Travelling mat backing

The present invention provides an improved backing screen having particular application for use in composite photography. In particular, the present invention relates to color difference composite photography, whether still, motion picture, video, solid state digital electronic or electrophotographic imaging, in which foreground and background scenes are separately recorded and subsequently combined using known "blue screen" or special color background techniques to form a single image. The present invention includes a biaxially stretchable fabric of synthetic fibers treated with a dye formulation, including fluorescence which is reactive to the visible spectrum, to achieve any of a variety of specific spectral loci and luminances, for the purpose of providing a precise chromatic actinic stimulus response for a silver halide photographic film, or similar response for electronic imaging devices. The selected backing is deployed in a support such that the fabric is stretched to a smooth, featureless surface and then illuminated. Foreground subject matter interposed between the camera and the backing or directly on the backing will therefore be readily distinguished and "matted" for compositing by methods well known to the art. In a further aspect of the present invention, the light emitting characteristics of the fluorescent matte fabric of the present invention may be advantageously relied upon to obtain the desired lighting effect in, for example, underwater photography. In yet another embodiment of the present invention, the matte fabric of the present invention may be configured to cover objects or parts of a person in a field of view.

BACKGROUND OF THE INVENTION 
1. Field of Invention 
The present invention relates to composite photography, and more 
particularly to backing screens having improved chromatic actinic stimulus 
for color difference composite photography, cinematography, videography 
and solid state digital imaging. 
2 . Art Background 
In motion picture production, it is often impractical, impossible or simply 
uneconomical to place actors in the specific environments to be depicted. 
To resolve this problem, various techniques have evolved over the years to 
composite such scenes from separately filmed "elements." The patent 
literature contains a great deal of teaching in this field. A 
comprehensive discussion is to be found in my prior patents. See U.S. Pat. 
Nos. 4,417,791, 4,548,470 and especially 4,629,298. Reference is also made 
to the American Cinematographer Manual, Seventh Edition (hereinafter "the 
ASC Manual") pp. 430-466, with particular emphasis on the section titled 
"Screen Types and Lighting" pp. 434-437. With these references in mind, 
the present discussion will be confined to a summary of the evolution of 
traveling matte technique. 
The earliest efforts at composite photography generally resorted to 
animation, as in Georges Melies' "Trip to the Moon" (1902). Thereafter, 
techniques such as the "held/take" process were utilized, in which a scene 
was shot with predetermined areas of the successive frames blocked off 
with an opaque `matte` in order to preclude exposure thereof. The 
unexposed portions of the successive frames were thereafter exposed to the 
desired foreground subjects, with the background areas "matted" to protect 
the previously recorded latent images. Essentially the same process is 
used to incorporate a painting which depicts a distant, dangerous, or 
totally alien scene against which the actors are to appear; this is known 
as matte painting. In order to depict actors or other foreground subjects 
moving in front of the desired background scenes, it became necessary to 
produce "mattes" that would change from frame to frame, or "travel." 
Various techniques were developed over the years to accomplish this. 
Early processes relied upon contrast alone, the foreground action being 
filmed against a jet black backing and the resulting image being printed 
through several generations of high contrast film stock or alternatively, 
having the image chemically "intensified" until a matte was produced. One 
example of this technique is described in U.S. Pat. No. 1,273,435 to Frank 
Williams in 1918. 
The results obtained by this technique were generally quite poor, due to 
the inevitable distortion produced by the multiple reversals or the 
intensification which result in "haloes" or "fringes" occurring between 
the scene elements. Efforts to address these problems led to the 
exploitation of the chromatic response of black and white photographic 
film and resulted in the Dunning-Pomeroy process (U.S. Pat. No. 1,613,163 
to Carrol D. Dunning, 1927) and another Williams process (U.S. Pat. No. 
2,024,081, Dec. 10, 1935). With the advent of color film recording, 
notably the Technicolor process, the chromatic based systems began to 
proliferate. (See U.S. Pat. Nos. 2,693,126, and 2,740,712 to W. E. Pohl.). 
The fundamental concept that makes it possible to derive a matte from a 
polychromatic photographic image is based on the fact that the 
superimposition of positive and negative images will cancel each other out 
and yield an opaque image. Thus it follows that if a given portion of the 
image is comprised of a pure monochromatic object, e.g., blue, this 
portion will appear as light in a print of the film record that is 
sensitive to blue and dark in prints of the film records that are not 
sensitive to blue, i.e. the red and green records. Therefore, if the red 
negative record, in which the "blue" object appears light, is superimposed 
with the blue positive record, in which the blue object also appears 
light, the blue object will remain the only significant "light" object in 
the scene, all polychromatic portions of the scene having canceled each 
other out to yield an opaque image. It is then straightforward to produce 
a set of positive and negative high contrast "mattes" and employ these to 
print, in succession, the foreground and background elements of a 
composite scene. 
With the advent of monopak color photographic film it became possible to 
devise the ever more sophisticated color difference traveling matte 
techniques exemplified by Petro Vlahos' U.S. Pat. No. 3,158,477. As the 
compositing technology evolved to produce more convincing results, the 
requirements for the original photography of the "bluescreen" element 
became increasingly severe. Much ingenious attention was focussed on this 
area, and some of the results achieved have been recognized with patents 
and Academy of Motion Picture Arts and Sciences Scientific and Engineering 
Awards. Among these are: Eastman Kodak for color negative EC 5295, a film 
designed expressly for Bluescreen traveling matte photography (1987), the 
Stewart Traveling Matte Transmission Bluescreen backing (1964), the 
Blue-Max Blue Flux Front Projector (1984) (U.S. Pat. No. 4,629,298) and 
the Reverse Bluescreen Process (1983) (U.S. Pat. No. 4,417,791). The 
ultimate sophistication in traveling matte image acquisition is achieved 
with the Reverse Front Projection process described in the American 
Cinematogpher Manual, p. 457, which solves a host of problems. This 
technique provides great control over chrominance and luminance and 
essentially cancels any prospect of "spill" and unwanted reflections. 
