Digital Camera Patent AbstractSystems, methodologies, media, and other embodiments associated
with color measuring are described. One exemplary system embodiment
includes a spectrophotometer, one or more light sources for illuminating
an interior of the spectrophotometer, and a digital camera configured
at a port of the spectrophotometer and being configured to measure
light components from a sample. In the present invention, segmentation
logic is provided for the spectrophotometer that is configured to
employ computational image segmentation to characterize specular
reflection from a sample and to characterize a selected patch or
portion from the test sample, such as a selected color in a multicolor
pattern. In accordance with the present invention, the spectrophotometer
and the included digital camera may be color-characterized in situ.
Digital Camera Patent ClaimsWhat is claimed is:
1. A method for color measuring, comprising: collecting light signals
from an illuminated sample using a multi-segmented detector configured
to capture spatial variations in a color of the sample; dividing
a total signal received by said detector into groups of one or more
of said segments, said groups representing different spatial regions
of said illuminated sample; and measuring color information for
one or more of said divided groups independently of a remainder
of said divided groups, in order to produce a color measurement
for said one or more of said divided groups.
2. The method of claim 1, wherein said multi-segmented detector
comprises a digital camera.
3. The method of claim 2, wherein said segments comprise pixels.
4. The method of claim 1, wherein said groups are formed by segments
receiving signals having similar color properties.
5. The method of claim 1, further comprising color-characterizing
said multi-segmented detector with standard test samples.
6. An apparatus for color measuring, comprising: a spectrophotometer;
at least one light source for illuminating an interior of the spectrophotometer
and at least one sample; and a multi-segmented detector configured
at a port of the spectrophotometer and being adapted to measure
light components from said at least one sample and to capture spatial
variations in the color of the sample.
7. The apparatus of claim 6, wherein said spectrophotometer comprises
an integrating-sphere.
8. The apparatus of claim 6, wherein said multi-segmented detector
comprises a digital camera.
9. The Apparatus of claim 6, wherein one of said at least one light
sources is configured to directly illuminate the at least one sample,
and the at least one sample and the multi-segmented detector are
apposed to a direction of the light from said one of said at least
one light source to form a specular path connecting the light, the
sample, and the multi-segmented detector.
10. The apparatus in claim 6, wherein one of said at least one
light sources is configured to diffusely illuminate the sample.
11. An apparatus for color measuring, comprising: a spectrophotometer;
at least one light source for illuminating an interior of the spectrophotometer
and at least one sample; a multi-segmented detector configured at
a part of the spectrophotometer and being adapted to measure light
components from said at least one sample; and at least one photometer
for measuring light components from standard test samples for use
in color-characterizing at least one of said multi-segmented detector
and said spectrophotometer.
12. An apparatus for color measuring, comprising: a spectrophotometer;
at least one light source for illuminating an interior of the spectrophotometer
and at least one sample; and a multi-segmented detector configured
at a port of the spectrophotometer and being adapted to measure
light components from said at least one sample, wherein one of said
at least one light sources is configured to directly illuminate
the at least one sample, and the at least one sample and the multi-segmented
detector are opposed to a direction of the light from said one of
said at least one light source to form a specular path connecting
the light, the sample, and the multi-segmented detector, and wherein
said one of said at least one light sources comprises a light projector
that projects an illuminated grid image onto the sample which is
captured by the multi-segmented detector.
13. The apparatus of claim 12, wherein said captured illuminated
grid image is used to determine if a sample port of said spectrophotometer
is opened or closed, and if open, the size of the opening.
14. A computer-readable medium configured to provide processor
executable instructions operable to perform a method, the method
comprising: illuminating a test sample within an integrating sphere;
measuring optical signals received from the test sample; and color-characterizing
a multi-segmented detector configured for capturing spatial variations
in a color of the test sample, based on the optical signals received
where the multi-segmented detector is operably connected to the
integrating sphere.
15. A computer-readable medium configured to provide processor
executable instructions operable to perform a method, the method
comprising: receiving an image generated by a multi-segmented detector
from measured light signals from a color sample, the multi-segmented
detector being configured to capture spatial variations in a color
of the sample; selecting a region of interest from within the image;
and measuring color information for the selected region of interest
independently from other areas of the image, in order to produce
a color measurement for the selected region of interest.
16. The computer-readable medium of claim 15 where the processor
executable instructions are embodied as a graphical user interface.
17. A color measuring system, comprising: a spectrophotometer for
providing and directing light signals from a sample; at least one
light source for illuminating an interior of said spectrophotometer
and said sample; and a multi-segmented detector configured in a
port of the spectrophotometer and being configured to measure the
light signals from the sample and to capture spatial variations
in the color of the sample; selection logic configured to enable
a region of interest to be selected from the measured light signals;
and analysis logic adapted to determine color information from the
region of interest separately from other measured light signals.
18. The color measuring system of claim 17, further comprising:
calibration logic configured to calibrate or characterize the multi-segmented
detector using the measured light signals and known color values
for the sample.
