Note: Descriptions are shown in the official language in which they were submitted.
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
METHODS AND APPARATUS FOR
COLOR CALIBRATION AND VERIFICATION
Backaround of the Invention
This invention relates to color measuring
instruments and, in particular, to methods and
apparatus for calibrating and verifying the calibration
of color measuring instruments that are suitable for
measuring the color of a surface, including human skin.
It is well known that color measuring
instruments, such as colorimeters and
spectrophotometers, can be used to measure the color of
surfaces for a variety of useful applications. For
example, Macfarlane et al. U.S. Patent No. 5,313,267
describes a method and instrument for selecting
personal compatible colors using a color measuring
device. Also, PCT Publication No. WO 96/41140
describes methods and apparatus for determining the
condition of .a test subject based on color by using a
color measuring instrument to detect change in a color
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
- 2 -
factor indicative of a condition such as a disease,
spoilage, ageing, etc. In particular, those methods
and apparatus can be used to detect a medical condition
known as hyperbilirubinemia by measuring skin color.
However, in order to ensure that the skin.
color measurements are accurate, they are usually
preceded by conventional calibration and optionally
conventional verification techniques. Such calibration
can be performed by measuring a single color standard
of predetermined coloration having premeasured color
measurement values) and comparing the measurement
values) with the premeasured values) to see that they
are substantially the same. Once calibrated, the
instrument is normally prepared to perform accurate
color measurements producing color measurement valuets)
that characterize the color of an unknown sample.
Additionally, further subsequent verification
against a color standard that is different than that of
the color standard used during calibration can help to
ensure that the standard used to calibrate the color
measuring instrument was an accurate and authorized
color standard for its intended calibration and that
calibration was performed according to predetermined
specifications .
When color measuring instruments are used for
medical applications, such as when they are used to
detect abnormal medical conditions (including
hyperbilirubinemia), the accuracy of the color standard
used for calibration and verification is critical.
However, color standards may be inaccurate because they
have been inadvertently scratched and/or soiled by
previous users or because they have become discolored,
or faded, from atmospheric or electro-magnetic
radiation exposure. Furthermore, another reason for
inaccuracy of the color standard includes poor quality
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
- 3 -
control at the site where the color standard is
manufactured. Poor quality control at the
manufacturing site may yield unacceptable variability
in coloration of a color standard (even though the
color standard is new and unused). Moreover, color .
standards from unauthorized manufacturing sites may be
mislabeled.
Furthermore, when a color measuring
instrument is used to determine a medical condition, a
portion of the instrument usually makes an optical seal
on the surface of the patient s skin. In order to make
the seal, however, that portion of the color measuring
instrument normally makes physical contact with the
skin. A disadvantage of such contact is that the
contacting surface of the instrument could transfer
germs between successive patients when a single color
measuring instrument is used to make such measurements.
In view of the foregoing, it is an object of
this invention to provide sanitary methods and
apparatus for making color measurements of human skin
among other uses fo.r such an invention, such as
measuring laboratory specimens.
It is yet another object of this invention to
provide improved color calibration and verification
methods and apparatus that can detect inaccurate or
unauthorized color standards and inaccurate calibration
of color measuring instruments.
It is another object of this invention to
provide methods and apparatus for safely measuring
medical conditions without the risk of germ transfer.
Summary of the Invention
These and other objects of the invention are
accomplished in accordance with the principles of the
invention by providing methods and apparatus to ensure
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
- 4 -
proper calibration and verification of calibration of
color measuring instruments.
As used herein, the term "calibration"
includes both conventional calibration and
standardization techniques as defined by Standard
Terminology of Appearance (ASTM definitions).
Conventional color calibration is the finding and
elimination of systematic errors of a color measurement
instrument scale or method of measurement by use of
material standard and techniques traceable to an
authorized national or international measurement
system. Standardization is the process of adjusting
the instrument output to correspond to a previously
established calibration using one or more specimens or
reference materials.
A method of calibrating a color measuring
instrument with a color standard and verifying the
color standard and the calibration according to this
invention can include the following steps. First, a
color standard having a surface with at least two
different colors is provided. Second, the color
measuring instrument is calibrated. And third, the
calibration of the color measuring instrument is
verified.
The color standard used in a preferred
embodiment is one having at least two different colors
arranged for simultaneous color measurement to
sequentially calibrate a color measuring instrument
with first predetermined color measurement values) of
the color standard and verify the calibration with at
least second and different predetermined color
measurement values) of the color standard, the color
calibration and verification apparatus includes
variance means to provide at least such first and
second different color measurement values, the variance
CA 02315183 2000-06-14
WO 99/32861 PCTNS98I27070
- 5 -
means being selected from the group consisting of:
(1) sequential inclusion and exclusion of the
predetermined color measurement values) of the
predetermined color measurement values) of a portion
of said colors, (2) sequential exclusion and inclusion
of the predetermined color measurement values) of the
predetermined color measurement values) of a portion
of said colors, and (3) sequential unexposure and
exposure of photosensitive paper or material which
provides at least one of said colors or portion of said
colors.
The color standard used in another preferred
embodiment of this invention has a first color that is
characterized by a first predetermined coloration
having premeasured color measurement values) and a
second color that is characterized by a second
predetermined coloration having premeasured color
measurement value(s). The color standard used in
calibrating and verifying a color measuring instrument
can include: (1) a first predetermined coloration's
premeasured color measurement value(s), (2) a second
predetermined coloration's premeasured color
measurement valuets), or (3) any combination of the
first and the second predetermined coloration's
premeasured color measurement value(s).
Any portion, region, or section of the color
standard can be photosensitive so that its color
changes in a known way when exposed to a predetermined
dose of light.
The surface of the color standard can be a
single surface with two colors or, in another preferred
embodiment, can be two separate surfaces with two
respective colors. For example, a first color which is
characterized by a first predetermined coloration
having premeasured color measurement values) can be
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
- 6 -
disposed on a first surface of the color standard and a
second color (which is characterized by a second
predetermined coloration having premeasured color
measurement value(s)) can be disposed on a second
surface of the color standard. The second surface can
be the opposite side of the first surface.
When two or more colors are disposed on a
single surface, the colors are preferably arranged for
a simultaneous color measurement. A simultaneous color
measurement according to this invention includes one
color measurement of a single portion having two or
more colors. Although the colors are preferably
arranged so that a simultaneous color measurement can
be made according to this invention, one or more of the
colors can be measured separately or in combination.
Furthermore, one or more simultaneous color
measurements can be performed during a single
calibration or verification.
Preferably, the color standard used according
to this invention is substantially opaque or has a
surface against the back of the color standard that is
opaque.
Suitable color standards for skin color
measurements for detecting conditions affecting
hyperbilirubinemia can be chosen using skin color
categories. Skin color categories are disclosed in
Macfarlane et al. U.S. Patent No. 5,671,735, Macfarlane
et al. U.S. Patent Application Ser. No. 08/939,462,
filed on September 29, 1997, Macfarlane et al. U.S.
Patent Application Ser. No. 08/939,588, filed on
September 29, 1997, Macfarlane et a1. U.S. Patent
Application Ser. No. 08/939,784, filed on
September 29, 1997, Macfarlane et al. U.S. Patent
Application Ser. No. 08/939,232, filed on
September 29, 1997, and PCT Publication No. WO 96/4114C
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
(which are hereby incorporated by reference in their
entirety herein). By using combinations of these
categories of colors as the colors described on color
standard surface for the calibration or verification of
the invention herein, it could in some cases provide.
greater accuracy in measuring the color of skins for
detecting abnormal medical conditions, such as
hyperbilirubinemia. Suitable color standards for hair
color measurements can be chosen using hair color
classifications. Hair color classifications are
disclosed in Macfarlane et al. U.S. Patent Application
Ser. No. 08/657,590, filed June 7, 1996, and PCT
Publication No. WO 96/41139 (which are hereby
incorporated by reference in their entirety herein).
A color measuring instrument and a
calibration and verification apparatus for calibrating
and further verifying the calibration are also
provided.
Brief Description of the Drawings
FIG. 1 is a simplified illustrative
embodiment of a color measuring instrument being used
with a calibration and verification apparatus against a
surface of a sample of unknown colorization, in
accordance with this invention.
FIGS. 2A-2D are planar views of various
illustrative embodiments of color standards, in
accordance with this invention.
FIG. 3 is an exploded perspective view of an
illustrative embodiment of a calibration and
verification apparatus, in accordance with this
invention. FIG. 3 also shows a head of a color
measuring instrument on which the apparatus can be
mounted.