The latest advances in compositing technology exploit the capacity of 
computer image manipulation processes and digital film scanning and 
printing techniques, and have vastly expanded the application and efficacy 
of composite photography. The catalogue of Petro Vlahos' patents in the 
field traces the development and increasing sophistication of electronic 
compositing. While the below listed patents describe the electronic 
hardware embodiments of the process, these have all now been implemented 
in computer software for digital electronic composites: 
U.S. Pat. No. 3,595,987 
U.S. Pat. No. 4,007,487 
U.S. Pat. No. 4,100,569, 
U.S. Pat. No. 4,344,085 
U.S. Pat. No. 4,409,611 
U.S. Pat. No. 4,589,023 
U.S. Pat. No. 4,625,231 
In Ultimatte (Vlahos) matte extraction logic, as applied to digital film 
composites today, the process (while still quite similar), is freed from 
confinement to the Blue record and readily incorporates garbage and window 
mattes without any compromise of the finely detailed continuous tone 
feature. 
The starting point for a digital blue or green screen color difference 
composite is a matte generated by subtracting the value of one color from 
the value of another for each pixel in the image. (Whether this is 
accomplished through software or through analog video circuitry, the net 
effect is the same.) 
With Blue logic, the raw matte is a greyscale image whose value at each 
point is simply the amount by which Blue exceeds the higher of the other 
two colors. The result is a matte which is dead black anywhere Blue is 
less than Red or Green and some shade of grey wherever Blue is predominant 
primary color. 
This matte is subjected to a variety of adjustments before it is used to 
process the foreground and background images, but the crucial point is 
that the matte is generated from the absolute levels of the color 
components for each pixel. A pixel having values of 200 Blue, 100 Green 
and 100 Red will yield a pixel with a value of 100 in the matte while a 
darker pixel of the same hue with values of 100 Blue, 50 Green and 50 Red 
will yield a matte value of 50. 
In other words, the Ultimatte electronic or digital color difference 
matting process is a function of the luminance or brightness of the 
backing as well as the chrominance (hue) or purity of its color and the 
uniformity or consistency of the matte field. 
What emerges quite clearly from this description of how the Ultimatte (and 
other comparable matte extraction programs) work is that chrominance (the 
purity of the backing color), luminance (the brightness of the backing 
color) and uniformity (the lowest possible variations in chroma and 
luminance) are all crucial to the process of creating a matte and to the 
subsequent composite image. 
In 1992, Eastman Kodak Company developed an effective film digitizing 
scanner and a complementary film printing laser. These systems and others 
produced by different manufacturers provide extensive software programs 
covering every facet of compositing and image manipulation technique. It 
is now possible to create composites containing an infinite number of 
elements without any degradation of image quality from the original 
digital scan through to the laser film output. The most subtle image 
attributes can be retained, including extremely fine detail such as 
strands of hair, as well as the all important motion blurred edges of 
moving objects. Translucent objects such as glass, water and smoke may now 
be routinely rendered in totally convincing "seamless" composites. 
The extremely high demands such sophisticated computer compositing programs 
make on original traveling matte photography can demonstrably be met by 
the previously described technology such as Blue-Max (R) front projection, 
Reverse Front Projection and the like. However, these techniques, as 
sophisticated in their way as the computer programs, are technologically 
complex and time consuming to employ. The immense proliferation of 
composite photography occasioned by the facility and efficacy of digital 
composite technology require the development of simple, effective and 
economical techniques for achieving the original image or "bluescreen 
element." 
Throughout this discussion, the process has been described by the term 
"Bluescreen." This is explained by the fact that for most of the history 
of the process, the backing color of choice, and frequently of necessity, 
has been blue. While it is possible to perform photochemical optical 
traveling matte composites using any primary color backing, there has been 
a persuasive technological rationale for confining the process to the blue 
version. With the advent of the digital electronic processes described 
above, however, the range of backing colors is expanded to include all the 
primaries and indeed, their complements. Further, freed from the 
constraints entailed in the photochemical process, the advantages to be 
found in matting on the green record can now be readily accessed. A full 
discussion of the relative merits of blue versus green is not warranted 
here beyond the mention of some of the more obvious attributes involved. 