19. The color measuring system of claim 17, wherein said multi-segmented
detector is adapted to measure optical radiation from the sample
and generate image data of the sample and to communicate the image
data to a computing device using wireless communication.
20. A color measuring system, comprising: a spectrophotometer for
providing and directing light signals from a sample; at least one
light source for illuminating an interior of said spectrophotometer
and said sample; a multi-segmented detector configured in a port
of the spectrophotometer and being configured to measure the light
signals from the sample; selection logic configured to enable a
region of interest to be selected from the measured light signals;
analysis logic adapted to determine color information from the region
of interest separately from other measured light signals; and logic
configured to determine a size of an aperture of a sample port using
the measured light signals from the multi-segmented detector.
21. A color measuring system, comprising: a spectrophotometer for
providing and directing light signals from a sample; at least one
light source for illuminating an interior of said spectrophotometer
and said sample; a multi-segmented detector configured in a port
of the spectrophotometer and being configured to measure the light
signals from the sample; selection logic configured to enable a
region of interest to be selected from the measured light signals;
and analysis logic adapted to determine color information from the
region of interest separately from other measured light signals,
wherein said color measuring system comprises a plurality of modes
of operation including at least a spectrophotometer mode, a mode
used to characterize the specular-reflected component of a material,
a mode used to image a variegated sample and a mode used to perform
shape measurement of a three-dimensional sample.
22. The color measuring system of claim 21, wherein said at least
one light source comprises at least two light sources and a light
projector that projects an illuminated grid image onto the sample
and wherein said color measuring system switches between modes of
operation by activating and deactivating specific ones of said light
sources. Digital Camera Patent DescriptionBACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to color measuring devices
and more specifically to systems, methods, computer-readable media,
and other devices associated with measuring of color of a sample
under test using a spectrophotometer or other color measuring device.
2. Description of the Related Art
A specular (mirror-path, or gloss) component of light reflecting
from a material sample is often different in color from the body-reflection
(perhaps matte) component. For example, in dielectric materials,
the specularly-reflected light has the same relative spectrum as
that of the incident illumination. Characterizing the color of a
sample through a spectrophotometer (for example, an instrument based
on an integrating sphere) can be designed to separate the specular
from the matte component of reflection. That task is not difficult
for smooth samples: Standard practice with integrating spheres simply
uses a closable port that excludes or includes the light within
a small incidence angle of the mirror path to the exit port of the
device (the port through which the reflected light is recorded by
the spectrophotometer). However, for rough samples (and particularly
for textiles) such practice does not truly separate out the specular
component: The specular reflection arises from elsewhere on the
sphere than the specular port. Characterizing the geometry of the
specular component of reflection through means other than the simple
opening or closing of a hole in the integrating sphere may be useful.
A user may wish to measure the reflectance properties of a sample
of material in an industrial "batch" and compare those
properties with a standard sample. The "batch" may incorporate
the material in a pattern (e.g., a textile pattern), whereas the
standard is ensured to be calorimetrically uniform over its entire
surface. A spectrophotometer can give accurate reflectance values
for a sample that is spatially uniform (such as a calibrating tile).
However, it is difficult to measure the reflectance spectrum of
a part of a patterned material. The sample port of the spectrophotometer
must be sized and shaped specifically for the part of the material
specimen that is to be measured. Such adaptation may produce its
own artifacts of measurement (e.g., depth of the mask next to the
small area reduces the illumination to that area).
An integrating-sphere spectrophotometer can have several automatic
mechanisms that determine the aperture of the sample port, whether
the sample port door is open or closed, and the position of the
sample. All these mechanisms are quite expensive in current implementations.
Also, the spectrophotometer by itself does not allow viewing and
adjustment of the sample once the sample is readied for measurement.
SUMMARY OF THE INVENTION
Color measuring systems, methods, computer-readable media, graphical
user interfaces, and other embodiments associated with color measuring
are provided herein. In one embodiment of the present invention,
a color measuring system includes an integrating-sphere spectrophotometer
combined with a camera that may be color-characterized in situ.
The spectrophotometer includes a calibrated and/or color-characterized
video camera configured to measure quantitatively such image characteristics
as the specular component of a sample's reflectance, the reflectance
of a small, selected part of a variegated pattern from the sample,
and other color characterization functions.
In an alternate embodiment of the present invention, a spectrophotometer
is provided that is configured with a digital camera and one or
more secondary light sources configured to color-characterize the
camera with standard material samples/test samples in situ. In the
present invention, segmentation logic is provided for the spectrophotometer
that is configured to employ computational image segmentation to
characterize specular reflection from a uniform sample and to characterize
a selected patch or portion from the test sample, such as a selected
color in a multicolor pattern. In one embodiment of the present
invention, the segmentation logic is implemented as software and
is provided on any desired computer-readable medium. The segmentation
logic may be part of the processing system of the spectrophotometer
and/or may be part of a computing device operably connected to the
spectrophotometer.
