Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
wo98n~wg1 PCT/CA96/~10
COLOR ~u~E MODE~
~ield of the Invention
This application relates to a physical model for
representing in three dimensions the set of colors repro-
- ducible in a given medium by combining three primary colors
and a base color in various amounts and proportions. The
model enables development of an intuitive understanding of
color theory and facilitates mapping of a selected color
from one color medium (such as a computer color monitor) to
another color medium (such as a photographic slide).
Backqround of the Invention
The concept of a ~color cube" or "color solid~
for representing color in three dimensions is well known.
In a color cube three different primary colorants are
combined in various amounts and proportions with a base
color, such as black or white, to yield a spectrum of
colors. The color cube is arranged so that the three
selected primary colors, such as cyan, magenta and yellow,
are arranged along three mutually perpendicular and inter-
secting edges of the cube. The cube corner where the three
primary colorant edges merge is taken as the base point,
and the amount of each primary will vary from a ml nimt~m at
this base corner to a m~x;~lm at the opposite end of the
respective edge.
The color variation will normally be uniform
along each edge of the cube so that each face of the cube
will represent the spectrum of colors reproducible when one
of the primaries is held constant in either its minimum or
m~i mllm amount and the other two primaries are varied.
Points which lie within the color cube represent colors
obtained by combining variou~ proportions of all three of
the primary colors with the base color. For example, the
diagonal axis joining the opposite white and black corners
of the cube represents shades of grey which may be derived
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wo ~n~ssl PCT/CA~ ~ 10
from combining equal amounts of the three primary colours
with either white or black.
Heretofore, the colour cube concept has been used
as a theoretical model for understanding colour and as a
basis for constructing two dimensional color chart systems.
Such color chart systems typically comprise an ordered
array of two dimensional charts which represent various
subsets of the color cube. For example, two ~lm~n~ional
charts may be derived by passing a series of ~ertical or
horizontal planes through the color cube at various loca-
tions. Such two di~ensional charts are of considerable
value to printers and the like who are frequently called
upon to identify, match and duplicate colors and to choose
complimentary and contrasting colors.
In addition to developing color chart systems
based on parallel, vertical or horizontal sections through
a theoretical color cube, more sophisticated color charts
may be derived by logically dissecting a color cube along
a series of planes perpendicular to a diagonal axis of the
cube, as is described in United States patent No. 4,009,527
Scott et al. issued 1 March, 1977. The advantage of the
Scott system is that all three of the primary colorants are
varied on each of the sequential color charts. Thus all
three of the primary colorants change simultaneously as one
moves from chart to chart in sequence, and the consecutive
charts offer progressively increasing color densities.
United States patent No. 3,751,829 Foss issued 14
August 1973, also discloses a series of color charts based
on the color cube concept. The Foss color charts are
derived by logically dividing the color cube into a series
of concentric and similarly oriented cu~ic volumes. The
charts may be arranged in a variety of ways to provide a
continuous two dimensional representation of the set of
CA 02258774 1998-12-18
. . ...
c~lc~s repr~duc~ie L~om ~omD ~.ing th~ primar~ cclo.-arts _n
di~rerent amo~nts and pr~porticn~.
United Sta~e~ p~te~ ~o. 2,ia4,;25, ~hic~ 1~sued
tc Patter~on cn 13 ~e~e~ber, 1939, re'ates t~ a three-
dime~ onal ~olor demo~straticn apparatus wh1c~. ccnsi~ts c~
~eparable s~ent~. T~Le seg~ents demonstrate the ~ro-
gr2ssion of c~lor intensitie~ ~h~h wou'd be ef~ 'ed b~-
combi~atic~9 o~ dif~erent prlmary cclors. ~h~ P~t'~rso..
C zp~aratus is ~referably s~h~ric~1 in shape and the s~par-
a~le segmencs are derined by div~iding tne sphe_~ i-. verti-
cal ra~i21 planes.
AlthG_gh such colcr chart ~y~tems are -u~er~or to
:~ -onve~tian~' ~c'or ~h'ps and ~olo~ wheei~ a~a;l~ble ~
pa~.t ~,o-es and ~he ~i~e, the~ do ~ot enc~'e ~ user tG
intu~ti~eiy und~rstand c~lcY t'lecry or ~as~ ork witr
colcx in _hree dimensicn~ . o~der r~ se ~ull~ efC~cti~e,
a colar chart or mcdel shoul~ pre~e~ably e~o~y ail ~f t~e
fol]~wing charact_ristics
~ he m~del ~LO~'' d represer.t the e~tll- set of
CO_J--S re~rcducii: le in a ~ en ~ned~ um . ~uc~. cciors
sho~ld be a~rarged i~ oraer~d .ashion so ~h~ the~
ma~r be c~n~er.ien_iY accessec and vi~u~ con~are~
.5 ~.Ji~h~ut iterat- vely fli~Jpi~g ~rom chart to chart .
' ) The mode~ s~cu~a protrl~e a syst~m ~or ~ne~ningf-u~-
l~r describirlg 2ver~ oo;or withi.n the oolor set.