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
_ g _
FIG. 4A is an exploded perspective view of
another illustrative embodiment of a calibration and
verification apparatus, including a variable aperture
mask, frame, and color standard, in accordance with
this invention. FIG. 4A also shows a head of a colox
measuring instrument on which the apparatus can be
mounted.
FIG. 4B is a perspective view of the variable
aperture mask and frame shown in FIG. 4A in a "closed"
position, in accordance with this invention.
FIG. 4C is a perspective view of the variable
aperture mask and frame shown in FIG. 4A in an "open"
position, in accordance with this invention.
FIG. 5A is an exploded perspective view of
yet another illustrative embodiment of a calibration
and verification apparatus, including another variable
aperture mask, frame, and color standard, in accordance
with this invention. FIG. 5A also shows a head of a
color measuring instrument on which the apparatus can
be mounted.
FIG. 5B is a perspective view of the variable
aperture mask and frame shown in FIG. 5A in a "closed"
position, in accordance with this invention.
FIG. 5C is a perspective view of the variable
aperture mask and frame shown in FIG. 5A in an "open"
position, in accordance with this invention.
FIG. 6A is a planar view of still another
illustrative embodiment of a color standard, in
accordance with this invention.
FIG. 6B is a planar view of a mask that can
be used with the color standard shown in FIG. 6A in
accordance with this invention.
FIG. 6C is a side view of yet another
illustrative embodiment of a calibration and
verification apparatus that can be used with the color
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
- 9 -
standard shown in FIG. 6A and the mask shown in
FIG. 6B, in accordance with this invention.
FIG. 6D is a cross-sectional view of the
calibration and verification apparatus taken from
line 6D-6D of FIG. 6C, in accordance with this
invention.
FIG. 6E is a side view of yet another
illustrative embodiment of a calibration and
verification apparatus that can be used with the color
standard shown in FIG. 6A and the mask shown in
FIG. 6B, in accordance with this invention.
FIG. 6F is a cross-sectional view of the
calibration and verification apparatus taken from
line 6F-6F of FIG. 6E, in accordance with this
invention.
FIG. 7A is a side cross-sectional view of yet
another illustrative embodiment of a calibration and
verification apparatus that can be used in accordance
with this invention.
FIG. 7B is a cross-sectional view of the
calibration and verification apparatus taken from
line 7B-7B of FIG. 7A with a mask in a first operable
position, in accordance with this invention.
FIG. 7C is a cross-sectional view of the
calibration and verification apparatus taken from
line 7C-7C of FIG. 7A with a mask in a second operable
position, in accordance with this invention.
FIG. 8 is an exploded perspective view of
still another illustrative embodiment of a calibration
and verification apparatus, including a frame and a
color standard, in accordance with this invention.
FIG. 8 also shows a head of a color measuring
instrument on which the apparatus can be mounted.
FIG. 9 is an exploded perspective view of yet
another illustrative embodiment of a calibration and
CA 02315183 2000-06-14
WO 99/32861 PCT1US98/27070
- 10 -
verification apparatus using a photosensitive layer in
accordance with this invention. FIG. 9 also shows a
head of a color measuring instrument on which the
apparatus can be mounted.
FIG. 10 is a perspective view of the
calibration and verification apparatus shown in FIG. 9
where the apparatus is in an assembled configuration.
FIG. 10 also shows a head of a color measuring
instrument on which the apparatus can be mounted.
FIG, 11 is an exploded perspective view of
yet another illustrative embodiment of a calibration
and verification apparatus using a photosensitive layer
in accordance with this invention. FIG. 11 also shows
a head of a color measuring instrument on which the
apparatus can be mounted.
FIG. 12 is a perspective view of the
calibration and verification apparatus shown in FIG. 11
where the apparatus is in an assembled configuration.
FIG. 12 also shows a head of a color measuring
instrument on which the apparatus can be mounted.
FIG. 13 is a cross-sectional side view of yet
a further illustrative embodiment of a calibration and
verification apparatus using a photosensitive layer in
accordance with this invention, where the apparatus is
in an assembled configuration.
FIG. 14 is a cross-sectional exploded side
view of the calibration and verification apparatus
shown in FIG, 13.
FIG. 15 is a top view, partly in section, of
the calibration and verification apparatus shown in
FIG. 13.
FIG. 16 is a cross-sectional side view of yet
a further illustrative embodiment of a calibration and
verification apparatus using a photosensitive portion
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/Z7070
- 11 -
in accordance with this invention, where the apparatus
is in an assembled configuration.
FIG. 17 is a cross-sectional exploded side
view of the calibration and verification apparatus
shown in FIG. 16.
FIG. 18 is a top view, partly in section, of
the calibration and verification apparatus shown in
FIG. 16.
FIG. 19 is a cross-sectional side view of yet
a further illustrative embodiment of a calibration and
verification apparatus using a photosensitive layer in
accordance with this invention, where the apparatus is
in an assembled configuration.
FIG. 20 is a cross-sectional exploded side
view of the calibration and verification apparatus
shown in FIG. 19.
FIG. 21 is a top view, partly in section, of
the calibration and verification apparatus shown in
FIG. 19.
Detailed Description of the Preferred Embodiments
According to one aspect of this invention, a
color calibration and verification apparatus for
calibrating and verifying the calibration of a color
measuring instrument is provided. In one embodiment,
the apparatus includes a color standard having a
surface with at least two different colors arranged for
a simultaneous color measurement. In another
embodiment, the apparatus includes a color standard
having a surface with at least a first region and a
second region, wherein the first region has a first
color characterized by a first predetermined coloration
having premeasured color measurement value(s), and
wherein the second region is photosensitive and has a
second color characterized by a second predetermined
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
- 12 -
coloration having premeasured color measurement values
prior to exposure to light and after exposure to light
of a predete~nined quantity, and is adequately
photosensitive to allow a sufficient change in color by
exposure to a predetermined quantity of light for the
color measurement instrument to differentiate the color
measurement values prior to exposure and after exposure
to such light.
According to another aspect of this
invention, color measuring instruments and methods for
calibrating and verifying color measuring instruments
are provided.
In one embodiment, a method for calibrating a
color measuring instrument and verifying the
calibration is provided. The method can include:
(a) providing a color standard having a
substantially opaque surface with at least two
different colors arranged for simultaneous color
measurement;
(b) sequentially calibrating the
instrument with first predetermined color measurement
values) of the color standard and verifying the
calibration with at least second and different
predetermined color measurement values) of the color
standard;
(c) providing variance means to provide
said first and second different color measurement
values, said variance means being selected from the
group consisting of: (1) sequential inclusion and
exclusion of predetermined color measurement values)
of a portion of said colors, (2) sequential exclusion
and inclusion of predetermined color measurement
values) of a portion of said colors, and
(3) sequential unexposure and exposure of
photosensitive paper or material which provides at
CA 02315183 2000-06-14
WO 99/32861 PCTNS98127070
- 13 -
least one of said colors or region or portion of said
colors;
(d) calibrating said instrument with
said first predetermined color measurement values) of
the color standard;
(e) causing the variance means to
provide at least second and different predetermined
color measurement values) of the color standard; and
(f) verifying the calibration of the
color measurement instrument with said at least second
and different predetermined color measurement values)
of the color standard.
In another embodiment, a method for
calibration of a color measuring instrument and
verification of the calibration using a color
calibration and verification apparatus is provided. An
apparatus for use with the method includes: (a) a color
standard having a substantially opaque surface with at
least two different colors arranged for simultaneous
color measurement to sequentially calibrate the
instrument with first predetermined color measurement
values) of the color standard and verify the
calibration with at least second and different
predetermined color measurement values) of the color
standard, and (b) variance means to provide first and
at least second different color measurement values, the
variance means being selected from the group consisting
of: (1) sequential inclusion and exclusion of
predetermined color measurement values) of a portion
of the colors, (2) sequential exclusion and inclusion
of predetermined color measurement values) of the
portion of the colors, and (3) sequential unexposure
and exposure of photosensitive paper or material which
provides at least one of the colors or portion of the
colors. The method includes (a) calibrating the
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
- 14 -
instrument with first predetermined color measurement
values) of the color standard; (b) causing the
variance means to provide at least second and different
predetermined color measurement values) of the color
standard; and (c) verifying the calibration of the
color measurement instrument with at least second and
different predetermined color measurement values) of
the color standard.
The color measuring instrument for use with
this method includes: (a) means for calibrating the
instrument with first predetermined color measurement
values) of the color standard; (b) means for causing
the variance means to provide at least second and
different predetermined color measurement values) of
the color standard; and (c) means for verifying the
calibration of the color measurement instrument with at
least second and different predetermined color
measurement values) of the color standard.