In an embodiment of a color measuring system of the present invention
implemented for measuring a sample having a non-uniform pattern,
image segmentation logic may be configured to automatically segment
the camera image into uniformly colored areas, which may be separately
characterized. The image segmentation logic associated with the
camera may also be used to determine the state of opening of a sample
port, the aperture of the port, and the position of the sample.
BRIEF DESCRIPTION OF THE DRAWINGS
So that the manner in which the above recited features of the present
invention can be understood in detail, a more particular description
of the invention, briefly summarized above, may be had by reference
to embodiments, some of which are illustrated in the appended drawings.
It is to be noted, however, that the appended drawings illustrate
only typical embodiments of this invention and are therefore not
to be considered limiting of its scope, for the invention may admit
to other equally effective embodiments. Furthermore, elements may
not be drawn to scale.
FIG. 1 depicts a high level block diagram of a color measuring
system in accordance with an embodiment the present invention.
FIG. 2 depicts a high level block diagram of a second color measuring
system in accordance with an alternate embodiment of the present
invention.
FIG. 3 depicts an embodiment of a method of the present invention
for segmenting a region of interest from an image captured in accordance
with an embodiment of the present invention.
FIG. 4 depicts a three dimensional diagram of an integrating sphere
and camera combination color measuring system in accordance with
an alternate embodiment of the present invention.
FIG. 5 depicts a high level block diagram of a computing device
suitable for use in the color measuring systems of FIGS. 1, 2 and
4 for performing the methods and operations of the present invention
in accordance with an embodiment of the present invention.
To facilitate understanding, identical reference numerals have
been used, where possible, to designate identical elements that
are common to the figures.
DETAILED DESCRIPTION
"Logic", as used herein, includes but is not limited
to hardware, firmware, software and/or combinations of each to perform
a function(s) or an action(s), and/or to cause a function or action
from another logic, method, and/or system. For example, based on
a desired application or need, logic may include a software controlled
microprocessor, discrete logic like an application specific integrated
circuit (ASIC), a programmed logic device, a memory device containing
instructions, or the like. Logic may include one or more gates,
combinations of gates, or other circuit components. Logic may also
be fully embodied as software. Where multiple logical logics are
described, it may be possible to incorporate the multiple logical
logics into one physical logic. Similarly, where a single logical
logic is described, it may be possible to distribute that single
logical logic between multiple physical logics.
An "operable connection", or a connection by which entities
are "operably connected", is one in which signals, physical
communications, and/or logical communications may be sent and/or
received. Typically, an operable connection includes a physical
interface, an electrical interface, and/or a data interface, but
it is to be noted that an operable connection may include differing
combinations of these or other types of connections sufficient to
allow operable control. For example, two entities can be operably
connected by being able to communicate signals to each other directly
or through one or more intermediate entities like a processor, operating
system, a logic, software, or other entity. Logical and/or physical
communication channels can be used to create an operable connection.
"Signal", as used herein, includes but is not limited
to one or more electrical or optical signals, analog or digital
signals, data, one or more computer or processor instructions, messages,
a bit or bit stream, or other means that can be received, transmitted
and/or detected.
"Software", as used herein, includes but is not limited
to, one or more computer or processor instructions that can be read,
interpreted, compiled, and/or executed and that cause a computer,
processor, or other electronic device to perform functions, actions
and/or behave in a desired manner. The instructions may be embodied
in various forms like routines, algorithms, modules, methods, threads,
and/or programs including separate applications or code from dynamically
linked libraries. Software may also be implemented in a variety
of executable and/or loadable forms including, but not limited to,
a stand-alone program, a function call (local and/or remote), a
servelet, an applet, instructions stored in a memory, part of an
operating system or other types of executable instructions. It will
be appreciated by one of ordinary skill in the art that the form
of software may be dependent on, for example, requirements of a
desired application, the environment in which it runs, and/or the
desires of a designer/programmer or the like. It will also be appreciated
that computer-readable and/or executable instructions can be located
in one logic and/or distributed between two or more communicating,
co-operating, and/or parallel processing logics and thus can be
loaded and/or executed in serial, parallel, massively parallel and
other manners.
Suitable software for implementing the various components of the
example systems and methods described herein include programming
languages and tools like Java, Pascal, C#, C++, C, CGI, Perl, SQL,
APIs, SDKs, assembly, firmware, microcode, and/or other languages
and tools. Software, whether an entire system or a component of
a system, may be embodied as an article of manufacture and maintained
or provided as part of a computer-readable medium as defined previously.
Another form of the software may include signals that transmit program
code of the software to a recipient over a network or other communication
medium. Thus, in one example, a computer-readable medium has a form
of signals that represent the software/firmware as it is downloaded
from a web server to a user. In another example, the computer-readable
medium has a form of the software/firmware as it is maintained on
the web server. Other forms may also be used.
FIG. 1 depicts a high level block diagram of a color measuring
system in accordance with an embodiment the present invention. The
color measuring system of FIG. 1 illustratively comprises an integrating-sphere
spectrophotometer 100 operably connected to a multi-segment detector
(illustratively a camera) 105. The color measuring system of FIG.