( 3 ) The rr!odel s~1auld ndic;~te how to reprod~ a
s~olected coior ln the given m~diu~ ~y cotnbinin~ on- cr
_ ~ ~nore primary cclcr~ ard ~ase cGl~r for that rr.ediu~ .
he rnodel s~ouid f~cllitate ~r.app ~g cf a selected
~o_or f ~-o~r. one :nediutr. I~ suc~. as a c~mputex s~olor
mcnitor) to ~nother r..edlum ( such as a photograFhi~
s ~ la~ ) .~~ Althoug~. conventiona' two ~ime~sional cclor cha~~ syste~s
usef~l for many pur~ose~, t;~ey are not c~=pable o-
~a~ isf~,~irg ~ll cf t~e ~ove requ ' reme~t3 . T.~e need has
~D~o C~
CA 02258774 1998-12-18
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t~ere~re ari.~n fc~ a ~hree dim~nsional phy~;ical rr.ode~
~ased on the cclor cu}: e concept ~Jr.lcn may be er!n~loyed as a
tco' for chaosi~g colors, ~escr ~ing color,5, reprcd~cing
co1 ors, ar~d m~pping colcr,s ~et~reen di~erent c~lor media.
AMEND~D SHEET
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WO98/0~91 PCT/CA96~510
Summary of the Invention
In accordance with the invention, a cuboidal
physical model for representing a set of colors reproduc-
ible in a given medium by combining three primary colors
and a base color is disclosed. The model has first, second
and third coordinate axes having a common origin and
includes a plurality of spaced-apart elongate members each
extending along an axis parallel to one of the coordinate
axes. The model further includes a plurality of discrete
elements slidably connectable to the elongate members, each
element having a color derived by combining one or more of
the primary colors and a base color in selected propor-
tions. Each element has a designated spacial positionwithin the model relative to the origin.
The first, second and third axes each preferably
represent relative amounts of one of the primary colors.
Each of the discrete elements represents the particular
color derived by combining the base and primary colors in
proportions defined by the orientation of the element
relative to the origin.
Preferably the particular color of each discrete
elements is applied to an exterior surface thereof. For
example, each discrete element may consist of a cube-shaped
block and the particular color for that element may be
applied to the exterior surfaces of the block.
The model is preferably comprised of X3 discrete
elements, where X is greater than or equal to two. Prefer-
ably, each of the discrete elements has a unique identifier
marked thereon representative of the elementJs designated
spacial position within the cube. The unique identifier
for each of the elements preferably comprises an alpha-
numeric code representative of the proportions of the
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primary colors combined to yield the element's particular
color.
Each of the discrete elements preferably includes
- 5 mutually perpendicular first, second and third apertures
extending therethrough for slidably receiving the elongate
members. The apertures may be intersecting or non-inter-
secting. In one embodiment of the invention, the elongate
rods may be flexible. Spacers may be mounted on the
elongate members between the discrete elements for biasing
the elements toward their designated spacial position.
Fasteners releasably connectable to end portions of the
elongate members may also be provided for preventing
unintentional disassembly of the model.
A color mapping tool is also disclosed for
mapping selected colors between first and second color
media. The mapping tool includes a first model as de-
scribed above representing the set of colors reproducible
in a first medium by combining a first set of primary
colors and a base color in selected proportions; and a
second model as described above representing the set of
colors reproducible in a second medium by combining a
second set of primary colors and a base color in selected
proportions. Each of the discrete elements in the first
model preferably bears a first mapping identifier represen-
tative of the coordinate position of a discrete element in
the second model having a color corresponding to the the
first model discrete element.
Preferably the first mapping identifier includes
an alphanumeric code representative of the relative propor-
tions of the second set of primary colors combined to yield
the color in the second medium.
A method of mapping a selected color from a first
color medium to a second color medium is also disclosed
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WO ~891 PCT/CA~ ~,lO
which includes the steps of providing a color mapping tool
as described above; identifying the discrete element in the
first model bearing a color which most closely matches the
selected color; referring to the first ~apping identifier
on the ~irst model discrete element to identify the coordi-
nate position of a discrete element in the second color
medium having a color corresponding to the selected color;
and reproducing the selected color in the second color
medium by referring the to unique the identifier on the
second model discrete element.
A kit for for~ing a cuboidal model representative
of a set of colors reproducible in a given medium by
combining three primary colors and a base color is also
disclosed. The kit comprises a plurality of elongate
members and a plurality of discrete elements slidably
connectable to said elongate members. Each of the discrete
elements has a distinct color derived by combining one or
more of the primary colors and base color in selected
proportions and a unique identifier representative of the
elements preferred spacial position within the model
relative to the other elements.
Brief Description of the Drawings
In drawings which illustrate embodiments of the
invention,
Figure 1 is a perspective, diagrammatic view of
a color cube with the primary colorants yellow, magenta and
cyan arranged along three mutually perpendicular and
intersecting edges thereof;
Figure 2 is a perspective, diagrammatic view of
a color cube with the primary colorants red, green and blue
arranged along three mutually perpendicular and intersect-
ing edges thereof;
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WO 98/04891 PCT/C~96tO0510
Figure 3 is an isometric, partially exploded view
of a model constructed in accordance with the invention;
Figure 4 is an isometric view of the model of
- 5 Figure 3 in a partially disassembled configurationi
Figure 5(a) is a front elevational view of one of
the discrete elements comprising the model of Figure 3;
Figure 5(b) is a top, plan view of the discrete
element of Figure 5(a);
Figure 5(c) is a left side elevational view of
the discrete element of Figure 5(a);
Figure 5(d) is a cross-sectional view of the
discrete element of Figure 5(a); and
Figure 6 is a diagrammatic view illustrating a
method of mapping a selected color from one medium to
another medium utilizing a plurality of color cube models.
