said colored dye to 
decolorize. 
The dyes of the present invention may be incorporated into the appropriate 
layer of the photographic film unit using any of the techniques known in 
the art. For instance, the selected compound can be dissolved in the 
appropriate solvent and then dispersed, in the presence of a wetting agent 
if desired, in a coating solution containing a hydrophilic colloid binder, 
e.g., gelatin, and the resulting coating solution applied as the desired 
layer, for example, coated on a transparent support to provide an 
antihalation layer, or coated over the outermost photosensitive layer of a 
multilayered, multicolor photosensitive element to provide a color 
correction filter layer through which photoexposure is made. The 
concentration of compound in the layer will vary depending upon the 
product in which the filter layer is to be used and may be readily 
determined empirically to provide the optical density necessary for the 
specific use. It will be appreciated that the dyes of the present 
invention may be used in combination with each other and also may be used 
in combination with other classes of dyes previously employed in 
antihalation, color correction and other filter layers. 
FIG. 1 of the accompanying drawing, which illustrates one embodiment of the 
present invention, is an enlarged cross-sectional view of an integral 
diffusion transfer film unit comprising a transparent film base or support 
1 carrying on one surface, in order, additive multicolor screen 3 
comprising a plurality of primary red color filter elements, a plurality 
of primary green color filter elements and a plurality of blue color 
filter elements arranged in a geometrically repetitive distribution in 
side-by-side relationship in substantially a single plane, 
photoinsensitive layer 5 carrying silver precipitating nuclei, 
photosensitive layer 7 containing silver halide crystals and antihalation 
layer 9 containing one or more light-screening dyes of the present 
invention. 
As discussed in aforementioned British Pat. No. 1,482,156, the degree of 
light absorption of the antihalation layer in such film units can vary 
over a relatively wide range, but usually, the antihalation layer 
possesses a transmission density range from about 0.4 to 1.4. Preferably, 
the transmission density is greater than 0.6 so that in the event a 
plurality of film units is employed in a stacked relationship during 
photoexposure, the antihalation layer will have sufficient density, i.e., 
light-absorbing capacity to substantially prevent reflectance as well as 
prevent exposure of underlying film units. 
In determining the appropriate light-absorbing capacity for cyan, magenta 
and yellow for color correction purposes, "color compensating" filters as 
conventionally used in front of the camera lens may be employed in the 
usual manner as a convenient method of approximating the type and quantity 
of filtration which it would be desirable to provide. A layer containing 
the appropriate color correction dye(s) in a corresponding density may 
then be provided as a layer through which photoexposure is to be made. 
Multicolor diffusion transfer images may be obtained using a variety of 
arrangements of the image-receiving layer and the silver halide emulsions. 
Thus, these layers may be carried by a common support brought into 
superposition after photoexposure. A particularly advantageous film 
structure is shown in U.S. Pat. No. 3,415,644 wherein the requisite layers 
are in superposed relationship prior to and during photoexposure, and 
these layers are maintained in superposed relationship as a permanent 
laminate after processing and image formation. Such film units typically 
contain an outer transparent layer or support through which photoexposure 
is effected and the final multicolor image viewed, and another outer layer 
or support carrying at least the photosensitive layers, the latter support 
being opaque. While these supports or sheet-like elements may simply be 
held in superposed relationship, e.g., by a binding tape around the edges, 
in the preferred embodiment these elements are laminated together prior to 
photoexposure. This prelamination provides a number of benefits, both 
during manufacture and in photoexposure. Following exposure, the elements 
are delaminated by the distribution of a fluid processing composition 
which, upon solidification, bonds the elements together to form the 
desired permanent laminate. Procedures for forming such prelaminated film 
units wherein the two elements are temporarily laminated together prior to 
exposure are described, for example, in U.S. Pat. No. 3,625,231 to Albert 
J. Bachelder and Frederick J. Binda, and U.S. Pat. No. 3,652,282 to Edwin 
H. Land, both issued Mar. 28, 1972 and in U.S. Pat. No. 3,793,023 issued 
to Edwin H. Land on Feb. 19, 1974. 