According to one aspect of this invention,
calibrating can include at least measuring a known and
predetermined portion of the color standard to obtain
calibration color measurement value(s), and verifying
can include at least measuring a second known portion
to obtain verification color measurement value(s).
When the first and second known portions are the same,
exposing preferably includes exposing at least the
second color (i.e., photosensitive region) to a
predetermined dose of light such that the calibration
color measurement values) and the verification color
measurement values) are different.
In another embodiment, the method includes:
(1) providing a color standard having a surface with at
least two different colors arranged for a simultaneous
color measurement; (2) calibrating the instrument; and
(3) verifying that the color standard used in
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
- 15 -
calibration is an authorized color standard of the
predetermined specification and that the calibration of
the color measuring instrument has achieved
predetermined specified results.
The color measuring instrument for use with
this method includes: (1) means for calibrating with
the color standard; and (2) means for verifying that
the color standard used in calibration is an authorized
color standard of the predetermined specification and
that the calibration of the color measurement
instrument has achieved predetermined specified
results.
According to another aspect of this
invention, another method includes: (1) providing a
color standard having a surface with at least a first
region and a second region, wherein the first region
has a first color characterized by a first
predetermined coloration having premeasured color
measurement value(s), and wherein the second region is
photosensitive; (2) calibrating the instrument with the
apparatus; (3) exposing at least the second region to
light; and (4) verifying that the color standard used
in calibration is an authorized color standard of the
predetermined specification and that the calibration of
the color measurement instrument has achieved
predetermined specified results.
The color measuring instrument for use with
this method includes: (1) means for calibrating;
(2) means for exposing at least the second region to
light; and (3) means for verifying that the color
standard used in calibration is an authorized color
standard of the predetermined specification and that
the calibration of the color measurement instrument has
achieved predetermined specified results.
CA 02315183 2000-06-14
WO 99/32861 PCTNS98/27070
- 16 -
Either of the above methods can include the
following steps:
(1) providing a color standard having a
surface with at least two different colors, a first of
the colors being characterized by a first predetermined
coloration having premeasured color measurement
values) and a second of the colors being characterized
by a second predetermined coloration having premeasured
color measurement value(s);
(2) calibrating the instrument, the
calibrating comprising:
measuring at least a ffi rst known
and predetermined portion of the color standard surface
to obtain preliminary calibration color measurement
value(s), adjusting the instrument output to correspond
to previously established calibrations, using the
portion of the color standard and remeasuring the
portion of the color standard to obtain calibration
color measurement values) and
comparing the calibration color
measurement values) with a calibration's premeasured
color measurement values) for the same known and
predetermined portion of the color standard surface to
ensure that the calibration color measurement values)
and the calibration's premeasured color measurement
values) is substantially the same and therefore to
ensure that calibration has achieved predetermined
specified results; and
(3) verifying that the color standard
used in calibration is an authorized color standard of
the predetermined specification and that the
calibration of the color measurement instrument has
achieved predetermined specified results, the verifying
comprising:
CA 02315183 2000-06-14
WO 99/32861 PC?/US98/27070
- 17 -
measuring at least a second known
and predetermined portion of the color standard surface
to obtain verification color measurement value(s), and
determining that the verification
color measurement values) is substantially equal to.a
verification s premeasured color measurement values)
for the same known and predetermined portion of the
color standard surface.
With a color standard having at least two
different colors arranged for simultaneous color
measurement to sequentially calibrate a color measuring
instrument with first predetermined color measurement
values) of the color standard and verify the
calibration with a second and different predetermined
color measurement values) of the color standard, the
color calibration and verification apparatus includes
variance means to provide such first and second
different color measurement values, the variance means
being selected from the group consisting of
(1) sequential inclusion and exclusion of at least the
predetermined color measurement values) of a portion
of said colors, (2) sequential exclusion and inclusion
of at least the predeterniined color measurement
values) of a portion of said colors, and
(3) sequential unexposure and exposure of
photosensitive paper or material which provides at
least one of said colors or portion of at least one of
said colors.
FIG. 1 shows a simplified illustrative
embodiment of color measuring instrument 10 and
calibration and verification apparatus 20 in accordance
with this invention. Instrument 10 can be a color
measuring instrument such as a colorimeter or a
spectrophotometer or other color measuring instrument
suitable for measuring the color of a sample
CA 02315183 2000-06-14
WO 99/32$61 PCT/US9$/Z7070
- 18 -
surface 30, such as hair, teeth, matter, materials, or
human skin. Sensor head 15 is usually at one end of
instrument 10. In order to ensure that measurements of
such samples are accurate, such measurements are
usually preceded by calibration and optionally
verification. Calibration is usually performed by
measuring a single color standard with known
premeasured color measurement values) and comparing
the measurement values) with the premeasured known
values) to see that they are substantially the same.
Once calibrated, the instrument is normally prepared to
perform accurate color measurements producing color
measurement values) that characterize the color of an
unknown sample. However, when the calibration of the
color measuring instrument is not performed correctly,
such as when the color standard used during calibration
was inaccurate for the intended calibration results, a
subsequent color measurement of a sample with unknown
color will be inaccurate. Thus, subsequent
verification against a color standard different than
that of the color standard used to calibrate can
further ensure that the standard used to calibrate the
machine was an accurate and authorized color standard
for its intended calibration.
In accordance with one aspect of this
invention, a method of color calibration and
verification includes: (1) providing a color standard
having a surface with at least two different colors,
(2) calibrating a color measuring instrument by
measuring one known portion of the color standard
surface, including adjusting the instrument output to
correspond to previously established calibration, using
the color standard and remeasuring the color standard
used in calibration to ensure the calibration achieved
predetermined specified results and (3) verifying by
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
- 19 -
measuring another known portion of the color standard
surface to verify that the color standard used to
calibrate is an authorized color standard having
predetermined specifications and that the calibration
of the color instrument has achieved predetermined
specified results.
A color standard according to this aspect of
the invention has a surface with at least two different
colors. A first color is characterized by a first
predetermined coloration having premeasured color
measurement value(s). A second color can be
characterized by a second predetermined coloration
having premeasured color measurement value(s). The
color standard is preferably substantially opaque, or
has a back surface that is substantially opaque, with
at least two colors that are arranged for a
simultaneous color measurement.
As used herein, a color measurement value is
any coordinate in any predefined color space. Examples
of color spaces include, for example, XYZ Tristimulus
value space (CIE 1931) , XloYioZlo Tristimulus value space
(CIE 1964), Yxy Chromacity coordinate space, L*a*b*
space (CIELAB), L*C*h space, Munsell space, Hunter Lab
space, L*u*v* space (CIELW), as well as a series of
wavelengths, which can be measured in nanometers.
Color measurement values) can include one or more
color measurement values. Premeasured color
measurement values) consist of color measurement
values) that were obtained by measuring the color of a
known portion of a color standard surface of specified
predetermined coloration with a first calibrated color
measuring instrument prior to using such color standard
to calibrate a second color measuring instrument for
measuring the color of samples.
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
- 20 -
A predetermined coloration's calibration's
premeasured color measurement values) can be: (1) the
first predetermined coloration's premeasured color
measurement value(s), (2) the second predetermined
coloration's premeasured color measurement value(s),.or
(3) any combination of the first and the second
predetermined coloration's premeasured color
measurement value(s). A predetermined coloration's
calibration's premeasured color measurement values)
can consist of color measurement values) that were
obtained by measuring the color of a first known
portion of a color standard surface of specified
predetermined coloration with the first calibrated
color measuring instrument prior to using the color
standard to calibrate the second color measuring
instrument for measuring the color of samples.
A predetermined coloration's verification's
premeasured color measurement values) can be: (1) the
first predetermined coloration's premeasured color
measurement value(s), (2) the second predetermined
coloration's premeasured color measurement value(s), or
(3) any combination of the first and the second
predetermined coloration's premeasured color
measurement value(s). A predetermined coloration's
verification's premeasured color measurement values)
can consist of color measurement values) that were
obtained by measuring the color of a second known
portion of a color standard surface of specified
predetermined coloration with the first calibrated
color measuring instrument prior to using the color
standard to calibrate the second color measuring
instrument for measuring the color of samples.
After a color standard of specified
predetermined coloration is provided in the first step,
CA 02315183 2000-06-14
WO 99/32861 PCTNS98/Z7070
- 21 -
the color measuring instrument is preferably calibrated
according to the principles of this invention.
As used herein, the term "calibration"
includes both conventional calibration and
standardization techniques as defined by Standard
Terminology of Appearance (ASTM definitions).