Figure 7 is an isometric view of an alternative
embodiment of the invention consisting of a plurality of
block-shaped color elements slidably mounted on rods
arranged to form a three-~m~n~ional cubical matrix;
Figure 8 is an isometric, partially disassembled
view of the model of Figure 7;
Figure 9(a) is a top plan view of one of the
color elements of Figure 7;
Figure 9(b) is a front view of one of the color
elements of Figure 7;
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WO98~891 PCT/CA96/WK10
Figure 9(c) is a right side view of one of the
color elements of Figure 7;
Figure 9(d) is a cross-sectional view of one of
the color elements of Figure 7;
Figure 9(e) is a perspective view of one of the
color elements of Figure 7;
Figure lO(a) is an isometric view of a further
alternative embodiment of the color cube model consisting
of a plurality of block-shaped elements slidably mounted on
flexi~le connecting rods;
Figure lO(b) is an iso~etric, partially disas-
sembled ~iew of a corner portion of the color cube model of
Figure lO(a);
Figure lO(c) is an isometric view of a further
alternative em~odiment of the color cube of Figures lO(a)
and lO(b) including resilient spacers positioned between
adjacent frame elements;
Figure ll(a) is an enlarged view of an end
portion of a rod constructed according to an alternative
embodiment of the invention;
Figure ll(b) is an enlarged view of an end
portion of a rod constructed according to a further alter-
native embodi~ent of the invention;
Figure ll(c) is an enlarged view of an endportion Of a rod constructed according to a still further
alternative embodiment of the invention;
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WO98t~891 PCT/CA96~S10
Figure 12(a) is a front view of an alternative
color element having mutually perpendicular intersecting
apertures;
Figure 12~b) is a cross-sectional view of the
color element of Figure 12(a); and
Figure 12(c) is perspective view of the color
element of Figure 12(a).
Detailed Description of the Preferred Embodiment
It is well known that a geometric ordering known
as a "color cube" or a "color solid~ may be used to repre-
sent the set of colors obtainable by mixing three primarycolors with a base color (i.e. white or black) in various
amounts and proportions. The color cube concept is ordi-
narily used as a basis for constructing two ~im~nsional
color chart systems (i.e. arrays of two ~imensional charts
representing a series of sections through the cube).
As shown in Figure 1, a color cube may be visual-
ized as having three mutually perpendicular coordinate axes
labelled x, y and z which intersect at one corner of the
cube designated as the origin of the coordinate system.
Each coordinate axis represents relative effective amounts
of one of the three primary colorants. For example, if the
color cube is intended to represent the set of colors
obtainable by mixing the primary colors cyan, magenta and
yellow with a white base color or substrate, then the white
base is considered to be the origin of the coordinate
system. The x axis represents increasing amounts of the
primary color yellow, the y axis represents increasing
amounts of the color magenta, and the z axis represents
increasing amounts of the color cyan. Thus the three edges
of the cube corresponding to the x, y and z axes represent
colors obtained when one of the primary colors is added to
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WO98~1 PCT/CA96~0510
- 10 -
the white base with no admixture of any of the other two
primary colors. The three faces of the cube which meet at
the origin represent the set of colors which may be ob-
tained by applying various amounts of two of the primary
colors and the base color without any admixture of the
third primary. For example, point "1~ indicated on Figure
1, being equidistant from both the x (yellow) and y ~ma-
genta) axes, represents the color which is obtainable by
mixing equal amounts of yellow and magenta with the white
base, with no admixture of cyan.
The remaining three faces of the cube represent
the colors obtainable by mixing various proportions of two
of the primary colors while main-taining one of the primary
colors at its maximum effective value. For example, point
ll2ll indicated on Figure 1, represents the color obtainable
by mixing equal amounts of cyan and yellow while maintain-
ing magenta at its m~ effective value.
Points which lie within the color cube represent
colors which may be obtained by mixing all three of the
primary colors in various proportions with the white base.
For example, a combination of equal proportions of the
three primary colors with the white base yields the color
grey.
The eight corners of a color cube are of special
significance: two opposite corners of the cube are black
and white, representing mi nimtlm and ~iml~m amounts,
respectively, of the three primary colors, cyan, magenta
and yellow; the three corners which lie at the ends of the
x, y and z axes furthest from the origin represent the
three primary colorants in their maximum effective form
without inclusion of any other colorants; and the three
remaining corners represent the colors red, green and blue
which are obtained by mixture of maximally effective
amounts of two of the primary colorants only (i.e. red is
CA 022~8774 1998-12-18
Wo ~91 PCTtCA961~S10
obtained by mixing equal maximally effective amounts of
yellow and magenta with no cyan, etc).
The "CMY coordinate system" described above
(based on the primary colors cyan, magenta and yellow in
combination with a white base), is typically used when
mixing colors for printing or painting. Cyan, magenta and
yellow are sometimes referred to as 'Isubtractive" primary
colors since, when mixed together in maximally effective
amounts, they yield the color black. The term "subtrac-
tive~' stems from the fact that a given pigment reflects
light of a given wavelength or color, and absorbs all
others. White light is known to contain all the colors of
the spectrum. Where the three primary colors cyan, magenta
and yellow are mixed together in relatively equal propor-
tions, very little light is reflected back to the viewer
and the resultant color appears dark.
