Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Identified radiation sensitive composition with color...
Reexamination Certificate
1999-12-28
2001-03-06
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Identified radiation sensitive composition with color...
C430S376000, C430S383000, C430S552000, C430S554000
Reexamination Certificate
active
06197489
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an improved silver halide photographic element for silver halide imaging systems. More specifically, it relates to such an element containing four separately sensitized light-sensitive silver halide emulsion layers comprising, in addition to the three conventional cyan, magenta, and yellow dye-forming layers, a fourth dye-forming layer comprising a coupler wherein the dye formed by that coupler has a hue angle in the range of 225-310°, which increases the gamut of colors possible.
BACKGROUND OF THE INVENTION
Color gamut is an important feature of color printing and imaging systems. It is a measure of the range of colors that can be produced using a given combination of colorants. It is desirable for the color gamut to be as large as possible. The color gamut of the imaging system is controlled primarily by the absorption characteristics of the set of colorants used to produce the image. Silver halide imaging systems typically employ three colorants, typically including cyan, magenta, and yellow in the conventional subtractive imaging system
The ability to produce an image containing any particular color is limited by the color gamut of the system and materials used to produce the image. Thus, the range of colors available for image reproduction is limited by the color gamut that the system and materials can produce.
Color gamut is often thought to be maximized by the use of so-called “block dyes”. In
The Reproduction of Colour
4th ed., R. W. G. Hunt, pp 135-144, it has been suggested that the optimum gamut could be obtained with a subtractive three-color system using three theoretical block dyes where the blocks are separated at approximately 490 nm and 580 nm. This proposal is interesting but cannot be implemented for various reasons. In particular, there are no real organic-based couplers which produce dyes corresponding to the proposed block dyes.
Variations in the block dye concept are advanced by Clarkson, M., E., and Vickerstaff, T., in “Brightness and Hue of Present-Day Dyes in Relation to Colour Photography,” Photo. J. 88b, 26 (1948). Three example spectral shapes are given by Clarkson and Vickerstaff: Block, Trapezoidal, and Triangular. The authors conclude, contrary to the teachings of Hunt, that trapezoidal absorption spectra may be preferred to a vertical sided block dye. Again, dyes having these trapezoidal spectra shapes are theoretical and are not available in practice.
Both commercially available dyes and theoretical dyes were investigated in “The Color Gamut Obtainable by the Combination of Subtractive Color Dyes. Optimum Absorption Bands as Defined by Nonlinear Optimization Technique,” J. Imaging Science, 30, 9-12. The author, N. Ohta, deals with the subject of real colorants and notes that the existing curve for a typical cyan dye, as shown in the publication, is the optimum absorption curve for cyan dyes from a gamut standpoint.
McInerney, et al, in U.S. Pat. Nos. 5,679,139; 5,679,140; 5,679,141; and 5,679,142 teach the shape of preferred subtractive dye absorption shapes for use in four color, C,M,Y,K based ink-jet prints.
McInerney, et al, in EP 0825,488 teaches the shape of preferred subtractive cyan dye absorption shape for use in silver halide based color prints.
Kitchin, et al, in U.S. Pat. No. 4,705,745, teach the preparation of a photographic element for preparing half-tone color proofs comprising four separate imaging layers capable of producing cyan, magenta, yellow and black images.
Powers, et al, in U.S. Pat. No. 4,816,378, teach an imaging process for the preparation of color half-tone images that contain cyan, magenta, yellow and, black images. The use of the black dye does little to improve the gamut of color reproduction.
Haraga, et al, in EP 0915374A1, teach a method for improving image clarity by mixing ‘invisible’ information in the original scene with a color print and reproducing it as an infrared dye, magenta dye or as a mixture of cyan magenta and yellow dyes to achieve improved color tone and realism. The addition of the resulting infrared, magenta or black dye does little to improve the gamut.
In spite of the foregoing teachings relative to color gamut, the coupler sets which have been employed in silver halide color imaging have not provided the range of gamut desired for modem digital imaging; especially for so-called ‘spot colors’, or ‘HiFi colors’.
It is therefore a problem to be solved to provide an improved silver halide color photographic element and process that provides an increase in color gamut and improved accuracy of color reproduction.
SUMMARY OF THE INVENTION
The invention provides a color photographic element comprising at least four imaging layers including:
a first light sensitive silver halide imaging layer having associated therewith a cyan image dye-forming coupler;
a second light sensitive silver halide imaging layer having associated therewith a magenta image dye-forming coupler;
a third light sensitive silver halide imaging layer having associated therewith a yellow image dye-forming coupler; and
a fourth light sensitive silver halide imaging layer having associated therewith a fourth image dye-forming coupler for which the normalized spectral transmission density distribution curve of the dye formed by the fourth image dye-forming coupler upon reaction with color developer has a CIELAB hue angle, h
ab
, from 225 to 310°. The invention also provides a process for forming an image in an element of the invention.
Elements and processes of the invention provide a greater color gamut and improved accuracy of color reproduction.
DETAILED DESCRIPTION OF THE INVENTION
The invention is summarized in the preceding section. The photographic element of the invention employs subtractive color imaging. In such imaging, a color image is formed by generating a combination of cyan, magenta, yellow and ‘blue’ colorants in proportion to the amounts of exposure of 4 different digitally controlled light sources respectively. The object is to provide a reproduction that is pleasing to the observer but also has the improved capability to specifically reproduce the so-called ‘spot colors’, Pantone® colors or Hi-Fi colors. Color in the reproduced image is composed of one or a combination of the cyan, magenta and yellow and ‘blue’ image colorants. The relationship of the original color to the reproduced color is a combination of many factors. It is, however, limited by the color gamut achievable by the multitude of combinations of colorants used to generate the final image.
In addition to the individual colorant characteristics, it is necessary that the ‘blue’ colorant have a desired absorption band shape which functions to provide an optimum overall color gamut.
The CIELAB metrics, a*, b*, and L*, when specified in combination, describe the color of an object, whether it be red, green, blue (under fixed viewing conditions, etc). The measurement of a*, b*, and L* are well documented and now represent an international standard of color measurement. (The well-known CIE system of color measurement was established by the International Commission on Illumination in 1931 and was further revised in 1976. For a more complete description of color measurement refer to “Principles of Color Technology, 2nd Edition by F. Billmeyer, Jr. and M. Saltzman, published by J. Wiley and Sons, 1981.)
L* is a measure of how light or dark a color is. L*=100 is white. L*=0 is black. The value of L* is a function of the Tristimulus value Y, thus
L*=116(Y/Y
n
)
⅓
−16
Simply stated, a* is a measure of how green or magenta the color is (since they are color opposites) and b* is a measure of how blue or yellow a color is. From a mathematical perspective, a* and b* are generally determined as follows:
a
*=500{(X/X
n
)
⅓
−(Y/Y
n
)
⅓
}
b
*=200{(Y/Y
n
)
⅓
−(Z/Z
n
)
⅓
}
where X, Y and Z are the Tristimulus values obtained from the combination of the visible reflectance spectrum of the object, the illumina
Begley William J.
Edwards James L.
Arthur E. Kluegel
Eastman Kodak Company
Le Hoa Van
LandOfFree
Photographic element for color imaging does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Photographic element for color imaging, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Photographic element for color imaging will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2453151