Conventional color calibration is the finding and
elimination of systematic errors of a color measuring
instrument scale or method of measurement by use of
material standards and techniques traceable to an
authorized national or international measurement
system. Standardization is the process of adjusting
the instrument output to correspond to a previously
established calibration using one or more specimens or
reference materials.
According to this invention, calibration
includes (1) providing a color standard of
predetermined specified coloration, (2) measuring at
least a first known and predetermined portion of the
color standard surface to obtain preliminary
calibration color measurement value(s), adjusting the
instrument output to correspond to previously
established calibration, using the color standard and
remeasuring the color standard to obtain calibration
color measurement value(s), and (3) comparing the
calibration color measurement values) (or calculated
color measurement values) of a different color index,
which are calculated from the color measurement
value(s)) with calibration's premeasured color
measurement values) for the same known and
predetermined portion of the color standard surface to
ensure that the calibration color measurement values)
and the calibration's premeasured color measurement
values) are substantially the same and therefore to
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
- 22 -
ensure that calibration has achieved predetermined
specified results.
After the color measuring instrument is
calibrated using a first known portion of the color
standard surface, a second known portion of the color,
standard surface is used to verify that the color
standard used in the calibration is an authorized color
standard of predetermined specification and that the
calibration of the color measuring instrument has
achieved predetermined specified results.
According to this invention, verifying
includes (1) measuring at least a second known and
predetermined portion of the color standard surface to
obtain verification color measurement value(s), and
(2) determining that the verification color measurement
values) (or calculated verification color measurement
values) of a different color index, which are
calculated from the verification color measurement
value(s)) is substantially equal to the verification's
premeasured color measurement values) for the same
know and predetermined portion of the color standard
surface. When the verification color measurement
values) is substantially equal to a verification's
premeasured color measurement value(s), it can be
determined that the calibration achieved the
predetermined specified results and that the color
standard used for calibration and for verification was
(a) the predetermined color standard specified for
calibration and verification and (b) authorized.
The first and second colors of predetermined
coloration on the color standard surface can be
disposed on that surface in a known ratio of surface
areas. As used herein, a "known ratio of surface
areas" is any ratio of surface areas such that a
measurement of a known portion of that surface
CA 02315183 2000-06-14
WO 99/328b1 PCT/US98/Z7070
- 23 -
corresponds to a known and predetermined coloration
having premeasured color measurement value(s). This
means that the ratio of a first surface area on which
the first color of predetermined coloration is disposed
to a second surface area on which the second color of
predetermined coloration is disposed is predetermined
and known. That known ratio can be uniform over the
standard surface or it can vary over the surface, such
as radially, in a known fashion.
Alternatively, the two colors of
predetermined coloration can be disposed on the color
standard surface in a known configuration. As used
herein, a "known configuration" is any arrangement of
colors such that a measurement of a known portion of
the color standard surface corresponds to a known and
predetermined coloration having premeasured color
measurement value(s).
A known ratio or configuration permits a
variety of calibration and verification methods
according to this invention.
FIGS. 2A-2D show four embodiments of a color
standard with at least two different colors of
predetermined coloration according to this invention.
FIG. 2A shows color standard surface 2.05 having a first
color of predetermined coloration disposed on central
portion 210 of surface 205 and a second color of
predetermined coloration disposed on outer portion 215,
which is disposed radially outside central portion 210.
Preferably, portions 210 and 215 are disposed in a
radially symmetric fashion, as shown in FIG. 2A.
FIG. 2B shows color standard surface 220 having a first
color of predetermined coloration disposed on semi-
circular portion 225 of surface 220 and a second color
of predetermined coloration disposed on adjacent semi-
circular portion 230 of surface 220. FIG. 2C shows
CA 02315183 2000-06-14
WO 99/32861 PCTNS98/27070
- 24 -
color standard surface 235 having a first color of
predetermined coloration disposed on slices 240 and a
second color of predetermined coloration disposed on
slices 245 of surface 235.
A color standard in accordance with this
invention can have three or more colors of
predetermined coloration, as shown in FIG. 2D. Color
standard 250 of FIG. 2D has a first color of
predetermined coloration disposed on a central
portion 255, a second color of predetermined coloration
disposed on portion 260 that is radially outside
portion 255, a third color of predetermined coloration
disposed on portion 265 that is radially outside
portion 260, and portion 270 that is radially outside
portion 265. Although color standard 250 shows four
different colors of predetermined coloration, a person
of ordinary skill in the art would understand that any
number of colors of predetermined coloration can be
disposed on surface 250 in accordance with this
invention. Also, the colors of predetermined
coloration can be disposed on the surface of a color
standard in a substantially random fashion, as long as
within that random disposition of colors of
predetermined coloration each color or gradation of
color has a predetermined coloration of premeasured
color measurement values) for subsequent use in
calibration and verification.
A common feature of the color standards shown
in FIGS. 2A-2D is that they all have predetermined and
known color configurations so that a measurement of a
known portion of that surface will correspond to known
color of predetermined coloration having premeasured
color measurement value(s).
According to one aspect of the invention, the
two different colors on the color standard can differ
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
- 25 -
only by a single premeasured color measurement value,
such as when the predetermined coloration's premeasured
color measurement values) are measured in CIE Hunter
Lab space (1948) and only the lightness color
measurement value L is different. In this case, and .
according to this invention, the two colors would be
considered to have different premeasured color
measurement value(s), as long as the value of L
differed, preferably by at least 3 points.
One method of achieving a very high L value
is by providing a high gloss finish to a region of the
color standard. In fact, when the high gloss finish is
applied to a region of the color standard, the L value
that corresponds to that region can be extremely large
(greater than 80 or 90 points). However, such high
gloss finishes also tend to strongly affect (usually
increase) the value of the other premeasured color
measurement value(s), that is the a and b values.
Therefore, in order to make a color
measurement of a portion of a color standard having a
high L value and relatively unaffected (or low) a and b
values, that portion, which can be measured during
calibration and/or verification, must include a region
having at least one color with a large L value (e.g., a
value greater than about 80 points, and preferably
greater than about 90 points) and a second color with a
relatively small L value and substantially unaffected
(e. g., low) a and b values.
Thus, in accordance with one aspect of the
present invention, calibration and verification can be
performed according to this invention by using a color
standard with two different colors,.a first of which
has a high gloss finish and a second of which has a
matte, a low gloss (or no gloss) finish. In an
unauthorized color standard on which the high gloss
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/2?070
- 26 -
finish was provided over the whole known portion, the a
and b values would necessarily be large. Thus, if a
color measuring instrument was programmed to only
calibrate and verify with a high L value and low a and
b values, non-authorized color standards could be
detected and rejected according to this invention. It
should be clear, however, that while this aspect of the
invention is described in terms of CIE Hunter Lab
space (1948), any color coordinates of any color index
can be used to describe the colorization of a color
standard in accordance with this invention.
Calibration according to this invention can
be performed by measuring any known and predetermined
portion of the color standard surface. Therefore, a
calibration measurement can include measuring a known
and predetermined portion of the standard surface on
which a single color of predetermined coloration is
disposed, two colors of predetermined coloration are
disposed, or three or more colors of predetermined
coloration are disposed, as long as that portion
corresponds to a known color of predetermined
coloration having premeasured color measurement
value(s).
In accordance with this invention,
calibration can be performed using a color calibration
and verification apparatus. FIG. 3 shows an
illustrative embodiment of color calibration and
verification apparatus 300. Apparatus 300 includes
mask 310, frame 320, and color standard 330. Color
standard 330 is removably fastened to frame 320. Color
standard 330 can have tab portion 331 for a user to
grasp when removal of color standard 330 is desired.
Mask 310 is mounted, preferably removably mounted,
between color measuring instrument sensor head 340 and
color standard 330. Mask 310 can also have tab
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
- 27 -
portion 311 for a user to grasp when removal of
mask 310 is desired. Also, frame 320 can itself act as
a mask to some degree:
During calibration with apparatus 300,
calibration color measurement values) can be obtained
by measuring a first known portion of color
standard 330. In FIG. 3, the first color of
predetermined coloration is disposed centrally on
standard 330 and the second color of predetermined
coloration is disposed on an annular region radially
outside the central region of standard 330. The shape,
size, and position of aperture 312 of mask 310
determines the first known portion measured during
calibration. That portion can include all of the first
color of predetermined coloration, part of the first
color of predetermined coloration, or none of the first
color of predetermined coloration. As shown in FIG. 3,
however, mask 310 blocks the outer annular region so
that first known portion 332 of standard 330 is
measured alone. When aperture 312 is made larger, the
first known portion includes all of the central region
characterized by the first color of predetermined
coloration and part of the annular region characterized
by the second color of predetermined coloration. When
aperture 312 is made smaller than the central region
(i.e., surface area on which the first color is
disposed), only a part of the central region is
measured and none of the annular region is measured.