As shown in Figure 2, the orientation of the
color cube may be easily rotated so that black is the base
color, designated as the origin of the coordinate system,
and the x, y and z axes represent relative amounts of the
primary colors red, green and blue respectively. Red,
green and blue are sometimes referred to as "additive"
primaries since they yield the color white when mixed
together in maximally effective proportions. The term
"additive" stems from the fact that the human eye perceives
red, green and blue light mixed together at maximal inten-
sity as white. The "RGB coordinate system" (based on the
primary colors _ed, ~reen and blue) is used as a means for
describing color as displayed on color television sets,
computer monitors and the like.
Heretofore, the color cube concept has served as
a useful theoretical tool for understanding color theory,
but it has not been widely applied outside of specialized
fields such as the printing trades. One reason why the
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WO98/~wsl PCT/CA~ ~ ~o
~ 12 -
color cube concept has not found wide application in other
fields dealing with the creation and reproduction of color
(such as paint stores, art school courses, fashion design
studios and desk top publishing houses) may be the unavail-
ability of an actual three-dimensional chart or model
embodying the concept in readily understandable terms.
The present invention provides a physical model
10 (Figure 3) for representing the color cube concept in
three dimensions. Model 10 may be manually assembled and
disassembled to facilitate an intuitive understanding of
color theory. As described in further detail below, model
lO may also be employed to assist in mapping a selected
color from one medium (such as a computer monitor) to
another medium (such as a photographic slide).
As shown in Figure 3, model lO consists of a
plurality of discrete elements 12 each preferably having a
separate, distinct color. For example, one of the elements
12 could represent the base color blac~, another the base
color white, and still others the primary colors cyan,
~agenta and yellow. The remaining elements 12 could each
represent one of the set of colors obtainable by mixing
such primary colors and base colors in various amounts and
proportions. The total number of elements 12 comprising
model lo may be described by the formula x3 where "x" is an
integer greater than or equal to 2. For example, if x-10,
model 10 would consist of 1000 discrete elements 12, each
representing a distinct color.
In the preferred embodiment, discrete elements 12
are cubical blocks which may be releasably interconnected
in an ordered fashion to form model 10. As shown best in
Figure 5, each element 12 may include male prongs 16 and
female sockets 18 formed on its external faces. With
reference to Figures 3 - 5, elements 12 may be releasably
coupled together by inserting a male prong 16 projecting
CA 022~8774 1998-12-18
WO9~W91 PCTICA961~510
from one element 12 into a mating socket 18 formed in an
adjacent element }2. Preferably, each element 12 has three
pairs of male prongs 16 and female sockets 18 to enable
interconnection with up to six adjacent elements 12.
As should be readily apparent, other means for
releasably interconnecting discrete elements 12 may be
substituted for mating male and female connectors 16,18.
For example, elements 12 may be releasably connected by
VELCRO~ fasteners or by magnetic attraction. The key
feature is that it must be possible to manipulate model 10
to view its interior elements 12 (which represent colors
derived from combining all three o~ the primary and base
colorants in various proportions). For example, in the
preferred embodiment, the interior elements 12 of model 10
may be visualized by ~nll~lly disassembling the outer el-
ements 12, either in interconnected planar sections (Figure
3) or individually (Figure 4).
Although discrete elements 12 are cubical blocks
in the preferred embodiment, elements of other geometric
shapes may function equally well. In alternative embodi-
ments, discrete elements 12 and releasable connectors 16,18
may be structured to enable disassembly of model 10 in
diagonal as well as vertical or horizontal sections (for
example, along the diagonal grey scale axis extending
between the white and black corner elements 12).
In order for model 10 to function as an accurate
representation of a color cube, elements 12 must be as-
sembled (or reassembled) in the correct order. To thisend, each element 12 has an unique identifier 20 (Figure
5~c)) marked on at least one of its external faces to
indicate the element's preferred spacial position within
model 10. Advantageously, identifier 20 may be an alpha-
numeric code indicative of the preferred coordinate posi-
tion of the particular element 12 relative to the origin of
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Wo98/~91 PCTtCA96/~SlO
a logical coordinate system. For example, if the base
color black is arbitrarily designated as the origin of the
coordinate system, then the logical x, y, and z axes will
represent relative amounts of the primary colors red, green
and blue respectively. The unique identifier 20 for the
black origin is therefore designated by the alphanumeric
code rO bO ~0, each of the digits representing the coord-
inate position of the element 12 relative to the logical x,
y and z axes respectively (and hence the relative amounts
of the primary colorants red, green and blue). Assuming
model 10 consists of 1000 discrete elements 12, the ident-
ifers 20 of each of the corner elements 12 of model 10
would be as set out in the following table:
Color of element 12 Identifier 20
x y z
black (origin) rO gO bO
red rlO gO bO
green rO glO bO
blue rO gO blO
cyan rO glO blO
magenta rlO ~0 blO
yellow rlO glO bO
white rlO glO blO
As well as providing an indication of the pre-
ferred spacial position of a selected element 12 within
model 10, identifier 20 also provides a formula for creat-
ing the distinct color represented by that element 12 from
the three designated primary colorants. For example, an
element 12 having the identifier r7 g4 b6, which represents
a shade of the color pink, may be derived by combining 7
parts red ~35~), 4 parts green (20%) and 6 parts blue (30~)
with 3 parts of the base color black (lS~. The proportion
of the base color to add may be calculated by subtracting
the m~ lm possible effective amount of a primary color
(i.e 10 parts in a model 10 having 1000 discrete elements
12) from the highest actual amount of a base color (i.e. 7
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W098/~891 PCTICA96/~510
- 15 -
parts in the example above) and then converting to percen-
tages.