In monopak color film, particularly that balanced for Tungsten light, the 
Blue sensitive record is, of necessity, comprised of a fast, and hence, 
grainier record than either Red or Green. This is due to the relative 
paucity of blue light available in the Tungsten spectrum. In fact, the 
film emulsion designers make a major effort to provide the green record 
with the highest possible image attributes. Thus many aspects of perceived 
image quality such as resolution, tone scale, acutance, and so on are 
delivered to the viewer via the green record of the monopak color film. (A 
similar situation also prevails in video imaging devices, where the 
bandwidth assigned to the respective color channels was derived from the 
visual response of the human eye; thus the Green channel is some 59%, 
versus approximately 30% for the Red and only 11% for the Blue.) In most 
photochemical compositing techniques, this attribute of the green record 
was superfluous, as the "matte" record, usually blue, was reduced to a 
high contrast black and white matte. By contrast, in a sophisticated 
digital electronic computer compositing system, the matte record is 
rendered as a continuous tone black and white image. Actually, the matte 
should no longer be thought of as an "image," but rather as a signals 
matrix containing the instructions for combining the relative proportions 
of both foreground and background picture elements (or pixels) which will 
comprise the eventual composite image. This is now known as the Alpha 
channel. For a comprehensive discussion of the Alpha channel, see 
"Compositing Digital Images," Thomas Porter and Tom Duff, in Computer 
Graphics , Vol. 18, No. 3, p. 254, July 1984, in which the concept was 
introduced. Mattes produced using this technology are capable of readily 
reproducing the most subtle image attributes including translucent objects 
such as smoke and water, filmy fabrics, and, importantly, the edge blur of 
rapidly moving objects in the scene, as well as shadows. Such attributes 
were relatively much harder to render in photochemical optical composites, 
though by no means impossible, when a highly skilled practitioner of the 
art was involved. 
The most significant issues noted above are those of "motion blur" and 
"shadows." In these situations the compositing system will be combining 
proportions of both foreground and background portions of the scene 
together. It is desirable that a shadow cast by the foreground scene onto 
the background matte field will retain enough image density to record in 
the Alpha channel, or matte, as a smooth quiet signal. The same is true 
for the reduced background signal occurring in the area of "motion blur" 
when a rapidly moving portion of the foreground subject is partially, 
though not completely, obscuring the background matte field. A great deal 
of filmed traveling matte footage is to transferred to video via a 
telecine device, the leading such device in the industry being the Rank 
Telecine. This is essentially a flying spot scanner device employing a CRT 
source together with optics, such that a film image frame is scanned by 
the CRT "spot" whereby each pixel is coded into its component parts and 
stored as data. The device is handicapped by the fact that the CRT 
phosphors employed are essentially green in color, requiring excessive 
amplification of the relatively weak signal derived from the blue record 
of film. Thus the relative grainy record of Tungsten balanced negative 
film is exacerbated by the excessive electronic amplification resulting in 
what is termed "noisy" mattes. Quite obviously, deriving a matte signal 
from the fine grain green record of the same film illuminated by an 
essentially green phosphor CRT tube will produce an electronically very 
"quiet" matte. 
Another, small advantage of matting on the green record is derived from the 
fact that the optics of the camera are designed mainly around the green 
portion of the spectrum and, assuming the camera has been properly 
focussed, the very best focus will occur for the green record, with very 
deep red objects suffering slightly by comparison. 
Further discussion on the relative merits of Blue versus Green may be found 
in Ultimatte Technical Bulletin No. 2, "Green or Blue--Selecting a Backing 
Color for an Ultimatte Composite." (Published by the Ultimatte 
Corporation, manufacturer of Petro Vlahos' inventions previously referred 
to.) After a discussion of the many complex issues, the bulletin 
concludes, "There are no simple rules for specifying when to use a blue or 
green backing. Each situation must be analyzed to see whether a blue or a 
green backing will yield better results." 
Among the simplest of techniques for achieving a bluescreen element is that 
of deploying a fabric backing of the appropriate chrominance and luminance 
and staging the scene before it. This, indeed, has been one of the 
principal methods employed for several years. When it is possible to 
isolate the lighting of the backing from the lighting of the foreground 
scene, it is possible to achieve excellent results. The author's 
developments of fluorescent light sources specific to the task (as cited 
in the ASC Manual, p. 435) and those of others in the field have greatly 
improved the results obtained by this approach. However, it is 
increasingly desirable to be able to place the foreground action directly 
in, or on, the backing. In this situation the same light will, of 
necessity, light both the backing and the foreground action. As the 
discussion on page 436 of the ASC Manual illustrates, the existing 
techniques employing fabrics of the prior art are far from effective. 
Painted backings and floors have yielded better results, as these have 
been possible to endow with enhanced properties versus fabric. The 
greatest success in this approach has been the employment of fluorescent 
pigments incorporated in both opaque and transparent paints, (some aspects 
of this discussion are described in U.S. Pat. No. 4,417,791), as these 
permit greater chromatic actinic stimulus for photographic film than do 
conventional pigments. 
However, painted backings suffer the disadvantage of the relatively high 
cost of providing an appropriate substrate, the very high cost of the 
pigments required and the labor to apply them, as well as the inordinate 
time required for the whole operation. To obtain the efficacy of high 
quality painted backings with the simplicity, speed and economy of fabric 
backings requires the development of a new type of dyed fabric backing. 
SUMMARY OF THE INVENTION 
The present invention provides an improved backing screen having particular 
application for use in composite photography. In particular, the present 
invention relates to color difference composite photography, whether 
still, motion picture, video, solid state digital electronic or 
electrophotographic imaging, in which foreground and background scenes are 
separately recorded and subsequently combined using known "blue screen" or 
special color background techniques to form a single image. The present 
invention includes a biaxially stretchable fabric of synthetic fibers 
treated with a dye formulation, including fluorescence which is reactive 
to the visible spectrum, to achieve any of a variety of specific spectral 
loci and luminances, for the purpose of providing a precise chromatic 
actinic stimulus response for a silver halide photographic film, or 
similar response for electronic imaging devices. 
The selected backing is deployed in a support such that the fabric is 
stretched to a smooth, featureless surface and then illuminated. 