Further description of this embodiment of the present invention may be 
facilitated by reference to FIG. 2 of the accompanying drawing which 
illustrates a diffusion transfer film unit adapted to provide integral 
negative-positive reflection prints and employing dye developers as the 
image dyes. 
FIG. 2 illustrates a diffusion transfer film unit comprising a 
photosensitive element or component 2, a rupturable container 30, and an 
image-receiving element or component 4. The photosensitive element 2 
comprises an opaque support 10 carrying, in turn, a cyan dye developer 
layer 12, a red-sensitive silver halide emulsion layer 14, an interlayer 
16, a magenta dye developer layer 18, a green-sensitive silver halide 
emulsion layer 20, an interlayer 22, a yellow dye developer layer 24, a 
blue-sensitive silver halide emulsion layer 26, and an auxiliary layer 28. 
The positive or image-receiving element 4 comprises a transparent support 
40 carrying, in turn, a polymeric acid layer 42, a timing layer 44 and an 
image-receiving layer 46 having dispersed therein a bleachable, 
light-screening dye of this invention as a color correction filter dye. 
The two elements are held in superposed, registered relationship, e.g., by 
a binding tape (not shown), so that photoexposure of the silver halide 
emulsion layers is effected through image-receiving layer 46 containing 
the bleachable dye. The rupturable container 30 contains a processing 
composition and is so positioned that, upon rupture the processing 
composition is distributed between the superposed elements 2 and 4. By 
including in the processing composition a light-reflecting pigment, 
preferably titanium dioxide, a light-reflecting layer may be provided 
against which the transfer image formed in the image-receiving layer 46 
may be viewed. The developed photosensitive layers are masked from view by 
the light-reflecting layer and remain with the receiving layer 46 as part 
of a permanent laminate. The rupturable container 30 is of the type shown 
in U.S. Pat. No. 2,543,181 and is positioned adjacent the leading edge of 
the film unit. 
In the processing of the film unit, the film unit is advanced relative to 
and between a pair of pressure-applying members which apply compressive 
pressure to the rupturable container 30 to eject its liquid contents 
between the photosensitive and image-receiving components 2 and 4 and then 
distribute the mass of liquid between the sheets toward the trailing ends 
thereof to form a layer of substantially uniform, predetermined thickness 
at least co-extensive with the image area. In order to insure sufficient 
processing liquid to form a layer of the required area and thickness 
between the sheets, excess processing liquid may be provided in container 
30 and trapping means (not shown) provided for collecting and retaining 
excess processing liquid overrun. Details of the various layers of this 
and of the film unit of FIG. 1 may be found in the herein cited patents 
and applications and need not be recited here. 
Processing of film units of the type described in FIG. 2 is initiated by 
distributing the processing composition between predetermined layers of 
the film unit. In exposed and developed areas, the dye developer will be 
immobilized as a function of development. In unexposed and undeveloped 
areas, the dye developer is unreacted and diffusible, and this provides an 
imagewise distribution of unoxidized dye developer, diffusible in the 
processing composition, as a function of the point-to-point degree of 
exposure of the silver halide layer. The desired transfer image is 
obtained by the diffusion transfer to the image-receiving layer of at 
least part of this imagewise distribution of unoxidized dye developer. In 
the illustrated embodiment, the pH of the photographic system is 
controlled and reduced by the neutralization of alkali after a 
predetermined interval, in accordance with the teachings of the above 
noted U.S. Pat. No. 3,615,644, to reduce the alkalinity to a pH at which 
the unoxidized dye developer is substantially insoluble and 
non-diffusible. As will be readily recognized, the details of such 
processes form no part of the present invention but are well known; the 
previously noted U.S. patents may be referred to for more specific 
discussion of such processes. 