1 further comprises a light source 110, a sample 115, a specular
port 125 of the integrating-sphere spectrophotometer 100 and a computing
device 135. For simplicity, other components such as additional
light sources, baffles, ports, sensors, and the like are not shown
in the integrating-sphere spectrophotometer 100 but will be readily
understood by those skilled in the art as being available features.
One example of a color measuring device can be as described in pending
U.S. Provisional Patent Application Ser. No. 60/450,311, filed Feb.
27, 2003, title "Spectrophotometer Color Measurement and Diagnostics
Over the Web" which is incorporated herein by reference in
its entirety. The camera 105 can be for example, a digital camera,
a video camera, a CCD camera, other types of cameras, and/or combinations
of these, that is capable of observing and providing signal data
that represents color from a sample object under test. The camera
105 can be an independently operable device like a standard digital
camera.
In one embodiment, a light source 110 is used to illuminate the
sample 115 positioned in a sample port (not shown) of the integrating
sphere spectrophotometer 100. The camera 105 is positioned to receive
reflected light from the sample 115 from an opposite angle from
a normal 120 to the sample as the light source 110 (e.g. at the
specular angle). A specular port 125 that can open or close is located
on the integrating-sphere spectrophotometer 100 in front of the
described location of the camera in order to control specular reflection.
The camera 105 is operably connected by being mounted to the sphere
100 at the specular port 125, mounted adjacent to the port 125,
or mounted outside the sphere 100 but configured to receive light
from the port 125.
The camera 105 is configured to measure light properties from the
sample 115. For example, the camera 105 may be color characterized
and used to measure a reflected component (e.g. gloss component)
from the sample 115. The camera 105 is configured to generate image
data 130 in the form of signals representing the received light.
In various embodiments, the camera 105 may include data transceiver
logic and one or more communication ports that can establish a communication
link/computer communication with the computing device 135 (e.g.
wireless, wired, or other) to which the image data 130 may be transmitted.
In one embodiment of the present invention, the camera 105 may be
Bluetooth enabled with a Bluetooth compatible transceiver and appropriate
communication protocol logic. In this configuration, the camera
105 may transmit the image data 130 to another Bluetooth enabled
device such as the computing device 135. The image data 130 may
then be processed by the computing device 135.
In the embodiment of FIG. 1, the computing device 135 comprises
an analysis logic block 140 that, in one embodiment, may be an image
processing application embodied in software. The computing device
135 of FIG. 1 further comprises a user interface 150, a segmentation
logic block and a selection logic block 155. The analysis logic
140 is configured to receive the image data 130, process the data
in any desired way, and provide results of the analysis, such as
color information, characteristics, or other properties of the sample
115. The output may be configured in any desired signal form such
as analyzed image data 145. Thus, with the camera 105 positioned
in at the specular port 125 and with the image processing application
140, the system is able to characterize a geometry and magnitude
of the specular component of the sample's reflection based on the
measured values from the camera 105.
In one embodiment of the present invention, the analysis logic
140 is configured to allow a user to dynamically select a portion
of the image data 130 in real-time and the selected portion is analyzed
for color information. For example, suppose the sample 115 includes
a multi-color pattern like plaid. The camera 105 may generate an
image or picture of the sample 115 and communicate the picture as
the image data 130 to the computing device 135 for processing. Analysis
of the image data 130 as a whole, in this case, would probably not
provide useful color information because the multiple colors would
cause the analysis to provide an average color value of all colors.
However, an analysis of individual colors from the sample may be
desired to determine specific color data.
The analysis logic 140 is configured with a graphical user interface
150 that allows a user to view the image data 130 (e.g. the picture
of the sample) and to select a region of interest for analysis,
and/or other image processing options. For example in one embodiment
of the present invention, the graphical user interface 150 may be
implemented in software and configured to cause the computing device
135 to display the image data 130 on a display (not shown). Logic
operations of the present invention are configured to allow a user
to make selections, input data, request data, and otherwise interact
with the image data 130, the analysis logic 140, and/or other component
of the computing device 135.
The selection logic 155 of the computing device 135 of FIG. 1 is
configured to enable the user to select a region of interest from
the image for color analysis or other processing. The region of
interest may be selected pixels or an area that corresponds to an
individual color from the multicolor sample. An input device such
as a mouse, pointer, or the like may be configured to allow a user
to select the region of interest. The pixel information associated
with the selected region is then analyzed individually and separately
from the rest of the image data 130 to provide color information
for the selected region. For example, the segmentation logic 160
of the computing device 135 of FIG. 1 is provided to segment the
image data 130 based on the selected region of interest and pull
out the corresponding pixel information for analysis. By repeating
this process for other areas having different colors in the multicolor
sample, individual color information (e.g. pixel color values) may
be obtained for each different color. Although the color measuring
system of FIG. 1 depicts a camera for measuring light properties
of an illuminated sample, it will be appreciated by those skilled
in the art and informed by the teachings of the present invention,
that other light measuring devices, such as a group of photodiodes,
photodetectors, and/or other light detecting instruments, may be
used in place of the camera depicted in the color measuring system
of FIG. 1.