The same principles would apply if the base color
white is selected as the origin of the coordinate system,
except that each element identifier 20 would represent
relati~e amounts of the primary colors yellow, magenta and
cyan rather than red, green and blue. Assuming, as in the
example above, that model lO consists of lOOO discrete
elements 12, the identifers 20 of each of the corner
elements 12 of model lO in the CMY system would be as set
out in the following table:
Color of element 12 Identifier 20
x y z
black ylO mlO clO
red ylO mlO cO
green ylO mO clO
blue yO mlO clO
20 cyan yO mO clO
magenta yO mlO cO
yellow ylO mO cO
white (origin) yO mO cO
2s If desired, each model element 12 may include
both sets of identifiers 20 described above to facilitate
translation between the RGB coordinate system and the CMY
coordinate system. For example, a user may wish to map a
color image on a computer screen specified in RGB co-
ordinates into a paint medium ordinarily specified in CMY
coordinates. This may be easily accomplished by finding
the element 12 having an identifier 20 matching the RGB co-
ordinates of the color in ~uestion and then rotating the
selected element 12 to note its CMY identifier 20. The
desired color may then be created by mixing the specified
amounts of the primary colorants cyan, magenta, yellow and
base color white rather than red, green, blue and ~ase
color black.
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WO98/~W91 PCT/CA96t~S10
An RGB identifier 20 may be easily converted to
a CMY identifier 20 (and vice versa) according to the
following formula:
% cyan= 100 - ~ red
yellow= 100 - ~ blue
~ magenta=100 - ~ greer.
Ordinarily, model 10 is assigned a standard orientation
(i.e either black origin for the RGB coordinate system or
white origin for the CMY coordinate system) to avoid the
need to mark two separate sets of identifiers 20 on each
model element 12.
Color cube model 10 as described above may be
manually manipulated to elegantly demonstrate various
principles of colour theory. For example, in order to view
what happens to the color set for a particular medium when
the relative amounts of the primary colors are varied, a
user may successively remove planar sections from model 10
after it has been fully assembled. Figure 3 illustrates
how a planar section of interconnected elements 12 may be
removed from the remainder of model 10 to reveal how the
color set would change by reducing the amount of the
primary color green from its maximum effective value.
Similarly, model 10 may be employed to illustrate how the
color set may be darkened by peeling away the three exter-
nal faces meeting at the white origin. Conversely, in
order to lighten the color set, the three external faces
meeting at the black origin could be peeled away. Other
manipulations and comparisons could be made using model 10,
or a series of models 10, to allow the user to visualize
complementary and contrasting colors, grey scale conver-
sions, and adjustments to contrast, hue, tint, colorsaturation and the like.
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Although some of the above color principles may
also be explained using two dimensional color charts, in
practice it would be necessary to iteratively flip from
chart to chart, which is inconvenient and likely to result
in confusion. Model 10 provides a much more intuitive tool
for understanding color theory which can readily be grasped
by casual users
As explained above, the identifier 20 for a given
discrete element 12 speclfies its preferred spacial posi-
tion within model 10 when fully assembled. It is important
to note however, that model 10 need not be assembled in the
preferred ordered fashion. Rather, model 10 may be as-
sembled in any m~n~Pr or order desired to create visually
appealing structures of different shapes and sizes. In
this regard, model 10 may be used by children as a toy or
puzzle rather than a purely utilitarian tool. For example,
each discrete element 12 could be distributed to children
as a cardboard cut-out which may be folded into a cubical
block and assembled by some suitable means to form model
10 .
There are a myriad of other possible applications
for a three-~imensional model 10 having the characteristics
described above. For example, artists, fashion designers,
computer graphics programmers and any other individuals
interested in the creation and reproduction of color could
use model 10 as an instructive tool to visualize, describe
and reproduce colors in different media.
As explained abo~e, the set of colors which may
be represented by model 10 depends upon the medium in
question and the colors which are initially se~lected as the
primary colors. For example, the set of colors which may
be derived by mixing oil paints is slightly different from
the set of colors which may be reproduced on photographic
film, which is different again from the set of colors which
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W098l~91 PCT/CA96/~SiO
may be displayed on a computer monitor. Accordingly,
difficulties often arise when it becomes necessary to
accurately translate color images from one medium to
another.
The primary colors for any particular medium are
ordinarily selected to maximize the set of colors which may
be reproduced in that medium. For example, the luminescent
phosphors used in most computer monitors are not capable of
displaying deep red colors. Consequently, the actual color
red selected as a primary color in the computer monitor
medium is typically different from the red color selected
as a primary color in other media, such as photographic
film. Since the starting primary colors for the two media
are different, the set of colors reproducible by combining
such primary colors in the two media is also different.