Foreground subject matter interposed between the camera and the backing or 
directly on the backing win therefore be readily distinguished and 
"matted" for compositing by methods well known to the art. 
In a further aspect of the present invention, the light emitting 
characteristics of the fluorescent matte fabric of the present invention 
may be advantageously relied upon to obtain the desired lighting effect 
in, for example, underwater photography. In yet another embodiment of the 
present invention, the matte fabric of the present invention may be 
configured to cover objects or parts of a person in a field of view. 
FIG. 1 illustrates a C.I.E. (1931) chart showing the chromaticity 
coordinates of the various optimal spectral loci of matte backings of the 
present invention. 
FIG. 2 illustrates several sets of bar graphs corresponding to the optical 
densities in the negative above D-min of Red, Green and Blue for Red, 
Green, Blue, Cyan, Magenta and Yellow loci in FIG. 1. 
FIG. 3A is a diagrammatic view illustrating a matte backing screen of the 
present invention deployed as attached to a frame; FIG. 3B illustrates a 
tie adapted for use to attach the matte backing screen to the frame. 
FIGS. 4A-C are graphs comparing the spectral reflectance of green, red and 
blue matte backings of the present invention and the prior art. 
FIG. 5 is a graph showing the spectral sensitivity curves for Red, Green 
and Blue of a color negative. 
FIG. 6 is a graph comparing the optical densities above D-min for a 
negative exposed using a matte backing of the present invention and an 
industry standard matte backing. 
FIGS. 7A and 7B illustrate the topside and underside view of the overlock 
stitch implemented to joined panels of matte backing in accordance with 
the present invention. 
FIG. 8 illustrates configuring the matte fabric of the present invention to 
be worn on a part of a person. 
FIG. 9 illustrates the set up in which the matte backing of the present 
invention may be deployed to cover a floor. 
FIG. 10 illustrates the use of several matte panels of the present 
invention having different fluorescence characteristics to obtain the 
desired lighting effect in underwater photography. 
FIG. 11 illustrates configuring the matte fabric of the present invention 
to cover objects in a field of view.

DETAILED DESCRIPTION OF THE INVENTION 
A backing screen is disclosed having particular application for use in 
color difference traveling matte composite photography. In particular, the 
present invention relates to composite color photography, whether still, 
motion picture, video or solid state digital electronic imaging in which 
foreground and background scenes are separately recorded and subsequently 
combined, using known "blue screen" or special color background 
techniques, to form a single image. The present invention includes a 
biaxially stretchable fabric treated with a dye formulation, including 
fluorescence, to achieve any of a variety of specific spectral loci and 
luminances for the purpose of providing a precise chromatic actinic 
stimulus response optimal for silver halide photographic film, or similar 
response for electronic imaging devices. 
The optimal spectral loci can be designated as illustrated in FIG. 1 a 
using C.I.E. (Commission Internationale de l'Eclairage) (1931) 2.degree. 
Chromaticity coordinates, with C.I.E. Illuminant D65 as a reference, as 
follows (for additional discussion on C.I.E. standards, references are 
made to "Handbook of Colorimetry", prepared by Color Measurement 
Laboratory at Massachusetts Institute of Technology under the direction of 
Arthur C. Hardy, published by Technology Press, MIT (1936); and "Color 
Measurement--Theme and Variations" by D. L. MacAdam, Second Revised 
Edition, (1985): 
Red locus 1 of FIG. 1 is represented as a circular area with a focal point 
located at coordinates x=0.6300 and y=0.3450 and with a radius of 0.06 of 
the C.I.E. scale, a dominant wavelength of 605 n.m., a purity of at least 
80% and a luminance greater than 58%. When exposed to EC 5293 under Kodak 
LAD "laboratory aim density" standard conditions, a backing having these 
color characteristics produces densities (in accordance with ANSI/ISO May 
3, 1984 Standards) in the negative above D-min of Red: 106; Green: 37; 
Blue: 35, as illustrated by graph 7 of FIG. 2. 
Green locus 2 of FIG. 2 is represented as a circular area with a focal 
point located at chromaticity coordinates x=0.2850 and y=0.6100, having a 
radius of 0.06 of the C.I.E. scale, a dominant wavelength of 547 n.m., a 
purity of at least 60% and a luminance greater than 78%. When exposed to 
EC 5293 under Kodak LAD standard conditions, a backing having these color 
characteristics typically produces densities in the negative above D-min 
of Red: 57; Green: 120; Blue: 50, as illustrated by graph 0 of FIG. 2. 
Blue locus 3 of FIG. 1 is represented as a circular area with a focal point 
located at chromaticity coordinates x=0.1650 and y=0.0800; having a radius 
of 0.06 of the C.I.E. scale; a dominant wavelength of 462 n.m.; a purity 
of at least 70%; and a luminance greater than 10%. When exposed to EC 
5293, under Kodak LAD standard conditions a backing having these color 
characteristics produces densities in the negative above D-min of Red: 31; 
Green: 53; Blue: 93, as illustrated by graph 9 in FIG. 2. 
Cyan locus 4 of FIG. 1 is represented as a circular area with a focal point 
located at chromaticity coordinates x=0.1750 and y=0.3000; a radius of 
0.06 of the C.I.E. scale; a dominant wavelength of 488 n.m.; a purity of 
at least 25%; and a luminance greater than 30%. When exposed to EC 5293 
under Kodak LAD standard conditions, a backing having these color 
characteristics produces densities in the negative above D-min of Red: 34; 
Green: 83; Blue: 83, as illustrated by graph 10 of FIG. 2. 