FIG. 2 depicts a high level block diagram of a second color measuring
system in accordance with an alternate embodiment of the present
invention. The measuring system of FIG. 2 is another example of
a color measuring system of the present invention including a calibration
system for the integrating-sphere spectrophotometer 100 and the
camera 105. In the color measuring system of FIG. 2, a calibration/characterization
logic 200 is provided in the computing device 135 to perform color
calibration/characterization for the integrating-sphere spectrophotometer
100, for the camera 105, or for both. In FIG. 2, the integrating-sphere
spectrophotometer 100 is depicted with a photometer 205 that is
configured to detect light from a sample exit port 210. The photometer
205 may include, for example, one or more photodetectors, photodiodes,
photomultiplier tubes, and/or other type of optical radiation detecting
device. Signals representing the detected light are transmitted
to the computing device 135 as sphere data 215. The integrating-sphere
spectrophotometer 100 also includes a diffuse light source 220 and
a flash light source 225, such as a Xenon light. In the embodiment
of the present invention of FIG. 2, the light sources 220 and 225
are positioned at the same port in the integrating-sphere spectrophotometer
100. One or more baffles (not shown) may be used to block a direct
illumination path from the light sources 220, 225 to the sample
115, the camera 105, and/or the photometer 205.
Using a set of color samples (e.g. color tiles) having known color
values 230, each color tile may be placed as the sample 115 and
measured with the sphere/camera combination in, for example, two
calibration modes. A first calibration mode is used to characterize
the camera 105 by illuminating the diffuse light 220 and measuring/reading
image signals with the camera 105 corresponding to the sample 115.
The image signals are communicated to the computing device 135 as
image data 130. The measured value (e.g. image data 130) for each
color tile is then compared to its corresponding known value 230
and a characterization offset is determined for that value. Repeating
this described procedure for multiple color tiles provides additional
characterization offset values and a characterization table, such
as a characterization look up table (LUT) 235, may generated for
the camera 105. Missing values within the LUT 235 may be generated
using any desired interpolation technique.
In a second calibration mode, using the same color tiles, light
properties from the inner sphere walls are also measured by the
photometer 205. The measured light properties may be used to generate
corresponding sphere data 215 that is provided to the computing
device 135. This may be performed by flashing the xenon light 225
and measuring the light within the integrating-sphere spectrophotometer
100. The calibration logic 200 compares the measured sphere data
215 with the known values 205 for the current color tile sample
115 and generates a calibration offset value. A calibration look
up table (LUT) 240 may be generated for the integrating-sphere spectrophotometer
100. Missing values may again be interpolated. In this manner, the
camera 105 is color characterized in situ and may use the same color
samples as used for the integrating-sphere spectrophotometer 100.
Thus, the camera 105 is color-characterized in situ at a port of
the integrating-sphere spectrophotometer 100. In alternate embodiments
of the present invention, the color measuring system of FIG. 2 may
switch between the two calibration modes for each different color
sample 115 used.
During an initial characterization/calibration, a large set of
samples may be used to calibrate the camera 105 and/or the integrating-sphere
spectrophotometer 100. Subsequently, a smaller sample set may be
used for daily calibration and/or calibration per use. Calibration
may also be performed periodically to compensate, for example, for
any camera color drift due to a change in temperature.
Although not shown, different light sources may be used for the
integrating-sphere spectrophotometer 100 and for the camera 105.
For example, the light source 110 may be positioned and used for
measuring a gloss component by the camera 105. A different light
source (not shown) may be positioned to provide diffuse illumination
within the integrating-sphere spectrophotometer 100. By measuring
diffuse light from the sample 115, the camera 105 is able to capture
spatial variations in the color of the sample 115. Another light
source (not shown) may then be provided as a high powered light
that may be intermittently flashed. One example of such a light
source is a Xenon lamp. In another embodiment, a light source (not
shown) may be provided at a 45 degrees offset to the axis of the
camera 105. The camera 105 is then able to simulate a 45/0 geometry
of the sample 115.
In the various embodiments of the present invention described above
implementing the image processing software 140, calibration logic
200 and the camera 105, the color measuring systems of the present
invention are able to characterize colored areas in a multicolored
sample, together with a combination of spectrophotometry and colorimetry
of a large uniform standard made of the same reflecting material,
to control the color in the multicolored sample and to make inferences
about the spectrum of reflectance based on the color.
FIG. 3 depicts an embodiment of a method of the present invention
for segmenting a region of interest from an image captured in accordance
with an embodiment of the present invention. While for purposes
of simplicity of explanation, the method 300 of FIG. 3 is depicted
and described as a series of blocks, it is to be appreciated that
the methodologies are not limited by the order of the blocks, as
some blocks may occur in different orders and/or concurrently with
other blocks from that shown and described. It will be appreciated
that the processes described in the series of blocks of the method
300 of FIG. 3 may be implemented using various programming approaches
like machine language, procedural, object oriented and/or artificial
intelligence techniques and the like.