This is the root of color translation dif~iculties.
As indicated above, a problem regularly faced by
computer programmers is the need to accurately translate
color images displayed on a computer monitor onto 35 mm
pho~ographic slides. The inventor has determined by
experimentation that it is often necessary to adjust the
color coordinates of the computer image (such as by shift-
ing the image through the chromatic hues and then applyinga contrast and gamma adjustment), before outputting the
image to a 35mm slide. If such image adjustments are not
performed, the colors reproduced on the slide will not
accurately reproduce the color displayed on the monitor.
This discrepancy results since the two color media have
different primary colorants and hence the respective color
coordinate systems do not match on a one to one basis.
The inventor has recognized that translations of
color images from one medium to another could be simplified
considerably by widespread use of customized color cube
models 10 as described above. As shown diagrammatically in
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- 19 -
Figure 6, a ~standard~ or ~hub" model 10 could be defined
to represent the set of colors obtainable by mixing three
generally recognized "stAn~rd" primary colors. Separate
~llocal" models 10', 10ll could be constructed to represent
the set of colors reproducible in particular color media or
environments, such as specific types of paints or printer~s
inks. The "local" models 10l, 10ll for each medium would
differ from the '~st~n~rdll model 10 to the extent that the
primary colors for that medium differed from the ''standard
primary colors.
As shown in Figures 5 and 6, the model 10l for a
particular paint medium would consist of a plurality of
discrete elements 12l each having a ~local~ identifier 20
and a "global" identifier 22. As described abovel local
identifier 20 is a unique alphanumeric code identifying the
preferred coordinate position of the element 12l within the
model 10' for the medium in question. Local identifer 20
also serves the dual purpose of indicating the exact
proportion of primary colors which must be mixed together
to yield the distinct color of the element 121 within such
medium.
Global identifier 22 of a selected element 12l
indicates the coordinate position of the corresponding
element 12 in the standard model 10 having the same color
as the element 12'. ~he values of global identifier 22 are
predetermined based on color matching tests. Global
identifier 22 enables the user to map a selected color from
a particular color medium or environment (such as a com-
puter monitor or photographic slide) to the standard model
10. In order to distinguish global identifier 22 from
local identifer 20, a suitable labelling convention may be
adopted, such as presenting identifier 20 in lower case
letters and identifier 22 in upper case letters (Figures
5(b) and (c)).
CA 02258774 1998-12-18
WO98/~U~1 PCTICA~/~10
- 20 -
Figure 6 illustrates schematically how a standard
color cube model 10 and a pair of local color cube models
0l, 10tl may be used to facilitate mapping of a selected
color between two different color media, namely, paint and
printer's ink. In this example, the standard model 10
comprises 103 discrete elements and the local models 10~,
01l each comprise 63 discrete elements.
Say for example, that a painter wishes to accu-
rately reproduce a particular shade of purple paint usingprinter's ink. Ordinarily, this is a non-trivial task
since the set of colors reproducible in the paint medium
and printer's ink medium are different owing to the differ-
ences between their starting primary colors. However, by
employing three dimensional color cube models lol, 10
representing the set of reproducible colors in each medium,
the color mapping process is simplified considerably.
The first step in the mapping process is to
select the desired color from the local color cube model 10l
corresponding to the paint medium. In the example illus-
trated in Figure 6, the discrete element 12' matching the
selected paint color is located on the upper, external
surface of the model 10l for the paint medium. In practice,
the element 121 matching the desired color may be selected
by visually inspecting model 10' or by using color meters.
In many cases it will be necessary to physically disas-
semble model 10l as described above in order to locate the
particular element 12' matching the desired color.
Once the desired element 121 has been selected,
its local and global identifiers 20, 22 are noted. In the
Figure 6 example, the selected element 12' has a local
identifier 20 designated c3 y3 m6 and a global identifier
designated C4 Y5 M10. As indicated above, global ident-
ifier 22 is distinguishable from local identifier 20 since
CA 02258774 l998-l2-l8
WO9~U~1 PCT/CA961~Sl0
it is presented in upper case rather than lower case
letters. Other suitable labelling conventions may be
adopted.
In order to create the desired color in the paint
medium in question, the user need only refer to the local
identifier 20. In the Figure 6 example, the selected color
may be created in the paint medium by mixing three parts
cyan (25~), 6 parts magenta (50~), and 3 parts yellow (25~)
with no admixture of white base color.
In order to locate the discrete element 12 having
the identical color in the standard model 10, the user
refers to the global identifier 22. As expected, the
discrete element 12 corresponding to the global identifier
22 (C4 Y5 M10) is located on an external face of model 10
when fully assembled (Figure 6).