Multicolor images may be obtained by providing the requisite number of 
differentially exposable silver halide emulsions, and said silver halide 
emulsions are most commonly provided as individual layers coated in 
superposed relationship. Film units intended to provide multicolor images 
comprise two or more selectively sensitized silver halide layers each 
having associated therewith an appropriate image dye-providing material 
providing an image dye having spectral absorption characteristics 
substantially complementary to the light by which the associated silver 
halide is exposed. The most commonly employed negative components for 
forming multicolor images are of the "tripack" structure and contain 
blue-, green-, and red-sensitive silver halide layers each having 
associated therewith in the same or in a contiguous layer a yellow, a 
magenta and a cyan image dye-providing material respectively. Interlayers 
or spacer layers may, if desired, be provided between the respective 
silver halide layers and associated image dye-providing materials or 
between other layers. Integral multicolor photosensitive elements of this 
general type are disclosed in U.S. Pat. No. 3,345,163 issued Oct. 3, 1967 
to Edwin H. Land and Howard G. Rogers as well as in the previously noted 
U.S. patents, e.g., in FIG. 9 of the aforementioned U.S. Pat. No. 
2,983,606. 
A number of modifications to the structures described in connection with 
FIG. 2 will readily suggest themselves to one skilled in the art. Thus, 
for example, the multicolor multilayer negative may be replaced by a 
screen-type negative as illustrated in U.S. Pat. No. 2,968,554 issued Jan. 
17, 1961 to Edwin H. Land and in the aforementioned U.S. Pat. No. 
2,983,606 particularly with respect to FIG. 3 thereof. 
The image dye-providing materials which may be employed in such processes 
generally may be characterized as either (1) initially soluble or 
diffusible in the processing composition but are selectively rendered 
non-diffusible in an imagewise pattern as a function of development; or 
(2) initially insoluble or non-diffusible in the processing composition 
but which are selectively rendered diffusible or provide a diffusible 
product in an imagewise pattern as a function of development. These 
materials may be complete dyes or dye intermediates, e.g., color couplers. 
The requisite differential in mobility or solubility may, for example, be 
obtained by a chemical action such as a redox reaction or a coupling 
reaction. 
As examples of initially soluble or diffusible materials and their 
application in color diffusion transfer, mention may be made of those 
disclosed, for example, in U.S. Pat. Nos. 2,774,668; 2,968,554; 2,983,606; 
3,087,817; 3,185,567; 3,230,082; 3,345,163; and 3,443,943. As examples of 
initially non-diffusible materials and their use in color transfer 
systems, mention may be made of the materials and systems disclosed in 
U.S. Pat. Nos. 3,185,567; 3,719,489; 3,443,939; 3,443,940; 3,227,550; 
3,227,552; and 4,076,529. Many types of image dye-providing substances and 
film units useful therewith also are discussed in the aforementioned U.S. 
Pat. No. 3,647,437 to which reference may be made. 
It is also to be understood that "direct positive" silver halide emulsions 
may also be used, depending upon the particular image dye-providing 
substances employed and whether a positive or negative color transfer 
image is desired. 
A preferred opacification system to be contained in the processing 
composition to effect processing outside of a camera is that described in 
the above-mentioned U.S. Pat. No. 3,647,437, and comprises a dispersion of 
an inorganic light-reflecting pigment which also contains at least one 
light-absorbing agent, i.e., optical filter agent, at a pH above the pKa 
of the optical filter agent in a concentration effective when the 
processing composition is applied, to provide a layer exhibiting optical 
transmission density&gt;than about 6.0 density units with respect to incident 
radiation actinic to the photosensitive silver halide and optical 
reflection density&lt;than about 1.0 density units with respect to incident 
visible radiation. 
In lieu of having the light-reflecting pigment in the processing 
composition, the light-reflecting pigment used to mask the photosensitive 
strata and to provide the background for viewing the color transfer image 
formed in the receiving layer may be present initially in whole or in part 
as a preformed layer in the film unit. As an example of such a preformed 
layer, mention may be made of that disclosed in U.S. Pat. No. 3,615,421 
issued Oct. 26, 1971 and in U.S. Pat. No. 3,620,724 issued Nov. 16, 1971, 
both in the name of Edwin H. Land. The reflecting agent may be generated 
in situ as is disclosed in U.S. Pat. Nos. 3,647,434 and 3,647,435, both 
issued Mar. 7, 1972 to Edwin H. Land. 