The method 300 of FIG. 3 begins at step 310 by observing a sample
with a color measuring device and generating an image from the measured
sample. The method 300 proceeds to step 320.
At step 320, a region of interest, such as one or more pixels and/or
an area within the image, is selected. The method 300 then proceeds
to step 330.
At step 330, the region of interest selected in step 320 is segmented
and pixel values from the region are extracted. The method 300 then
proceeds to step 340.
At step 340, color values from extracted pixels are determined
independently from other areas of the image. The method 300 is then
exited.
In an alternate embodiment of the present invention, a method,
such as the method 300 of FIG. 3, for segmenting a region of interest
from an image captured in accordance with an embodiment of the present
invention further comprises illuminating a test sample within an
integrating sphere; measuring optical signals received from the
test sample with a digital camera operably connected to the integrating
sphere; and color-characterizing (or calibrating) the digital camera
based on the optical the measured signals as compared to known signal
values. In such an embodiment of the present invention, the digital
camera may be operably connected to an included integrating sphere
by being positioned at the location of a specular port or other
port of the integrating sphere.
FIG. 4 depicts a three dimensional diagram of an integrating-sphere
spectrophotometer 402 and digital camera 404 combination color measuring
system in accordance with an alternate embodiment of the present
invention. In the color measuring system 400 of FIG. 4, the integrating-sphere
spectrophotometer 402 illustratively comprises a variety of features
such as two baffles 410.sub.1-410.sub.2 (collectively baffles 410),
three light sources 420.sub.1-420.sub.3 (collectively light sources
420), and a plurality of ports, for example, a sample port 430,
a sample exit port 440, a specular port 450, and an illuminant port
460.
The color measuring system 400 of FIG. 4 is configured such that
the camera 404 is able to view a material sample-under-test through
the open specular port 450 of the integrating-sphere spectrophotometer
402. That is, in the color measuring system 400 of FIG. 4, the first
light source 420.sub.1 is positioned to illuminate a material sample
using the illuminant port 460. This geometry allows the camera 404
to capture the image of the geometry of the specular (e.g. mirror-reflection)
component of the light reflected from the material sample. The first
light source 420.sub.1 is shielded from directly illuminating the
camera, as the source 420.sub.1 lies outside of the integrating-sphere
spectrophotometer 402 and is operably connected to the integrating-sphere
spectrophotometer 402 by, for example, an opaque tube, or other
light transferring/transmitting device that does not allow light
to escape. The first light source 420.sub.1 is not flashed but turned
on for several seconds to allow enough time for the camera to capture
an image from the reflecting sample. The second light source 420.sub.2
is also not flashed and may be turned on and off independently of
the first light source 420.sub.1. The second light source 420.sub.2,
which may share an entry port with the third light source 420.sub.3,
is shielded by the baffles 410 from directly illuminating the sample
and from directly illuminating the specular port 450 and as such
the digital camera 404.
A color measuring system of the present invention, such as the
color measuring system 400 of FIG. 4, may be operated in various
modes in accordance with the present invention. For example, a color
measuring system of the present invention may be used as a normal
spectrophotometer, to characterize the footprint of a specular reflection,
to image a variegated sample, and to perform shape measurements
of a three-dimensional sample. The example modes described herein
are not to be interpreted as limiting in any way and more or less
modes may be configured, used, and implemented as desired in accordance
with the present invention.
In a normal spectrophotometer mode of a color measuring system
of the present invention, and referring to FIG. 4, a sample is diffusely
illuminated by the first light source 420.sub.1 (e.g., a Xenon flash
lamp), and a photometer (not depicted in FIG. 4) is mounted in or
operably connected to the sample exit port 440. The photometer at
the sample exit port 440 collects the reflected light from the sample
and analyzes it into narrow-band wavelength components. The photometer
may include photodiodes, photodetectors, or other type of optical
radiation detecting device. The digital camera 404 is not used in
the normal spectrophotometer operating mode. The specular port 450
may be either open or closed for the measurements made in this mode.
In a second mode of operation, a color measuring system of the
present invention may be used to characterize the specular-reflected
component of a material in the sample port 430 of the integrating-sphere
spectrophotometer 402 of the color measuring system of FIG. 4. In
this embodiment, the digital camera 404, installed at the open specular
port 450 (which is aimed at the sample), is used to separate the
specular from the matte component of reflection of the light from
the material illuminated by the second light source 420.sub.2 through
image processing among the color channels of the camera. For highly
chromatic samples, the image processing assigns a pixel as belonging
to the specular component if the pixel's ratios of red-to-green,
green-to-blue, and red-to-blue are sufficiently close to the corresponding
ratios for the incident illumination. For samples that do not display
sufficient spectral differences between specular and matte components,
a pixel is assigned specular status on the basis of its intensity,
I, compared with the intensity, I.sub.m, of the mirror-path pixel
and compared with the intensity, I.sub.o, of a pixel that is far
from the mirror-path pixel.