Therefore, the regions that are characterized by
different colors can be arranged so that they can be
simultaneously measured. However, such an arrangement
does not mean that every color measurement includes two
or more different colors.
After calibration is performed using
calibration and verification apparatus 300 shown in
CA 02315183 2000-06-14
WO 99/32861 PCTJUS98/27070
- 28 -
FIG. 3, the calibration and the color standard can be
verified after removing mask 310. Mask 310 can be
removed from apparatus 300 by any convenient method,
including grasping and then pulling tab portion 311 of
mask 310 until mask 310 no longer blocks light from
entering the color measuring instrument.
Alternatively, mask 310 could be removed by
(1) unfastening apparatus 300 from color measuring
instrument head 340 to expose mask 310, (2) pulling tab
portion 311 of mask 310 until mask 310 is removed from
apparatus 300, and (3) replacing apparatus 300 on color
measuring instrument head 340.
After mask 310 is removed, the second known
portion of color standard 330 includes substantially
the entire color standard surface, including all of
first known portion 332. In particular, second known
portion 334 would include a surface on which the first
and second colors of predetermined coloration are
disposed.
Second known portion 334, which is used
during verification, can be any portion of the standard
surface, such as a portion that includes first known
portion 332. Like calibration, verification can be
performed by measuring any known portion of the color
standard surface. As described more fully below, first
known portion 332 and second known portion 334 can
correspond to the same surface area, such as when at
least one of the two colors are photosensitive.
Therefore, a verification measurement (or alternatively
a calibration measurement) can include measuring a
known and predetermined portion of the standard surface
on which a single color of predetermined coloration is
disposed, two colors of predeteztnined coloration are
disposed, or three or more colors of predetermined
coloration are disposed, as long as that known portion
CA 02315183 2000-06-14
WO 99/3Z8b1 PCT/US98/27070
- 29 -
corresponds to known color of predetermined coloration
having premeasured color measurement value(s). When
two or more colors are used, they are preferably
arranged for one or more simultaneous color
measurements. After calibration is performed using .
calibration and verification apparatus 300 shown in
FIG. 3, the calibration and the color standard may be
verified after removing mask 310. Then, the second
known portion of color standard 330 would include
substantially the entire color standard surface
including first known portion 332 and would be a
portion of the color standard surface on which the
first color of predetermined coloration and the second
color of predetermined coloration are disposed.
According to another embodiment of this
invention, the aperture of a mask can have a variable
size. For example, as shown in FIGS. 4A-4C,
calibration and verification apparatus 400 includes
mask 410, frame 420, and color standard 430. Color
standard 430 (shown in FIG. 4A) is similar to color
standard 205, shown in FIG. 2A. Color standard 430 is
preferably fastened to frame 420 so that its
calibration and verification surface faces color
measuring instrument sensor head 440. Color
standard 430 can have tab portion 431 for a user to
grasp when color standard removal is desired. Mask 410
is mounted between head 440 and color standard 430 and
can include a plurality of opaque elements 412 that can
move relative to each other to change the diameter of
central aperture 422 in order to mask a variable
portion of color standard 430 (mask 410 is sometimes
referred to as an iris). Mask 410 preferably has at
least two operable positions determined by the relative
positions of opaque elements 412, but can have more
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
- 30 -
depending on the number of individual calibration and
verification measurements desired.
FIG. 4B shows frame 420 and mask 410 in a
first operable position where mask 410 masks a radially
outer part of the color standard surface. In that .
position, only first known portion 432 is measurable.
FIG. 4C shows mask 410 in a second operable position,
in which case only a small outer part of the color
standard surface is masked. In that case, second known
portion 434 is a portion that includes first
portion 432 plus a part of the previously masked
surface (an adjacent portion radially outside first
known portion 432). When mask 410 is in a
predetermined intermediate position (not shown) between
the first and second operable positions, a
predetermined combination of colors of predetermined
coloration is measurable. Of course, the color
configuration of the color standard can be any known
configuration and need not be the particular standard
shown in FIG. 4A.
FIGS. 5A-5C show another calibration and
verification instrument 500, which includes mask 510
(including mask elements 510a and 510b), frame 520, and
color standard 530. Color standard 530 shown in FIG. 5
is again similar to color standard 220 shown in
FIG. 2B, however that color standard can have any known
color configuration of predetermined coloration in
accordance with this invention. Color standard 530 is
fastened to frame 520 so that the color standard
surface faces color measuring instrument sensor
head 540. Color standard 530 can have tab portion 531
for a user to grasp when it is desired to remove
standard 530 from frame 520 to measure a sample of
color. Mask elements 510a and 510b can be mounted in
annular frame 520 and between head 540 and color
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
- 31 -
standard 530. Preferably, elements 510a and 510b are
slidable relative to frame 520 for masking a desired
portion of the surface of standard 530.
Mask elements 510a and 510b can also have
respective tabs 511a and 511b so that a user can slide
each of the mask elements into at least two operable
positions (including a completely removed position),
but can have more than two positions depending on the
number of individual calibration and verification
measurements desired. For example, FIGS. 5B and 5C
show mask elements in "closed" and "open" operable
positions, respectively. In the closed position, semi-
circular mask elements form a circle and substantially
block outer annular region 535 of the standard, thereby
masking first known portion 532 measurable. When
mask 510 is in the open position (shown in FIG. 5C)
second known portion 534, which includes first known
portion 532 and at least some of the previously blocked
outer annular region 535 of color standard 530, is
measurable. As described above, mask 510 can be used
in a predetermined intermediate position between the
first and second operable positions so that a
predetermined combination of colors of predetermined
coloration on the color standard surface is measurable.
In another embodiment according to this
invention, a color standard can have a plurality of
portions that can be measured during calibration and/or
verification. When used to calibrate, the measurable
portion on the color standard surface is referred to as
a first known portion. When used to verify, the
measurable portion is referred to as a second known
portion. FIG. 6A shows color standard 600, which
includes five regions 602, 604, 606, 608, and 610 with
different colors disposed thereon. A first known
portion, then, can be any of these five regions or,
CA 02315183 2000-06-14
WO 99/32861 PCTNS98/27070
- 32 -
depending on the mask used and its relative position, a
predetermined combination of these regions. Similarly,
a second known portion can be any of the regions or a
predetermined combination of these regions. Any of the
five regions can be photosensitive, as described more
fully below.
FIG. 6B shows an illustrative embodiment of a
mask that can be used in combination with color
standard 600 is mask 620. Mask 620 is preferably
substantially flat and has aperture 622. Mask 620 can
be constructed with any material that is opaque to
visible wavelengths of light, and is preferably black.
A first known portion, or calibration
portion, of standard 600 can be selected by adjusting
the relative position between color standard 600 and
mask 620. Adjusting the relative position can involve
rotating color standard 600 or mask 620 while the other
is ffixed.
For example, FIGS. 6C and 6D show calibration
and verification apparatus 630 in which color
standard 600 is rotatable and mask 620 is fixed.
Apparatus 630 can therefore include color standard 600,
mask 620, and frame 632. Frame 632 is mountable to
sensor head 640 of a color measuring instrument (not
shown) and color standard 600 is fastened to movable
frame element 633 such that the surface of color
standard 600 faces a light detector, or sensor, in
instrument head 640. The desired position of
standard 600 can be selected by rotating frame
element 633, such as by moving handle 634, which is
fixed to movable element 633. In addition to rotating
color standard in order to define different known
portions of color standard 600 for measurement,
mask 620 can be removed entirely from apparatus 630, in
which case the known portion would include
CA 02315183 2000-06-14
WO 99/32861 PCTNS98/27070
- 33 -
substantially the entire surface of color standard 600.
Mask 620 can be removed by grasping and pulling a tab
portion (not shown) of mask 620 and can be performed
while apparatus 630 is temporarily removed from
instrument head 640.
After calibration and verification,
standard 600 should be completely removed from movable
element 633 by peeling standard 600 away from
element 633 by grasping and pulling tab portion 601.
Standard 600 can be fastened to frame 633 with adhesive
so that standard 600 is destroyed when standard 600 is
removed from frame element 633, thereby ensuring that
an unexposed standard will be used for any subsequent
calibration or verification. After color standard 600
is removed from frame 633, frame 633 remains mounted to
head 640 of the color measuring instrument so that
color measuring instrument is ready for measuring a
sample with unknown coloration, such as human skin.
When standard 600 is removed, a sanitary
surface (rim 635) of frame 632 is preferably exposed.