Magenta locus 5 of FIG. 1 is represented as a circular area with a focal 
point located at chromaticity coordinates x=0.2700 and y=0.1150; a radius 
of 0.06 of the C.I.E. scale; a dominant wavelength of 560 n.m.; a purity 
of at least 52%; and a luminance greater than 25%. When exposed to EC 5293 
under Kodak LAD standard conditions, a backing having these color 
characteristics produces densities in the negative above D-min of Red: 54; 
Green: 22; Blue: 58, as illustrated by graph 11 in FIG. 2. 
Yellow locus 6 of FIG. 2 is represented as a circular area with a focal 
point located at chromaticity coordinates x=0.4750 and y=0.4400; a radius 
of 0.06 of the C.I.E. scale, a dominant wavelength of 582 n.m.; a purity 
of at least 60%; and a luminance greater than 80%. When exposed to EC 5293 
under Kodak LAD standard conditions, a backing having these color 
characteristics produces densities in the negative above D-min of Red: 95; 
Green: 90; Blue: 38, as illustrated by graph 12 in FIG. 2. 
It is noted that the values of the negative densities noted above are 
intended to demonstrate the relative densities between red, green and blue 
components. Deviations from the noted values should not affect the present 
invention, as long as the relative densities are substantially within the 
same order of magnitude without departing from the scope and spirit of the 
present invention. 
The selected backing is deployed in a support such that the fabric is 
stretched to a smooth, featureless surface and is then illuminated. 
Foreground subject matter interposed between the camera and the backing or 
directly on the backing will therefore be readily distinguished and 
"matted" for compositing by methods well known to the art. Such methods 
include, but are not limited to, those identified in the Background 
section herein, which are fully incorporated by reference herein. In 
particular, without limitation, the matte process disclosed in Petro 
Vlahos' U.S. Pat. Nos. 3,595,987; 4,007,487; 4,100,569; 4,344,085; 
4,409,611; 4,589,013; and 4,625,231, and the U.S. Pat. Nos. 4,417,791; 
4,548,470 and 4,629,298 issued to the inventor of the present invention 
are fully incorporated by reference herein. Given the teachings of the 
present invention, one skilled in the art can implement these methods 
using the matte fabric and dye disclosed herein. 
It is noted that for the Cyan, Magenta and Yellow (complementary colors) 
matte backings of the present invention, the matte process of the prior 
art would need to be inverted. More particularly, with Yellow (inverse of 
Blue) logic, the raw matte is a greyscale image whose value at each point 
is simply the amount by which Blue is lower than the lower of the other 
two colors. The result is a matte which is dead black anywhere Blue is 
more than Red or Green and some shade of grey wherever Blue is the lowest 
primary color. With Magenta logic the raw matte is a greyscale image whose 
value at each point is simply the amount by which Green is lower than the 
lower of the other two colors. The result is a matte which is dead black 
anywhere Green is lower than Red or Blue and some shade of grey wherever 
Green is the lowest primary color. With Cyan logic the raw matte is a 
greyscale image whose value at each point is simply the amount by which 
Red is lower than the lower of the other two colors. The result is a matte 
which is dead black anywhere Red is more than Blue or Green and some shade 
of grey wherever Red is the lowest primary color. 
Referring now to FIG. 3A, a fabric backing screen assembly 60 is 
illustrated. The fabric screen 13 is comprised, in a preferred embodiment, 
of a fabric known to the textile industry as a biaxially stretchable 
material consisting of approximately 90% nylon fiber at from 40 to 70 
denier (a unit of fineness for silk, rayon or nylon yarn equal to the 
fineness of a yarn weighing one gram for each 9000 meters), and 
approximately 10% DuPont "Spandex" fiber at about 250-300 denier, the 
average weight being in the range of 6 to 12 ozs. per sq. yard. One 
example of such a fabric is manufactured by Darlington Mills and 
designated as Style 8050. 
Ties 61 comprising lightweight cotton cords 2, of approximately eighteen 
inches in length are attached to the borders of the fabric screen 3 at 
intervals of approximately seven inches by "garter snaps" 15 (see also 
FIG. 33). These ties 61 permit the screen 13 to be stretched into a 
suitable frame 62 which may be of an aluminum tubular design, wood, or the 
like. Once so deployed, the screen 13 exhibits an extremely smooth, flat, 
wrinkle-free surface, providing for a featureless image when photographed. 
The use of this method of attachment avoids the conventional requirement 
for a hem in which are installed grommets to permit tying with cord. The 
rationale for this novel approach is that the stretchability of the fabric 
panel is not compromised by the hemming and grommetting operation, and 
further, that the ties can be readily detached from the fabric to permit 
laundering the fabric panel. 
To achieve the high chrominance and high luminance desired for optimal 
matte performance, the fabric of the present invention is treated with 
specific dyes as required to provide either Red, Green, Blue, Cyan, 
Magenta or Yellow loci having the characteristics previously described in 
conjunction with FIG. 1. These dyes employ fluorescence as the mechanism 
by which to achieve the enhanced chrominance and luminance as specified. 