The intensity is a linear combination (with positive coefficients)
of red, green, and blue channels from the digital camera. For example,
a pixel with intensity I (as composed by a positive linear combination
of red, green, and blue channels) is assigned "specular"
status if (I-I.sub.o)/(I.sub.m-I.sub.o) is greater than a certain
constant b that is between 0 and 1. For example, a reasonable value
for b is 1/2. Logic may be configured to determine the optimum size
of a specular port for a particular kind of reflecting sample. Alternatively,
if the camera is sufficiently well calibrated, the color measuring
system of FIG. 4, as described directly above, may be used as a
direct reading device that may be used to separate the specular
from the matte components of reflection without recourse to multiple
measurements of the sample.
In a third mode of operation, a color measuring system of the present
invention, and specifically referring to the color measuring system
400 of FIG. 4, may be used to image a variegated sample. In this
mode of operation, the digital camera 404 is used in conjunction
with the third light source 420.sub.3 to provide calorimetric data
on small subsections of the image of a non-uniform sample. That
is, the image captured by the digital camera 404 is communicated
to a computer (not shown), such as the computing device 135 of FIGS.
1 and 2, where logic is configured to automatically segment the
image into uniformly colored areas, each of which may be separately
characterized as a respective color.
In a fourth mode of operation, a color measuring system of the
present may be used to perform shape measurement of a three-dimensional
sample. For example, a shape measurement may be performed with the
digital camera 404 by replacing one of the light sources (e.g. the
light source 110 in FIG. 1 or the second light source 420.sub.2
in FIG. 4) by a projector that projects a rectangular grid onto
a sample. The camera image of the grid conveys the three-dimensional
shape of the object, which would otherwise be inaccessible to the
camera 404. In such an embodiment of the present invention, the
projector and the digital camera 404 are configured to together
triangulate the position of a grid point, an action directly analogous
to two cameras looking at the same point in space, except the second
camera is sending instead of receiving light. The technology of
such projection, called rasterstereography, has been used in photogrammetry,
for example, and with medical-imaging applications and with industrial
inspections. Configuring a color measuring system of the present
invention as described above enables the system to perform texture
analysis on a non-smooth sample and determine physical properties
of the sample (e.g. 3-D characteristics, depth, direction of grain,
and the like).
The various modes described above may also have various interactions.
For example, for either the second or third operating modes described
above, the system may be further configured to classify the texture
of a material sample using the collected light samples and computer
algorithms. In addition, for either the second or third operating
modes, the image-segmentation logic associated with the camera may
also be used to determine the state of the opening of the sample
port, the aperture of the port, and the position of the sample (described
in greater detail below). It should be noted that a color measuring
system of the present invention may switch between its various modes
of operation by turning on and off the various included light sources.
That is, if an embodiment of a color measuring system of the present
invention includes all of the light sources necessary to perform
its various function and modes of operation, the system may vary
between its modes of operation by implementing one or more or a
combination of one or more of the included light sources.
As previously described, a color measuring system of the present
invention is able to programmatically determine an aperture size
of a sample port of a color measuring system of the present invention,
and/or determine if the sample port is open or closed. More specifically,
a color measuring system of the present invention comprising an
integrating sphere may include a digital camera operably connected
to a port of the integrating sphere. The digital camera is configured
to generate an image from light signals measured from a sample positioned
in a sample port. The color measuring system may include logic configured
to determine a size of the aperture of the sample port using the
image from the digital camera. For example, using the image of the
sample, the logic determines an area of the camera receiving color
from the sample and what areas are not by performing pixel analysis.
The area where color is located is then used to determine the size
of the aperture. In this manner, the color measuring system can
automatically determine the aperture size without using sensors,
detectors, and other mechanisms. The same technique may be used
to automatically determine if the sample port of the integrating
sphere is opened or closed.
Furthermore, a comparison of the outputs of the first and third
operating modes described above may be associated to provide a correspondence
or determine a relationship between the reflectance spectrum of
a standard patch for a colorant (the first operating mode) and a
batch application of the colorant in a non-uniform pattern (the
third operating mode). Even further, a training sample set, comprising
spatially uniform samples of known spectral reflectance, may be
used to calibrate/characterize both the integrating sphere and the
digital camera.
As described above, a set of material samples with known spectral
reflectances may be used to calibrate a color measuring system of
the present invention, and may also be used to color-characterize
the digital camera. Color characterization of the digital camera
involves determining the input colors that correspond to the output
digital values from the camera. Many different known methods and
techniques may be used to calibrate the camera. For example, a lookup
table having offset values may be generated for a set of test samples
and other values determined using interpolation techniques.
In one embodiment of the present invention, methodologies are implemented
as processor executable instructions and/or operations provided
on a computer-readable medium. Thus, in one example, a computer-readable
medium may store and/or communicate processor executable instructions
operable to perform any of the methodologies, functions, actions,
and/or their equivalents described herein. One form of computer-readable
medium may include a carrier wave that can transmit a set of processor
executable instructions over a network.