The dye developers (or other image dye-providing substances) are preferably 
selected for their ability to provide colors that are useful in carrying 
out subtractive color photography, that is, the previously mentioned cyan, 
magenta and yellow. They may be incorporated in the respective silver 
halide emulsion or, in the preferred embodiment, in a separate layer 
behind the respective silver halide emulsion. Thus, a dye developer may, 
for example, be in a coating or layer behind the respective silver halide 
emulsion and such a layer of dye developer may be applied by use of a 
coating solution containing the respective dye developer distributed, in a 
concentration calculated to give the desired coverage of dye developer per 
unit area, in a film-forming natural, or synthetic, polymer, for example, 
gelatin, polyvinyl alcohol, and the like, adapted to be permeated by the 
processing composition. 
Dye developers, as noted above, are compounds which contain the 
chromophoric system of a dye and also a silver halide developing function. 
By "a silver halide developing function" is meant a grouping adapted to 
develop exposed silver halide. A preferred silver halide development 
function is a hydroquinonyl group. Other suitable developing functions 
include ortho-dihydroxyphenyl and ortho- and paraamino substituted 
hydroxyphenyl groups. In general, the development function includes a 
benzenoid developing function, that is, an aromatic developing group which 
forms quinonoid or quinone substances when oxidized. 
The image-receiving layer may comprise one of the materials known in the 
art, such as polyvinyl alcohol, gelatin, etc. It may contain agents 
adapted to mordant or otherwise fix the transferred image dye(s). 
Preferred materials comprise polyvinyl alcohol or gelatin containing a dye 
mordant such as poly-4-vinylpyridine, as disclosed in U.S. Pat. No. 
3,148,061 and graft copolymers containing 4-vinylpyridine as disclosed in 
U.S. Pat. No. 3,756,814. 
In the various color diffusion transfer systems which have previously been 
described and which employ an aqueous alkaline processing fluid, it is 
well known to employ an acid-reacting reagent in a layer of the film unit 
to lower the environmental pH following substantial dye transfer in order 
to increase the image stability and/or to adjust the pH from the first pH 
at which the image dyes are diffusible to a second (lower) pH at which 
they are not. For example, the previously mentioned U.S. Pat. No. 
3,415,644 discloses systems wherein the desired pH reduction may be 
effected by providing a polymeric acid layer adjacent the dyeable stratum. 
These polymeric acids may be polymers which contain acid groups, e.g., 
carboxylic acid and sulfonic acid groups, which are capable of forming 
salts with alkali metals or with organic bases; or potentially 
acid-yielding groups such as anhydrides or lactones. Preferably the acid 
polymer contains free carboxyl groups. Alternatively, the acid-reacting 
reagent may be in a layer adjacent to the silver halide most distant from 
the image-receiving layer, as disclosed in U.S. Pat. No. 3,573,043 issued 
Mar. 30, 1971 to Edwin H. Land. Another system for providing an 
acid-reacting reagent is disclosed in U.S. Pat. No. 3,576,625 issued Apr. 
27, 1971 to Edwin H. Land. 
An inert interlayer or spacer layer may be and is preferably disposed 
between the polymeric acid layer and the dyeable stratum in order to 
control or "time" the pH reduction so that it is not premature and 
interferes with the development process. Suitable spacer or "timing" 
layers for this purpose are described with particularity in U.S. Pat. Nos. 
3,362,819; 3,419,389; 3,421,893; 3,455,686; and 3,575,701. 