In particular, they employ a class of fluorescent dyes known as 
daylight-fluorescence which are capable of excitation by a broad spectrum 
of radiation from ultraviolet into the visible region. Thus, the need for 
supplemental filtered light specific to the backing screen is reduced or 
eliminated by the conversion mechanism of fluorescence whereby radiation 
of undesirable shorter wavelengths are absorbed and converted to the 
desired wavelength; i.e. blue and green light can be absorbed, converted 
and re-emitted as red light. For a more detailed background discussion 
relating to fluorescent materials, reference is made to the chapter on 
"Luminescent Materials (Fluorescent Daylight)" by Richard A Ward and 
Edward L. Kimmel, published in Kirk-Othmer: Encyclopedia of Chemical 
Technology, Vol. 14, 3rd Edition (1981). Further, U.S. Pat. Nos. 
1,836,529; 2,417,384; 2,498,592 and 3,014,041, for examples, are 
instructional regarding fluorescent materials. Further reference is made 
to "The `Day-Glo` Daylight Fluorescent Color Specification System" by 
Richard A. Ward of Switzer Brothers, Inc., Cleveland, Ohio (1952). The 
discussions in the aforementioned references set forth the state of the 
art in fluorescent materials, and they will not be repeated herein so as 
not to obscure the understanding of the present invention, but are instead 
fully incorporated by reference herein. 
There are relatively few such fluorescent dyes to choose from, and these 
have to be manipulated in specific ways in order to produce the desired 
result. The effective phosphor for the green dye, for example, is actually 
the greenish-yellow coumarin dye Alberta Yellow (Solvent Yellow 135) with 
a dominant emission of 563.2 n.m. However it has strong emission from 530 
n.m. through 560 n.m. It is therefore attenuated with the addition of a 
small amount (on the order of 2-6%) of phthalocyanine green dye which acts 
as an absorption filter to suppress the longer wavelengths below 560 n.m., 
yielding C.I.E. data as follows: x=0.2843, y=0.5676, a dominant wavelength 
of 545 nm.; and at least a luminance of 75%; and a purity of 60.32%. 
It is noted that the specific resultant luminance peak (green in the 
foregoing example) becomes better defined as more absorption agent is 
added, but the overall luminance intensity may be decreased if too much 
absorption agent is added as the absorption agent inevitably also absorbs 
part of the source illuminant. It is therefore necessary to empirically 
adjust the amount of absorption agent to obtain the desired chrominance 
and luminance requirements. Given the disclosure of the present invention 
herein, it would not be difficult for one skilled in the art to accomplish 
this task without undue experimentation. 
When illuminated by C.I.E. Standard Illuminant D65 (i.e. a daylight 
reference), an optimal exposure is recorded on motion picture film (or 
other recording device) in which the backing screen records as one and a 
half "stops" greater than a standard 18% photographic grey card 
illuminated by the same source. (A photographic "stop" represents a 
measure of the actinic speed of the photographic process, where the quanta 
of actinic radiation is doubled for each progressively larger stop. The 
speed of the photographic process can be affected by altering the quanta 
of radiation at the subject, the aperture of the lens at the camera, or 
the actinic sensitivity of the film or other sensor.) When read in a 
densitometer, the developed negative will typically show readings (above 
minimum density or D-Min) of Red: 58; Green: 120; and Blue: 50 and display 
the spectral reflectance traces shown in FIG. 4A, curve 16a. (It is noted 
that the traces shown in FIGS. 6A-C were obtained using illumination of 
"HMI" movie stage artificial daylight condition. While this HMI 
illumination is slightly different from the D65 Illuminant, FIGS. 4A-C 
nonetheless illustrate the relative reflectance between the matte backings 
of the present invention and the prior art which are similar to traces 
otherwise obtained using D65 illumination.) 
For comparison, the industry standard green fabric screen (i.e. "Tempo") 
analyzed under identical circumstances yields the following C.I.E. data: 
x=0.2874, y=0.5199; a dominant wavelength of 544.1 nm.; a luminance of 
28.8%; and a purity of 47.61%. When illuminated by C.I.E. Standard 
Illuminant D165 (i.e. daylight), the industry standard fabric records as 
one half stop lower than a standard 18% photographic grey card illuminated 
by the same source. When read in a densitometer, the developed negative 
will typically show readings (above D-Min) of Red: 41; Green: 79; and 
Blue: 37, and display the spectral reflectance traces shown in FIG. 4A, 
curve 17a. Thus the backing screen of the present invention yields a 
substantial improvement in terms of density and color separation in the 
developed negative, and consequently greatly facilitates the processing of 
the matte signals. A very significant attribute of the present invention 
is that the two stop increase in photographic "speed" described above can 
quite readily translate into a reduction of seventy-five percent of the 
lighting apparatus normally required. The provision and operation of such 
apparatus constitutes a major expense in motion picture production, and 
reductions on scale of seventy-five percent result in very substantial 
savings. 
For the Red screen version, a further manipulation is affected which 
exploits the ability to transfer energy from one fluorescent dye to 
another. Thus, the Alberta Yellow dye has added to it Rhodamine F5G 
(normally a "salmon" or slightly magenta orange). The result is that the 
emission from the Alberta Yellow is reabsorbed by the Rhodamine and added 
to the excitation already occurring by the Standard illuminant. However, 
the Alberta Yellow is meanwhile absorbing the blue violet component of the 
Rhodamine emission, thus canceling it from the total emission and adding 
it to the orange component. 
To this arrangement, still another dye is introduced: Rhodamine B (Basic 
Violet 10) is normally, as its name suggests, a violet color with deep red 
and deep blue-violet components. The result is that the Rhodamine B now 
absorbs the emission of the previous combination again, in addition to 
that of the Standard Illuminant, while simultaneously having its 
blue-violet component absorbed and re-emitted in the 600 n.m. region (or 
red). All of these conversion and reconversion give rise to a cascading 
fluorescence effect which result in a very efficient emitter of red 
illumination having the appearance of being internally powered as in an 
electro-luminescent device. 