FIG. 5 depicts a high level block diagram of a computing device
suitable for use in the color measuring systems of FIGS. 1, 2 and
4 for performing the methods and operations of the present invention
in accordance with an embodiment of the present invention. The computing
device 135 of FIG. 5 illustratively comprises a processor 502, a
memory 504, and input/output ports 510 operably connected by a bus
508. The computing device 135 may be operably connected to any color
measuring system, spectrophotometer, integrating-sphere, and the
like, described herein to provide, for example, data processing
functions and storage of information. Executable components of logics
and programs described herein may be stored in and executed by the
computing device 135 of FIG. 5. It will be appreciated by those
skilled in the art and informed by the teachings of the present
invention that other computer devices may also be employed with
the various embodiments of the systems and methods of the present
invention described herein.
In one embodiment of the present invention, the computing device
135 may further include a calibration logic 730 that is configured
to perform calibration functions for a color measuring device and
camera. The calibration logic 730 may be the calibration logic 200
described in FIG. 2 and may include the same or similar components.
The computing device 135 may also include an analysis logic 735
configured to analyze image data measured from a color measuring
device/camera combination. The analysis logic 734 may be the analysis
logic 140 described in FIG. 1 and may include the same or similar
components. The calibration logic 730 and the analysis logic 735
may be embodied as processor executable instructions that can cause
the computing device 135 to perform desired functions, actions,
and/or to behave in a desired manner.
The processor 702 may be a variety of various processors including
dual microprocessor, other multi-processor architectures, an ASIC,
or other type of logic configured to process instructions. The memory
704 may include volatile memory and/or non-volatile memory. The
non-volatile memory can include, but is not limited to, read only
memory (ROM), programmable read only memory (PROM), electrically
programmable read only memory (EPROM), electrically erasable programmable
read only memory (EEPROM), and the like. Volatile memory can include,
for example, random access memory (RAM), synchronous RAM (SRAM),
dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM
(DDR SDRAM), and direct RAM bus RAM (DRRAM).
In addition, a disk 706 may be operably connected to the computing
device 135 via, for example, an input/output interface (e.g., card,
device) 718 and an input/output port 710. The disk 706 may include,
but is not limited to, devices like a magnetic disk drive, a solid
state disk drive, a floppy disk drive, a tape drive, a Zip drive,
a flash memory card, and/or a memory stick. Furthermore, the disk
706 may include optical drives like a compact disc ROM (CD-ROM),
a CD recordable drive (CD-R drive), a CD rewriteable drive (CD-RW
drive), and/or a digital video ROM drive (DVD ROM). The memory 704
is able to store executable/executing processes 714 and/or data
716, for example. The disk 706 and/or memory 704 are able to store
an operating system that controls and allocates resources of the
computing device 135.
The bus 708 of the computing device 135 of FIG. 5 may comprise
a single internal bus interconnect architecture and/or other bus
or mesh architectures. The bus 708 may be of a variety of types
including, but not limited to, a memory bus or memory controller,
a peripheral bus or external bus, a crossbar switch, and/or a local
bus. The local bus may be of varieties including, but not limited
to, an industrial standard architecture (ISA) bus, a microchannel
architecture (MSA) bus, an extended ISA (EISA) bus, a peripheral
component interconnect (PCI) bus, a universal serial (USB) bus,
and a small computer systems interface (SCSI) bus.
The computing device 135 of the present invention may interact
with input/output devices 718 via i/o interfaces and input/output
ports 710. Input/output devices 718 may include, but are not limited
to, a keyboard, a microphone, a pointing and selection device, cameras,
video cards, displays, disk 706, network devices 720, and the like.
The input/output ports 710 may include but are not limited to, serial
ports, parallel ports, and USB ports.
The computing device 135 may operate in a network environment and
thus may be connected to a color measuring device and to network
devices 720 via the i/o devices 718, a network interface card 712,
and/or the i/o ports 710. Through the network devices 720, the computing
device 135 may interact with a network. Through the network, the
computing device 135 may be logically connected to remote computers.
The networks with which the computing device 135 may interact include,
but are not limited to, a local area network (LAN), a wide area
network (WAN), and other networks. The network devices 720 may connect
to LAN technologies including, but not limited to, fiber distributed
data interface (FDDI), copper distributed data interface (CDDI),
Ethernet/IEEE 802.3, token ring/IEEE 802.5, wireless/IEEE 802.11,
Bluetooth, and the like. Similarly, the network devices 720 may
connect to WAN technologies including, but not limited to, point
to point links, circuit switching networks like integrated services
digital networks (ISDN), packet switching networks, and digital
subscriber lines (DSL). Any of these communication connections may
also be used to operably connect a color measuring device to the
computing device 135.
While the forgoing is directed to various embodiments of the present
invention, other and further embodiments of the invention may be
devised without departing from the basic scope thereof. As such,
the appropriate scope of the invention is to be determined according
to the claims, which follow. |