That sanitary surface of rim 635 can then be placed
directly on the unknown surface (e. g., human skin)
during a subsequent color measurement. This sanitary
feature is especially useful in the medical field where
a sanitary surface reduces the possibility of
transmitting germs from one patient to another.
Mask 620 is preferably removed before measuring the
color of a sample of unknown coloration so that a large
surface area is available for the subsequent
measurement.
In an alternative embodiment, FIGS. 6E and 6F
show calibration and verification apparatus 650 in
which color standard 600 is fixed and mask 620 is
rotatable. Apparatus 650 can therefore include color
standard 600, mask 620, and frame 652. Frame 652 is
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
- 34 -
mountable to a sensor head 640 of a color measuring
instrument (not shown) and color standard 600 is
fastened to fixed frame element 653 such that the
surface of color standard 600 faces a light detector,
or sensor, in instrument head 640. In contrast to
apparatus 630, the position of mask 620 in
apparatus 650 can be selected by rotation of mask 620,
such as by moving mask handle 654, which is fixed to
element 653. Regardless of the particular apparatus
used, it should be clear to a person of ordinary skill
in the art that multiple portions can be selected on
color standard 600 for calibration and verification in
accordance with this invention.
After calibration and verification and in
accordance with the sanitary aspect of this invention,
standard 600 should be removed from movable element 633
by peeling standard 600 away from element 633 by
grasping and pulling tab portion 601. When
standard 600 is removed, a sanitary surface (rim 655)
of frame 652 is preferably exposed. Preferably,
mask 620 should also be removed before measuring the
colorization of a sample of unknown colorization in
order to maximize the measurable surface area of the
sample.
According to another embodiment of this
invention, FIG. 7 shows calibration and verification
apparatus 700. Instrument 700 includes mask 710,
frame 720, and color standard 730. Color standard 730
is similar to color standard 220 shown in FIG. 2B,
except that standard 730 is substantially square. Any
of the colors disposed on color standard 730 can be
photosensitive, as described more fully below. Color
standard 730 is fastened to frame 720 so that its
calibration and verification surface face color
measuring instrument sensor head 740. Color
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
- 35 -
standard 730 can have tab portion 731 for a user to
grasp when standard removal is desired.
Mask 710 can be slidably mounted between
head 740 and color standard 730. Accordingly, mask 711
can also have handle portion 711 to (1) facilitate .
changing the position of mask 710 between calibration
and verification and/or (2) to remove mask 711 from
frame 720 before measuring the color of an unknown
sample. Alternatively, handle portion 712 of mask 710
can also be used to remove mask 710 from frame 720.
FIG. 7B shows mask 710 in a first operable
position where mask 710 masks first known portion 732
and second known portion 734 is measurable. When
mask 710 is in a second operable position, as shown in
FIG. 7C, second known portion 734 is masked and first
known portion 732 is measurable. When mask 710 is in a
predetermined intermediate position between the first
and second operable positions, a predetermined
combination of colors of predetermined coloration
(e. g., colors on first and second portions 732 and 734)
is measurable.
The physical masking techniques described
above can be necessary when the first and second known
portions of the color standard would otherwise
simultaneously be exposed for a color measurement
without a mask. When only one of the known portions is
exposed for calibration without a mask, no mask may be
necessary. However, in order to expose the other known
portion of the color standard for verification, that
color standard may be physically moved or reoriented
between calibration and verification. One example of a
color standard with two surfaces is a flat sheet having
two opposite sides, each of which has a surface with a
predetermined coloration having premeasured color
measurement value(s). In this case the color standard
CA 02315183 2000-06-14
VNO 99/32861 PCT/US98/27070
- 36 -
must be flipped or exchanged, respectively, to expose
the appropriate surfaces during calibration and
verification. Alternatively, the two surfaces could be
on physically distinct objects, in which case the
object must be flipped or exchanged between calibration
and verification. Regardless of whether a mask is used
or not, the above-identified procedures for calibrating
and verifying according to this invention still apply.
In contrast to the actual masking techniques
used to calibrate and verify described above, the
methods described below involve constructive masking
techniques. "Actual" masking involves the physical
blocking of light so that either the first known
portion or the second known portion is at least
partially defined by a physical mask. "Constructive"
masking, however, is performed by a color measuring
instrument without a physical mask and can be used when
the first known portion and the second known portion
include the same color or the same combination of
colors -- that is, the portions correspond to the same
surface area of the color standard. Constructive
masking is useful because the color calibration and
verification apparatus used in accordance with this
aspect of the invention is simple and inexpensive to
manufacture.
FIG. 8 shows an illustrative embodiment of
color calibration and verification apparatus 800 for
use with constructive masking methods of this
invention. Apparatus 800 includes frame 820 and color
standard 830. Color standard 830 is removably fastened
to frame 820. As already described above, color
standard 830 can have tab portion 831 for easy removal
from frame 820. Removal of color standard 830 can
involve peeling color standard 830 away from frame 820
where they are attached, such as by pressure or
CA 02315183 2000-06-14
WO 99/32861 . PCT/US98/27070
- 37 -
adhesive. As in the case of physical masking
procedures, constructive masking requires that the
color standard be removed before a color measurement is
made on an unknown sample.
When calibrating with apparatus 800,
calibration color measurement values) are obtained by
measuring a known portion of color standard 830. Color
standard 830 is similar to standard 205 shown in
FIG. 2A, but can be any color standard in accordance
with this invention. For example, a color standard for
use with this aspect of the invention can have a
surface with at least two different colors in
accordance with this invention -- namely, a first color
characterized by a first predetermined coloration
having premeasured color measurement values) and a
second color characterized by a second predetermined
coloration having premeasured color measurement
value(s). Another color standard that can be used in
accordance with this invention is one having one or
more regions having a high gloss finish or that is
photosensitive.
As shown in FIG. 8, the first known portion
measured during calibration can be substantially the
entire color standard surface but can also be a
predetermined portion of that surface when a mask is
used. Of course, frame 820 can to some degree act as a
mask itself. When two or more colors are disposed on a
single surface, the colors are preferably arranged for
one or more simultaneous color measurements, even
though a color measurement of a single color alone can
also be possible. This means that first known
portion 832 and second known portion 834 can be
arranged inside the window provided by frame 820.
According to this embodiment of the
invention, standard 830 can be verified after
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
- 38 -
calibration without changing the portion of the surface
being measured. That is, the first known portion and
the second known portion refer to the same surface area
of color standard 830, which can include the same
colors or the same predetermined combination of colors.
Calibration is the same according to this aspect of the
invention, but verification includes an extra step.
The extra step is necessary because in this
constructive technique, the second known portion will
have verification measurement values) that can be
different from the verification's premeasured color
measurement value(s). Therefore, in order to verify
whether or not the color standard is an authorized
standard of predetermined specification and to verify
that the calibration of the color measuring instrument
is according to a predetermined specification according
to this aspect of the invention, computed color
measurement values must be calculated based on the
verification color measurement values) and those
computed values are compared with the verification's
premeasured color measurement value(s). The
calculation is simple because the verification's
premeasured color measurement values) would be related
to the verification color measurement values) by
predetermined differential color measurement value(s).
The computed color measurement values) can be the sum
of or difference between the verification color
measurement values) and the predetermined differential
color measurement value(s).
Therefore, the step of determining that the
verification color measurement values) is
substantially equal to the verification's premeasured
color measurement values) can include (1) calculating
computed color measurement values) based on the
verification color measurement values) and (2)
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
- 39 -
determining that the computed color measurement
values) are substantially equal to the verification's
premeasured color measurement value(s).
As in the case of the physical masking
techniques described above, the known portion measured
during the calibration and verification steps in this
constructive masking technique can be any known portion
on the standard surface, and can include a first color,
a second color, or a predetermined combination of a
first color and a second color. When standard 830 has
additional colors disposed thereon, the known portion
can include those additional colors as well.
As described above, the computed color
measurement values) can be calculated based on the
verification color measurement value(s). In one
embodiment, the computed color measurement values) can
be obtained by adding or subtracting predetermined
differential color measurement values) to the
verification color measurement value(s). For example,
when the known portion measured during verification is
a portion that consists essentially of the first color,
the predetermined differential color measurement
values) can be based on the verification's premeasured
color measurement value(s). If the verification's
predetermined coloration's premeasured color
measurement values) correspond to a combination of the
first and second colors, then the predetermined
differential color measurement values) would simply
correspond to the contribution of the second color,
that is, the "difference" between the contribution of
the first color and the contribution of the combination
of the first and second colors.