The next step in the mapping process is to select
the discrete element 121l in the local model 10ll for the
printer's ink medium which has a global identifier 22
~atching the alphanumeric code C4 Y5 M10. In the Figure 6
example, the matching element 12ll has a local identifier 20
designated c4 y3 m6. Thus, in order to reproduce the des-
ired shade of purple in the printer~s ink medium, it is
necessary to mix four parts cyan (30.77~), 3 parts yellow
~23.10~) and 6 parts magenta (46.15~) with no admixture of
base color. In comparing the above mixing formula to the
formula for the same color in the paint medium, it is
apparent that in the printer's ink medium it is necessary
to slightly increase the relative amount of cyan while
slightly reducing the relative amounts of yellow and
magenta in order to yield the same shade of purple. The
above adjustments are required since the shades of cyan,
magenta and yellow which are used as primary colorants in
the printer's ink medium are slightly different from the
primary colors used in the paint medium. As discussed
CA 02258774 1998-12-18
WO98/0~91 PCT/CA~/~Slo
above, primary colors for any given medium are ordinarily
selected to m~im;ze the set of colors reproducible in that
medium, which is in turn determined by the physical prop-
erties of the medium itself.
Although the mapping system described above is
theoretically possible using two ~jmensional color charts
and pre-determined matrix algorithms, the use of three
~im~n.~ional models 10, lol and loll is much more intuitive
and ~eadily understandable. The color mapping system may
be extrapolated to enable mapping between a wide variety of
color media by constructing a series of models 10l, each
representing a distinct color medium. Each of the separate
models 10l could include a global identifier 22 on each
discrete element 12'mapping to the standard or hub model 10.
In order to reproduce a color selected in a "source" medium
in another "destination" medium, the user need only map the
selected source color to the standard or hub model 10 and
then select the corresponding discrete element 121 in the
model 10l for the destination medium. This would completely
avoid the need for a multiplicity of potentially confusing
matrix algorithms to perform the color transforms.
Although the inventor envisages the establishment
of a "standard" or "hub" model 10 to simplify the color
mapping procedure, it is important to recognize that the
selection of a st~n~rd model 10 is entirely arbitrary.
There are no universally recognized "pure" primary colors.
Moreover, color mapping systems employing color models 10l
could be envisaged which do not have any defined standard
whatsoever. For example, with reference to Figure 6, local
model 10l representative of the paint medium could include
a plurality of discrete elements 12l each mapping directly
to corresponding elements 12" in the model 10ll for the
printer's ink medium ~and visa versa), rather than to a
defined standard.
CA 022~8774 1998-12-18
WO98~k~91 PCTICA961~10
Further, each of the so called "local" models 10'
could themselves be the "hub" model for a network of other
models representative of the set of colors reproducible in
other media. In this alternative system, a plurality of
- 5 identifiers 20, 22 could be marked on each discrete element
121 to enable mapping to a plurality of other color cube
models 10l rather than solely to a standard hub model 10.
This mapping system may be conceptualized as a network
having a plurality of interconnected nodes rather than a
plurality of separate nodes each mapping to a standard or
hub node.
As will be apparent to those skilled in the art
in the light of the foregoing disclosure, many alterations
and modifications are possible in the practice of this
invention without departing from the spirit or scope
thereof. For example, although each discrete element 12 of
model 10 is prefera~ly a separate unit having a distinct
color, in an alternative embodiment element 12 may have a
gradation of colors on its external surfaces. In this
embodiment, each element 12 could have a preferred orienta-
tion within model 10. ~or example, the external faces of
element 12 preferably oriented closer to a given primary
color contain slightly more of that primary color than the
opposite faces of the element 12.
Further, each discrete element 12 may itself be
comprised of a plurality of smaller elements which may be
manually assembled or disassembled. Each of the smaller
elements could be assigned slightly different colors so
that the assembled discrete element would represent a
gradation of closely related colors rather than a single
distinct color.
Other equivalent means for arranging elements 12
in a cubic space may also be envisioned. For example, each
element 12 could comprise a light having a distinct color
CA 022~8774 1998-12-18
WO98/~891 PCT/CA96/~510
- Z4 -
when activated. Model lO could comprise a plurality of
such lights arranged in an ordered fashion. The colors of
interior lights could be visualized by switching off the
exterior lights. Thus the interior elements 12 of model
could conceivably be visualized without the need for
physical disassembly of model lO as described in the
embodiments referred to above.
It is important to note that while the entire set
of colors reproducible in a given medium, such as paint or
printer~s ink, may be derived in theory by mixing predeter-
mined primary colors in selected combinations, in practice
non-primary pigments may be used as the mixing colors For
example, in the printer's ink medium, the color black is
often substituted for equal proportions of the primary
colors cyan, magenta and yellow. Printer's cyan and
magenta are relatively expensive and are not always readily
available. Further, these primary colors are transparent
and hence do not provide adequate coverage in some applica-
tions. Accordingly, a selected color which could becreated by mixing ten parts cyan, ten parts magenta and
eighty parts yellow, could optionally be created by mixing
thirty parts black and seventy parts yellow at a much lower
cost.
Similarly, in the paint medium, selected colors
may be created by mixing widely available natural pigments
rather than "pure" primary colors. In such applications,
model lO can continue to be used as a useful tool for
representing in three ~im~n~ions the set of colors repro-
ducible in a given medium. Each discrete element 12 could
optionally bear a supplementary identifier to provide a
formulae for creating the distinct color represented by
such element 12 from a small set of unique colors, such as
naturally occurring pigments, rather than the three stan-
dard primary colors. Of course, such pigments may them-
CA 02258774 1998-12-18
.
W0981~gl PCT/CA96/~Slo
- 2S -
selves be derived by combining the primary colors in
selected combinations.