While the acid layer and associated spacer layer are preferably contained 
in the positive component employed in systems wherein the dyeable stratum 
and photosensitive strata are contained on separate supports, e.g., 
between the support for the receiving element and the dyeable stratum; or 
associated with the dyeable stratum in those integral film units, e.g., on 
the side of the dyeable stratum opposed from the negative components, they 
may, if desired, be associated with the photosensitive strata, as is 
disclosed, for example, in U.S. Pat. Nos. 3,362,821 and 3,573,043. In film 
units such as those described in the aforementioned U.S. Pat. Nos. 
3,594,164 and 3,594,165, they also may be contained on the spreader sheet 
employed to facilitate application of the processing fluid. 
As is now well known and illustrated, for example, in the previously cited 
patents, the liquid processing composition referred to for effecting 
multicolor diffusion transfer processes comprises at least an aqueous 
solution of an alkaline material, for example sodium hydroxide, potassium 
hydroxide, and the like, and preferably possessing a pH in excess of 12, 
and most preferably includes a viscosity-increasing compound constituting 
a film-forming material of the type which, when the composition is spread 
and dried, forms a relatively firm and relatively stable film. The 
preferred film-forming materials comprise high molecular weight polymers 
such as polymeric, water-soluble ethers which are inert to an alkaline 
solution such as, for example, a hydroxyethyl cellulose or sodium 
carboxymethyl cellulose. Other film-forming materials or thickening agents 
whose ability to increase viscosity is substantially unaffected if left in 
solution for a long period of time also are capable of utilization. The 
film-forming material is preferably contained in the processing 
composition in such suitable quantities as to impart to the composition a 
viscosity in excess of 100 cps, at a temperature of approximately 
24.degree. C. and preferably in the order of 100,000 cps to 200,000 cps at 
that temperature. 
In particularly useful embodiments, the transparent polymeric support 
contains a small quantity of a pigment, e.g., carbon black, to prevent fog 
formation due to light-piping by internal reflection within the 
transparent support, and subsequent exiting from the support surface 
carrying the photographic layers, of actinic light incident upon an edge 
thereof; such elements are described in Belgian Pat. No. 777,407. The 
transparent support advantageously may include an ultraviolet light 
absorber. 
For purposes of illustrating the invention, a solution of a sample of the 
compound of the Example was incorporated into the image-receiving layer 3 
of an image-receiving component comprising the structure set forth below 
by mixing the solution of the compound with a solution of the graft 
copolymer and coating this mixture on top of the timing layer to complete 
the image-receiving component. 
A transparent 4 mil polyethylene terephthalate film base coated with, in 
succession: 
1. as a polymeric acid layer, a mixture of about 9 parts of a partial butyl 
ester of polyethylene/maleic anhydride copolymer and 1 part of polyvinyl 
butyral coated at a coverage of about 2,500 mgs./ft..sup.2 ; 
2. a timing layer containing a 14:1 ratio of a 60-30-4-6 tetrapolymer of 
butyacrylate, diacetone acrylamide, styrene and methacrylic acid and 
polyvinyl alcohol at a coverage of 500 mgs./ft..sup.2 ; 
3. a graft copolymer of 4-vinylpyridine and 
vinylbenzyltrimethylammoniumchloride grafted on hydroxyethyl cellulose in 
a weight ratio of 2.2/1/2.2, respectively, coated at a coverage of 300 
mgs./ft..sup.2 to provide an image-receiving layer and containing the 
selected dye compound. 
The image-receiving component containing the dye compound was placed on a 
piece of gelatin coated Mylar, and the transmission densities for red (R), 
green (G) and blue (B) were recorded on a transmission densitometer. Then 
several drops of aqueous 1 N KOH were added to the gelatin sheet, and the 
image-receiving component was lightly pressed against the gelatin sheet to 
"bleach" the dye compound. After about 60 seconds, the transmission 
densities were again recorded for red (R), green (G) and blue (B) for the 
"sandwich". The results are set forth below. 
______________________________________ 
Transmission Densities 
Before Bleaching After Bleaching 
R G B R G B 
______________________________________ 
.01 .15 .00 .02 .01 .01 
______________________________________ 
The densitometer was set at 0.00 for R, G, B with two pieces of gelatin 
coated Mylar in the light beam. 