In another embodiment according to this
invention, the known portion measured during
verification is a portion that consists essentially of
CA 02315183 2000-06-14
VIVO 99/32861 PCTlUS98/27070
- 40 -
the second color. In that case, the predetermined
differential color measurement values) would also be
based on the verification's premeasured color
measurement value(s). However, if the verification's
premeasured color measurement values) correspond to a
combination of the first and second colors, then the
predetermined differential color measurement values)
would simply correspond to~the contribution of the
first color, that is, the "difference" between the
contribution of the second color and the contribution
of the combination of the first and second colors.
In a preferred embodiment, the known portion
measured in the verification step includes a
predetermined combination of the first color and the
second color. Then, if the verification's premeasured
color measurement values) corresponds to a first
color, the predetermined differential color measurement
values) would simply correspond to the contribution of
the second color -- the "difference" between the
contribution of the first color and the contribution of
the predetermined combination of the first and second
colors.
According to another embodiment of this
invention, FIGS. 9 and 10 show calibration and
verification apparatus 900. FIG. 9 is an exploded
perspective view of apparatus 900 and FIG. 10 is an
assembled perspective view of apparatus 900.
Apparatus 900 includes release liner 910, sanitary
layer 920, photosensitive layer 930, color
standard 940, and cap 950. As discussed more fully
below, while release liner 910, sanitary layer 920, and
cap 950 are preferred components of apparatus 900, they
are optional according to this invention.
Release liner 910 has first surface 912,
which faces downward in FIG. 9, and second surface 914,
CA 02315183 2000-06-14
VNO 99/32861 PCT/US98/Z7070
- 41 -
which faces upward in FIG. 9. Preferably, first
surface 912 of release liner 910 attaches to distal
surface 962 of color measuring instrument head 960,
which includes round window 963 through which color
measurements are made. Release liner 910 is preferably
optically opaque to prevent a photosensitive surface of
layer 930 from being exposed to sufficient
electromagnetic radiation to expose it enough to change
its color substantially before apparatus 900 is used.
Sanitary layer 920 has first surface 922,
which faces downward in FIG. 9, and second surface 924,
which faces upward in FIG. 9. Sanitary layer 920 has
first optically transparent aperture 926, such as a
hole, for exposing photosensitive layer 930 and color
standard 940 when used as described below. Second
surface 914 of release liner 910 can be attached to
first surface 922 of sanitary layer 920 with an
adhesive, or any other conventional means. It will be
appreciated that while release liner 910 and sanitary
layer 920 are attached, they can be separated as
desired. For example, when liner 910 and layer 920 are
attached to each other by an adhesive, they can be
separated without destroying sanitary layer 920 by
simply pulling tab 918 of release liner 910.
Photosensitive layer 930 has first
surface 932, which faces downward in FIG. 9, and second
surface 934, which faces upward in FIG. 9. Layer 930
is preferably mounted so that first surface 932 faces
second surface 924 of sanitary layer 920. First
surface 932 has at least a first photosensitive color
disposed thereon. Also, layer 930 has second optically
transparent aperture 936 that has a cross-sectional
area that is smaller than the cross-sectional area of
first optically transparent aperture 926.
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
- 42 -
Preferably, region 935 of layer 930 changes
color in a known way when exposed to a predetermined
dose of light. One example of a photosensitive paper
that can be used in accordance with this invention is
sold under the name "polycontrast 3RC E," which is
available from the Eastman Kodak Company, of Rochester,
New York. In this case, the region of photosensitive
layer exposed to visible light will darken a known
amount when the it is exposed to a predetermined dose
of light.
Color standard 940 has first surface 942,
which faces downward in FIG. 9, and second surface 944,
which faces upward in FIG. 9. Layer 940 is mounted so
that its first surface 942 is facing second surface 934
of layer 930. Furthermore, standard 940 is mounted so
that region 946 of first surface 942 is adjacent second
aperture 936. In this way, region 946 can measured
through second aperture 936 during operation.
Region 935 of photosensitive layer 930 preferably
changes color in a known way when exposed to a
predetermined dose of light, such as a predetermined
number of flashes of light emitted by a color measuring
instrument. It will be appreciated that first
surface 942 of standard 940 can be attached to second
surface 934 of layer 930 with adhesive. Second
surface 924 of sanitary layer 920 can be removably
attached to first surface 942 of layer 930 with
adhesive.
The sizes of various components used in
accordance with this invention are now described. The
area within aperture 926 is preferably larger than the
area within window 963 so that inner rim 927 of
layer 920 does not interfere with color measurements.
Also, the area within aperture 936 is preferably
smaller than the area within window 963 to ensure that
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
- 43 -
at least a portion of photosensitive region 935 is
exposed during color measurements. To ensure that a
light-tight seal is formed when layer 930 and
standard 940 are combined, the surface area of color
standard 940 is preferably at least as large as the .
area within aperture 936. And, to ensure accurate
calibration and verification, the surface area of
region 946 is preferably larger than the surface area
of region 935.
Optional cap 950 has inner surface 952, which
faces downward in FIG. 9, and is adapted to
substantially fit over at least second aperture 936,
which further provides an opaque back surface for the
color standard.
A method according to this invention for
calibrating and verifying via calibration and
verification apparatus 900 is now described. To some
extent the method has already been discussed above, so
the description here is somewhat abbreviated. After
mounting the apparatus on the instrument so that the
first surface of the sanitary layer faces a head of the
instrument; the method includes calibrating the
instrument with the apparatus; exposing at least the
second region with light; and verifying that the color
standard used in calibration is an authorized color
standard of the predetermined specification and that
the calibration of the color measurement instrument has
achieved predetermined specified results.
When the apparatus 900 includes release
liner 910, the method also includes removing the
release liner from the first surface of the sanitary
layer before mounting the apparatus.
When apparatus 900 is mounted to instrument
head 960, it is preferably temporarily attached, such
as via an adhesive or by some other fastening means,
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
- 44 -
such as a clip. Regardless of the particular fastening
means used to attach apparatus 900 to head 960, the
individual layers should be easily removable as
described herein.
During the calibrating step, unexposed color
measurement values) of a first known portion,
including the photosensitive region, is determined. As
used herein, unexposed color measurement values) is
the color measurement values) that characterizes the
portion before being exposed to a sufficient dose of
electromagnetic energy to expose it and change its
color substantially in the exposing step.
In the exposing step, the known dose of
electromagnetic energy can be provided by one or more
flashes emitted by the color measuring instrument.
Color measurements can be made at any time during the
calibration and verification procedure, including after
any number of flashes, as a further check that the
color standard being used is unexposed.
In the verifying step, exposed color
measurement values) of a second known portion is
determined. The second known portion can be identical
to the first known portion. As used herein, exposed
color measurement values) is the color measurement
values) that characterizes the color of the second
known portion after being exposed to sufficient
electromagnetic energy in the exposing step to expose
it and substantially change its color.
If it is determined that the color standard
being used to calibrate a color measuring instrument is
unexposed, the instrument can be programmed to continue
the calibration and verification procedure. On the
other hand, if it is determined that the color standard
being used to calibrate a color measuring instrument
has been exposed prior to a calibration or becomes
CA 02315183 2000-06-14
VVO 99/32861 PCTNS98/27070
- 45 -
exposed other than in a known way with a predetermined
dose of light, the instrument can be programmed to
discontinue the calibration and verification procedure,
such as by rejecting the color standard.
According to yet another embodiment of this.
invention, FIGS. 11 and 12 show calibration and
verification apparatus 1000. FIG. 11 is an exploded
perspective view of apparatus 1000 and FIG. 12 is an
assembled perspective view of apparatus 1000.
Apparatus 1000 includes release liner 1010, sanitary
layer 1020, color standard 1030, and photosensitive
layer 1040. A cap (not shown in FIGS. 11 and 12) can
also be used according to this embodiment of the
invention, but is optional. Also, while release
liner 1010 and sanitary layer 1020 are preferred
components of apparatus 1000, they are also optional
according to this invention.
Release liner 1010 has first surface 1012,
which faces downward in FIG. 11, and second
surface 1014, which faces upward in FIG. 11.
Preferably, first surface 1012 of release liner 1010
attaches to distal surface 1062 of color measuring
instrument head 1060, which includes round window 1063
through which color measurements are made. Like
release liner 910, 1010 is preferably substantially
optically opaque, to prevent photosensitive surface of
layer 1040 from being exposed to electromagnetic
radiation before calibrating a color measuring
instrument with apparatus 1000.