In a further alternative embodiment illustrated
- ~ in Figures 7-9, model 10 could comprise a plurality of
discrete color elements 12 arranged in a three-~im~n~ional
matrix. For example, elements 12 could be slidably mounted
on rows of spaced rods 24 so that model 10 resembles a
three-dimensional abacus or grid. In this embodiment each
discrete element 12 pre~erably includes three non-inter-
secting apertures 26 extending through element 12 as best
shown in Figures 8 and 9. Each aperture 26 is provided for
snugly receiving a respective rod 24. Accordingly, each
element 12 is ordinarily maintained at its designated
spacial position within model 10 by means of three rods 24
extending in mutually perpendicular axes.
As shown best in Figure 7, the interior elements
12 of model 10 may be readily visualized, while still
maintaining the relative positional relationship between
elements 12, by sliding the exterior elements 12 toward one
side or another of model 10. Thus, in this embodiment the
unique identifier 20 of any selected element 12 may be
easily noted without the need for partial or complete
physical disassembly of model 10.
The Figure 7 embodiment can also be separated
into planar sections of interconnected elements 12, or
individual elements 12, by removing selected rods 24 from
model 10 as shown in Figure 8. For example, any selected
element 12 may be extracted from model 10 by removing the
three rods 24 which pass through that particular element
12. The other elements 12 forming model 10 are maintained
in their designated spacial position by the rP~-n-ng rods
24.
CA 022~8774 1998-12-18
Wos~gl PCTICA~/~S10
Preferably the diameter of apertures 26 is
approximately equal to the diameter of rods 24 so that
elements 12 are held in position by frictional forces.
Rods 24 may be relatively rigid or may be bendable or
resiliently flexible. Bendable rods 24 would allow model
10 to be twisted and contorted into different shapes and
sizes and elastic rods 24 would allow model 10 to be
stretched apart to help simulate color mapping procedures.
Figures lO(a) - lO(c) specifically illustrate an
alternative embodiment of the invention consisting of
flexible rods 24. Rods 24 could consist of flexible wire,
elastics, thread, rope or the like which is threaded
through the apertures 26 formed in frame elements 12. For
example, if rods 24 consist of flaccid threads, the threads
could be knotted at each end to prevent the frame elements
12 from sliding off the ends of model 10. Selected rods 24
(i.e. threads) could be removed from model 10 by untying
the knotted ends and pulling the threads clear of model 10
(Figure lO(b)). Alternatively, removable fasteners could
be secured to the ends of rods 24 as described further
below.
As in the Figure 7 embodiment referred to above,
any selected frame element 12 could be removed from model
10 by withdrawing the three flexible rods 24 which pass
through that particular frame element 12. The other frame
elements 12 forming model 10 are maintained in their
designated spacial position by the rPm~ n; ng flexible rods
24.
In further alternative embodiments, resilient
spacers 28 could be positioned on rods 24 between adjacent
elements 12 to bias each element 12 toward its designated
spacial position within model 10 (Figure lO(c)). Spacers
28 could consist of coiled springs, foam pads or the like.
As in the Figure 7 embodiment, the interior elements 12 of
CA 022~8774 1998-12-18
,
WO98/~W9l PCTICA961~510
- 27 -
model 10 could be readily visualized, while still maintain-
ing the relative positional relationship between elements
12, by sliding the exterior elements 12 toward one side or
another of model 10 against the bias of spacers 28.
As should be apparent to someone skilled in the
art, the outer diameter of the flexible rods 24 illustrated
in Figure 10 could be less than the diameter of apertures
26 ~since elements 12 could be maintained in position by
spacers 28 rather than frictional forces). For example,
each flexible rod 24 could have an outer diameter approxi-
mately 1/3 the size of frame element apertures 26. As
shown best in Figure 12, if smaller diameter rods 24 are
used, then the mutually perpendicular apertures 26 could be
intersecting rather than non-intersecting.
With reference to Figure 11, the end portions of
rods 24 could be adapted to hold frame elements 12 together
in the form o~ a cubical model 10. The Figure 11 embodi-
ments are particularly useful if smaller diameter rods 24are used (since frictional forces alone will not maintain
the frame elements 12 in position).
Figure ll(a) illustrates a flexible rod 24, such
as a thin filament, having a loop 30 formed at each end.
Rod 24 is first threaded through the apertures 26 formed in
the frame elements 12 in question and is then secured to
the outermost elements 12 by inserting a short pin 32
through each loop 30. Pins 32 act as removable barriers
preventing the frame elements from sliding off the ends of
rod 24.
Figure ll(b) illustrates an alternative embodi-
ment wherein an end portion 34 of rod 24 is threaded. A
cap 36 may be releasably secured to end portion 34 after
the frame elements 24 have been assembled on rod 24.
CA 02258774 1998-12-18
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WO98/~91 PCT/CA961W~10
- 28 -
In the Figure ll(c) embodiment rod 24 has a
notched end 38 which is shaped to receive a removable plug
40. Like pin 32 and cap 36, plug 40 acts as a barrier
preventing unintentional disassembly of model lO.
Many other alterations and modifications are
possible in the practice of this invention without depart-
ing from the spirit or scope thereof. Accordingly, the
scope of the invention is to be construed in accordance
with the substance defined by the following claims.
CA 02258774 1998-12-18
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