From these results, it can be seen that the subject dyes are effective in 
absorbing radiation within a certain wavelength range, and when treated 
with aqueous alkali are "bleached", i.e., decolorized. 
It will be appreciated that various solvents may be employed for dispersing 
the dyes in the image-receiving or other appropriate layer of the 
photographic product and that useful solvents may be readily selected for 
a given compound. Also, it will be understood that where the anion may 
possibly have an adverse effect on the photosensitive material, the dye 
will be positioned other than in the silver halide emulsion layer(s), and 
depending upon the mobility of the dye in a given matrix or binder, it may 
be desirable to employ an immobilizing group or a group that will mordant 
to the matrix to prevent migration of the dye, particularly, where the 
photographic product is subjected to conditions of high temperature and 
high humidity prior to use. 
Also, it will be appreciated that in utilizing the subject dyes to correct 
color balance, for example, in multicolor diffusion transfer photographic 
film units that a photosensitive element may be exposed to a suitable 
multicolor step-wedge and diffusion transfer processed with a given 
processing composition and image-receiving element. The blue, green and 
red D log E curves of the resulting multicolor transfer image (sample 
image) are then prepared. Examination of these D log E curves will 
indicate to one skilled in color photographic sensitometry the manner and 
extent to which the individual D log E curves depart from the desired 
curve shape. From this examination, one may determine by routine analysis 
and experimentation how much filtration would be required of what 
wavelength range or ranges to obtain a more desirable color balance. The 
photosensitive element of another film unit, having the identical 
photosensitive element, image-receiving element and processing composition 
as used in obtaining the sample image, is then given the same exposure 
through a conventional color correction filter(s) of the color and density 
estimated to be necessary to provide the desired changes in the D log E 
curves of the sample image. The blue, green and red D log E curves of the 
resulting test multicolor transfer image are then prepared and compared 
with the sample. While more than one "test" may be required to determine 
the color filtration most effective to give the desired D log E curve 
shape changes, such tests may be performed rapidly and easily. When the 
appropriate color filtration has been determined, a layer containing a 
color correction dye or dyes absorbing light in appropriate wavelength 
range(s) is coated on a transparent support at a coverage calculated to 
provide the requisite density. This "test" color correction dye layer is 
placed in the exposure path and the previous exposure test repeated. 
Analysis of the D log E curves of the resulting multicolor transfer image 
will indicate what changes, if any, should be made in the spectral 
absorption range and density prior to incorporating a corresponding color 
correction dye layer into the diffusion transfer film unit. 
It will be recognized that effecting photoexposure through a layer 
containing the subject dye(s) is effective to "filter", i.e., decrease the 
exposure given to the silver halide layer(s) exposable by light absorbed 
by said color correction dye(s) and that one or more dyes of the present 
invention may be used in conjunction with other filter dyes for effecting 
changes in one, two or all three of the individual red, green and blue H 
and D curves to achieve the desired color balance. Though the subject dyes 
find particular utility in diffusion transfer and other photographic film 
units where it is desired to bleach the dye(s) during processing 
subsequent to photoexposure through the dye layer(s), the subject dyes 
also may be employed in diffusion transfer and other film units where the 
dye is so positioned as not to contribute dye density to the transfer or 
final image. Where the filter dye layer through which photoexposure has 
been made is not part of the transfer image, or where the final image is 
masked from view as in certain integral negative-positive reflection print 
structures, the "unbleached" filter dye should be non-diffusible to the 
image-receiving layer containing the transfer image. The requisite 
non-diffusion character may be provided by the use of a suitable mordant, 
by the use of long chain "ballast" or "anchor" substituents and/or other 
art known techniques. 
As noted in the above example, in integral diffusion transfer film units, 
the color correction dye(s) may be incorporated in the image-receiving 
layer. The choice of location of the color correction dye(s) will depend 
in large part upon what stage of the manufacturing process the 
determination is made to incorporate such a color correction dye. As will 
be readily apparent, provision of the color correction dye(s) in a 
separate layer has the advantage of permitting modification after the 
components have fully "matured" and also permits different modification of 
portions of the same lot of the positive component. 