Sanitary layer 1020 has first surface 1022,
which faces downward in FIG. 11, and second
surface 1024, which faces upward in FIG. 10. Sanitary
layer 1020 has optically transparent aperture 1026,
such as a hole or transparent film, for exposing color
standard 1030 and photosensitive layer 1040 when used
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/Z7070
- 46 -
as described below. Second surface 1014 of release
liner 910 can be attached to first surface 1022 of
sanitary layer 1020 with an adhesive, or any other
conventional means. It will be appreciated that while
release liner 1010 and sanitary layer 1020 are
attached, they can be separated if and when desired.
For example, when liner 1010 and layer 1020 are
attached to each other by an adhesive, they can be
separated without destroying sanitary layer 1020 by
simply pulling tab 1018 of release liner 1010.
Color standard 1030 has first surface 1032,
which faces downward in FIG. 11, and second
surface 1034, which faces upward in FIG. 11.
Standard 1030 is mounted so that its first surface 1032
faces second surface 1024 of sanitary layer 1020.
Furthermore, standard 1030 is mounted so that
region 1036 of first surface 1032 is adjacent
aperture 1026. In this way, region 1036 can be exposed
to light though aperture 1026 during operation. Like
first surface 932 of color standard 930, the color of
first surface 1032 of color standard 1030 should at
least have a first color disposed thereon which is
characterized by a first predetermined coloration
having premeasured color measurement value(s).
Photosensitive layer 1040 has first
surface 1042, which faces downward in FIG. 11, and
second surface 1044, which faces upward in FIG. 11.
Layer 1040 is preferably mounted so that first
surface 1042, which includes a photosensitive region,
faces second surfaces 1024 and 1034. At least a part
of photosensitive region 1046 must be exposed during
the exposing step. In this embodiment, the part of
photosensitive region 1046 that is exposed is annular.
As already discussed above with respect to
apparatus 900, photosensitive portion 1046 of
CA 02315183 2000-06-14
WO 99/32861 PCT1US98/27070
- 47 -
layer 1040 changes color in a known way when exposed to
a predetermined dose of visible light. Layer 1040 can
have tab portion 1048 -for a user to grasp when removal
is desired.
Second surface 1024 of sanitary layer 1020.
can be removably attached to at least one of first
surfaces 1032 and 1042. When a sanitary layer is not
used in accordance with this invention, the technician
calibrating the instrument can sterilize the skin,
and/or the color measuring instrument head, with a
sterilizing agent (e. g., alcohol).
The sizes of various components used in
accordance with this invention are now described. The
area within aperture 1026 may be larger than the area
within window 1063 so that inner rim 1029 of layer 1020
does not interfere with color measurements. Also, to
ensure that at least a portion of photosensitive
region 1046 is exposed during color measurements, the
surface area of region 1036 may be smaller than the
area within aperture 1026. And finally, to ensure
accurate calibration and verification; the surface area
of region 1036 may be larger than the surface area of
region 1046.
According to a further embodiment of this
invention, FIGS. 13-15 show calibration and
verification apparatus 1100. As shown best in FIGS. 13
and 14, apparatus 1100 can include photosensitive
layer 1110, color standard 1120, and release
liner 1130.
Photosensitive layer 1110 has first
surface 1112, second surface 1114, and an optically
transparent aperture 1116. First surface 1112 has at
least a first region that is photosensitive. Second
surface 1114 is preferably attached to annular
portion 1128 of first surface 1122 with any
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
- 48 -
conventional adhesive. Region 1117 of first
surface 1112 preferably changes color in a known way
when exposed to a predEtermined dose of light. In
particular, that region preferably changes color in a
known amount (such as by darkening or lightening it)
when region 1117 is exposed to a predetermined dose of
visible light. As shown in FIG. 15, region 1117 can be
annular.
Color standard 1120 has first surface 1122
and second surface 1124. First surface 1122 is mounted
so that it faces second surface 1114 of layer 1110 and
so that first portion 1126 of standard 1120 is adjacent
optically transparent aperture 1116. First
surface 1112 can have one or more different colors
characterized by predetermined coloration having
premeasured color measurement value(s). A sanitary
layer (not shown) can also be included to prevent
transmission of germs and such between patients as
explained above and shown in FIGS. 9-12, for example.
Second surface 1134 of release liner 1130 is
preferably releasably mounted so that it faces first
surface 1112 in such a way that it prevents light from
becoming incident on annular region 1117 of
photosensitive layer 1110 when liner 1130 is attached.
To ensure accurate calibration and verification, the
surface area of region 1117 is preferably smaller than
region 1126 and region 1126 is preferably centrally
located. Therefore, release liner 1130 is preferably
substantially opaque to visible light and forms a light
tight seal with photosensitive 1120, such as with a
releasable adhesive. Also, release liner 1130 can also
include tab 1136 so that a user can easily remove
liner 1130 from photosensitive layer 1110 and color
standard 1120 before calibration or verification.
Apparatus 1100 can further include a cap (not shown).
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
- 49 -
According to a another embodiment of this
invention, FIGS. 16-18 show calibration and
verification apparatus 1200. As shown best in FIGS. 16
and 17, apparatus 1200 can include color standard 1210
and release liner 1230. Apparatus 1200 is essentially
the same as apparatus 1100, except that apparatus 1100
includes a color standard with an integrated
photosensitive portion.
Color standard 1210 has surface 1211 with at
least first region 1212 and second region 1214. First
region 1212 has at least a first color characterized by
a first predetermined coloration having premeasured
color measurement value(s). First region 1212 of
surface 1211 can have two or more different colors,
including a second color characterized by a second
predetermined coloration having premeasured color
measurement value(s). Second region 1214 is
photosensitive. To ensure accurate calibration and
verification, the surface area of region 1214 is
preferably smaller than region 1212 and region 1212 is
preferably centrally located. A sanitary layer (not
shown) can also be included to prevent transmission of
germs and such between patients as explained above and
shown in FIGS. 9-12, for example.
Release liner 1230 is preferably releasably
mounted so that it faces surface 1211 of color
standard 1210 in such a way that it prevents light from
becoming incident on second portion 1214 when
liner 1230 is mounted or attached to color
standard 1210. Therefore, release liner 1230 is
preferably substantially opaque to visible light and
forms a light tight seal with color standard 1210 on
first portion 1214. Also, release liner 1230 can also
include tab 1236 so that a user can easily remove
liner 1230 from color standard 1210 before calibration
CA 02315183 2000-06-14
WO 99/32861 PCTNS98/27070
- 50 -
or verification. Apparatus 1200 can include a cap (not
shown) for handling color standard 1210 during
calibration and verification.
According to a further embodiment of this
invention, FIGS. 19-21 show calibration and
verification apparatus 1300. As shown best in FIGS. 19
and 20, apparatus 1300 can include photosensitive
layer 1310, color standard 1320, and release
liner 1330.
Photosensitive layer 1310 has first
surface 1312, second surface 1314. First surface 1312
has at least first region 1315 that is photosensitive.
Color standard 1320 has first surface 1322
and second surface 1324. Second surface 1324 is
attached to first portion 1316 of layer 1310. In this
way, first surface 1322 is mounted so that it faces the
same direction as first surface 1312. This arrangement
allows a simultaneous color measurement, if desired.
First surface 1322 can have one or more colors
characterized by predetermined colorations having
premeasured color measurement value(s). To ensure
accurate calibration and verification, the surface area
of annular region 1315 is preferably smaller, and most
preferably substantially smaller, than region 1322 and
region 1322 is preferably centrally located. It will
be appreciated that photosensitive region can be any
shape and therefore need not be annular.
A sanitary layer (not shown) can also be
releasably attached to a portion of first surface 1312
of color standard 1310 to prevent transmission of genes
and such between patients as described above and shown
in FIGS. 9-12, for example.
As shown best in FIG. 19, second surface 1334
of release liner 1330 is preferably releasably mounted
so that it faces first surface 1312 of layer 1310 in
CA 02315183 2000-06-14
WO 99/32861 PCT/US98/27070
- 51 -
such a way that it blocks light from becoming incident
on region 1315 of photosensitive layer 1310 when
liner 1330 is attached.
Apparatus 1300 can also include a cap (not
shown). The use of a cap can help a user align
apparatus 1300 on the head of the color measuring
instrument, and provide a substantially opaque back
surface for the apparatus.
Thus, it is apparent that there has been
provided, in accordance with the invention, methods and
apparatus of color calibration and verification that
fully satisfies the objects, aims and advantages set
forth above. While the invention has been described in
conjunction with specific embodiments thereof, it is
evident that many alternatives, modifications and
variations will be apparent to those skilled in the art
and in light of the foregoing description.
Accordingly, it is intended to embrace all such
alternatives, modifications and variations as fall
within the spirit of the appended claims.