The spectral reflectance traces for the Red screen of the present invention 
(16b) and the prior art Red screen (17b) are shown in FIG. 4B. 
For the Blue version, relatively less assistance is required from 
fluorescence, as an excessively high luminance in a Blue traveling matte 
backing will cause a phenomena known as "cyan undercut" which is believed 
to result from an interaction between the various emulsion layers 
comprising the color film and which expresses itself as a red fringing 
around foreground object details. An optimal Blue backing luminance is 
achieved at par with that of an 18% photographic grey card illuminated by 
the Standard Illuminant. 
The spectral reflectance traces for the Blue screen of the present 
invention (16c) and the prior art Blue screen (17c) are shown in FIG. 4C. 
Given the discussions above, similar processes may be undertaken to obtain 
the other color versions. 
It is noted that the exact composition of the fluorescent dye may vary from 
batch to batch of the matte fabric dyed. Given the color and luminance 
requirements for a specific matte procedure and the state of the art in 
fluorescent dye, those skilled in the art will recognize from the 
foregoing description how to adjust the formulation of the dye mixtures to 
meet the desired chrominance and luminance requirements without undue 
experimentation. 
The fabric is colored to achieve one of the previously described optimal 
chroma (color) and luminance (brightness) specifications by methods known 
to the textile dying industry as "total exhaust dying," representative of 
which is the following procedure from Yorkshire Pat-Chem, Inc.: 
ROTARY DYE MACHINES GARMENT DYEING PROCEDURE FOR FLUORESCENT PIGMENTS 
Record owf--dry weight of material to be dyed. 
1. Set bath at 80.degree. F. (approximately). 
2. Add 0.25% owf* nonionic surfactant, low foamer preferred. 
3. Heat to 180.degree. F. and run for 10 minutes. 
4. Drop and rinse at 80.degree. F. for 2 minutes, drop. 
5. Refill at 80.degree.. 
6. Add 4% owf diluted Pretreat SS-10 and run 5 minutes (while machine is in 
motion). 
7. Heat to 140.degree. F. and run 10 minutes. 
8. Drop and rinse at 80.degree. F. for two minutes. 
9. Refill at 80.degree. F. and add well-diluted dye slowly (while machine 
is in motion). 
10. Run 5 minutes, begin heating to 160.degree. F. (3-4/minute). 
11. Run 10 minutes at 160.degree. F. 
12. Slowly add 0.5 to 1.0% owf acetic acid (well-diluted) and run an 
additional 10 minutes. Dye bath should be practically clear; if not, add 
additional acetic and run 5 to 10 minutes longer. 
13. Drop and refill at 80.degree. F. 
14. Add 8% Aftertreat SS-30 (diluted) and heat to 120.degree. F. 
15. Run 10 minutes. Softener may be added halfway through this cycle. 
16. Drop and rinse at 80.degree. F. for 2 minutes. 
17. Drop, extract, and tumble dry. 
*Amount will vary according to strength of surfactant. 
NOTE: For best results, liquor ratios should not be greater than 20:1 nor 
less than 15:1 in weight. 
In accordance with the process of traveling matte photography, the backing 
screen is photographed with a photographic film such as Eastman Kodak 
color negative EC 5293 having spectral sensitivity curves for Red (curve 
50), Green (curve 51) and Blue (curve 52) illustrated in FIG. 5. The 
developed negative subsequently exhibits above D-min values illustrated in 
FIG. 6, graph 8. By comparison, the industry standard backing material, 
"Tempo" Green, having the spectral reflectance trace illustrated in FIG. 
4A, curve 17a, when photographed with Eastman Kodak color negative film 
5293 of ilustration FIG. 5 the developed negative exhibits above D-min 
values illustrated in FIG. 6, graph 18. 
Referring to FIGS. 7A and 7B, the matte fabric, which is produced as an 
eight foot wide bolt, is sewn into large panels 65, 67 as required, by 
methods known to the textile industry and, in one preferred embodiment, 
utilizing an overlock sewing machine. The stitch 66 thus obtained retains 
the stretchable capability in the seamed fabric. The threads used should 
be dyed with the same dye used for the panels. 
The fabric panel is then mounted into a rigid frame of the type commonly 
used in the motion picture and photographic industries and usually 
constructed of tubular aluminum in a square or rectangular configuration. 
In the preferred embodiment, the frame provided is approximately 10% 
larger than the fabric panel to permit the fabric to be stretched to a 
taught, flat and wrinkle free condition. 
Referring now to FIG. 8, another embodiment is illustrated in which the 
matte fabric is sewn into a form fitting garment 68 (in this case for a 
human head) whereby the wearer may be "matted." 
Daylight performance: 
A major difficulty is encountered when attempting to produce traveling 
matte elements in natural daylight with conventional backing materials, 
since the backing illumination and the foreground illumination are of the 
same source and intensity. The conventional materials currently in use 
provide too low a reflectance, together with insufficient chrominance, to 
produce an optimum exposure in the matte field. The situation is 
exacerbated if it is also desired to hold shadows in the matte field, as 
these will be two or more stops lower in intensity than the "key" lit 
areas. The matte signal produced is then dangerously weak and requires 
greater amplification. This combined with the increased grain of the 
reduced exposure results in a "noisy" matte signal. The traditional 
solution has been to provide either additional lighting for the backing or 
to reduce the light on the foreground subject by rigging "silks" or other 
light attenuating materials, in either case adding time and expense to the 
whole procedure. The two stop advantage provided by the present invention 
provides for clean, quiet matte signals in both the key lit and shadow 
areas of the matte field. 