The supports for the various layers may be any of the types known in the 
art to be useful. In the preferred embodiments wherein an integral 
negative-positive reflection print is obtained, the supports should be 
dimensionally stable and may be polyethylene terephthalate or other 
polymeric film base, as disclosed in the cross-referenced patents. 
It will be recognized that the transfer image formed following exposure and 
processing of film units of the type illustrated in FIG. 2 will be a 
geometrically reversed image of the subject. Accordingly, to provide 
geometrically non-reversed transfer images, exposure of such film units 
should be accomplished through an image reversing optical system, such as 
in a camera possessing an image reversing optical system utilizing mirror 
optics, e.g., as described in U.S. Pat. No. 3,447,437 issued June 3, 1969 
to Douglas B. Tiffany. 
Where the expression "positive image" has been used, this expression should 
not be interpreted in a restrictive sense since it is used primarily for 
purposes of illustration, in that it defines the image produced on the 
image-carrying layer as being reversed, in the positive-negative sense, 
with respect to the image in the photosensitive emulsion layers. As an 
example of an alternative meaning for "positive image", assume that the 
photosensitive element is exposed to actinic light through a negative 
transparency. In this case, the latent image in the photosensitive 
emulsion layers will be positive and the dye image produced on the 
image-carrying layer will be negative. The expression "positive image" is 
intended to cover such an image produced on the image-carrying layer, as 
well as transfer images obtained by use of direct positive silver halide 
emulsions to provide a "positive" image of the photographed subject. 
While the usefulness of the subject xanthene dyes has been illustrated as 
applied to integral diffusion transfer film units where the transfer image 
is retained with the developed photosensitive element as part of a 
permanent laminate, it will be understood that the xanthene dyes of this 
invention also may be used to provide antihalo, color correction or other 
light filtering layer(s) in diffusion transfer film units where the 
transfer image, either in silver or in dye, is separated from the 
developed photosensitive layer(s) subsequent to processing. Though the 
image dye-providing materials are preferably dye developers, it will be 
appreciated that other types of image dyes and dye intermediates may be 
employed to provide the dye transfer image. 
Besides their usefulness in diffusion transfer photographic products and 
processes, the xanthene dyes of the present invention also may be used in 
filter layers of conventional photographic materials, for example, in 
antihalation or color correction layers in conventional negatives, and may 
be disposed in the appropriate layer(s) in an amount sufficient to provide 
the desired filtering effect. The selection and incorporation of the 
xanthene dye for the desired filtering effect may be accomplished in a 
known manner using conventional techniques and is well within the skill of 
the art. For example, for color correction purposes, the dye(s) selected 
may absorb light within a specific wavelength range, e.g., blue, green or 
red light, or within a combination of several wavelength ranges and will 
be disposed in a layer through which photoexposure is made. Indeed, it may 
be desirable in a given instance to filter light of two different 
wavelength ranges in a ratio such that one silver halide emulsion receives 
more exposure filtration than does another. As in the diffusion transfer 
film units, the dye(s) selected for color correction are advantageously 
applied after the photosensitive element has aged to "maturity", i.e., the 
sensitometry of the photosensitive element as manufactured is no longer 
changing significantly with time. Where the subject dyes are employed for 
antihalation purposes, they may be incorporated, for example, in a layer 
on one or both sides of a support carrying the photosensitive layer(s) and 
where they are employed as optical filter agents, they will be so 
positioned as to prevent post-exposure fogging during processing in 
ambient light without, of course, interfering with imagewise exposure of 
the photosensitive layer(s) or with viewing of the final image. 
Since certain changes may be made in the hereinafter defined subject matter 
without departing from the scope of the invention herein involved, it is 
intended that all matter contained in the above description and examples 
be interpreted as illustrative and not in a limiting sense.