Floor (or limbo) mattes: 
Problems similar to the day exterior situation above described are 
encountered for floor, or limbo mattes. This entails matting a subject 
actually standing on, or otherwise in contact with the backing material. 
Here again both the backing and the subject will be lit to the same value, 
and the conventional material's insufficient reflectance values will 
create the problems as described above for the daylight exterior 
circumstance. FIG. 9 illustrates the present invention deployed as a 
vertical backing screen 13 coved onto the stage floor so as to provide a 
"limbo" backing. Sandbags 24 secure the perimeter of that section of the 
screen 13 that covers the floor. If the sandbags 24 will be in the field 
of view (e.g., with the sandbags positioned on the screen 13), they are 
covered with the matte fabric of the present invention. 
Underwater performance: 
In another embodiment, the unique properties of the fluorescent dyed fabric 
of the present invention can be exploited to provide effective means for 
underwater traveling matte photography. One of the central problems in 
underwater photography is that the longer wavelengths of light (and to a 
lesser extent the short) are absorbed in water at a far greater rate than 
are the medium wavelengths. Thus cyan light transmits quite well, while 
red light is absorbed to a severe degree with violet affected also. One 
skilled in the art is familiar with the photographic result of this 
function in the overall bluish green appearance of underwater photography. 
(An excellent paper on this subject by Tuckerman Biays is to be found in 
the S.M.P.T.E. Journal, Vol. 94, No. 3, March 1985.) The present invention 
solves much of this problem by exploiting the energy conversion properties 
of fluorescent dyes. A greenscreen 13 of the present invention, as 
illustrated in FIG. 10, will absorb cyan light and re-emit it as green 
light. Additionally, redscreens 19 of the present invention can be 
employed as reflectors to enhance the red component of the light 
illuminating the foreground subject 20. Thus, white light 21 entering the 
tank 22 of water from above the water is progressively deprived of its red 
component by absorption by the water in the tank until it reaches the red 
screen material. The now predominantly blue-green light is then absorbed 
by the fluorescent dyes in the redscreen 19 and converted to red light. 
The emitted red light is, of course, attenuated to some degree en route 
from the screen 19 to the subject 20 and the resultant light reflected 
from the subject to the camera more nearly approaches a normal color 
spectrum. 
Flags: 
Referring now to FIG. 22 yet another embodiment is illustrated, in which 
the backing screens of the present invention can be provided as a slip 
cover for the conventional "flags" used in photography as well as other 
pieces of photographic equipment such as sand bags, light stands and even 
as "sleeves" for cables used for suspending actors or as safety harness. 
Such conventional flags are typically a construction of a steel rod 
framework onto which is usually sewn a black fabric so as to create a 
lightweight flat black panel for obscuring unwanted objects. Ordinarily 
such flags are used to block unwanted light failing into an area in the 
camera's field of view and thus the flag itself would not normally ever be 
seen by the camera. However, in the present invention, the flags 23 are 
intentionally used within the field of view to provide a matting field in 
place of the unwanted object which may be a piece of lighting equipment, 
or a support for an object that will eventually appear to be levitated in 
the air. In the latter case, footage may be acquired during a separate 
"take" in which the background scene only is filmed. Subsequently in 
another take, the object desired to be levitated is placed in the field of 
view and supported as appropriate. The "flag" of matting material is then 
placed between the support structure and the camera such that the 
structure is obscured. In subsequent compositing processes, the "flag" 
generates a matte signal and this is then used to replace the "flag" in 
the image with the corresponding portion of the previously filmed 
background scene. Likewise, referring now to FIG. 8, either portions or an 
entire human body may be covered with a closely form fitting suit 
fabricated of the matte backing material of the present invention, and 
thus said portions or body may be matted out of a scene. Among the effects 
that may be thus achieved would be the appearance of an apparition of 
human form which may be essentially transparent, but yet retains 
sufficient shadow details as to reveal that there is such a form present. 
Or the form may be revealed as a specular reflecting object such as glass 
or water by the expedient of "mapping" reflections of the surrounding 
scene onto such a character by methods known to the computer graphic 
special effect arts. 
Thus a backing screen has been disclosed having particular use in composite 
photography including a biaxially stretchable fabric treated with a dye 
formulation including fluorescence to achieve a specific color space 
coordinate, for the purpose of providing a precise chromatic actinic 
stimulus response for silver halide photographic film, or similar response 
for electronic imaging devices. 
While the present invention has been described with reference to FIGS. 1 
through 11, it should be understood that the figures are for illustration 
only, and should not be taken as limitations on the invention. It is 
contemplated that many changes and modifications may be made by one of 
ordinary skill in the art, to the materials and arrangements of elements 
disclosed without departing from the spirit and scope of the invention. 
For example, films other than EC 5293 and having different spectral 
sensitivities may necessitate shifts in the optimal chrominance 
specifications of the dyes to achieve an optimal exposure. Those of skill 
in the art will recognize from the foregoing description how to derive the 
new optimal specifications. Moreover, those of skill in the fabric dying 
art will recognize from the foregoing description how to derive the new 
optimal specifications. Those of sill in the fabric dying art will be able 
to alter the formulation of the dye mixtures to account for any such 
shifts in the optimal chrominance and luminance specifications.