US 7,127,112 B2Granted

Systems for spectral multiplexing of source images to provide a composite image, for rendering the composite image, and for spectral demultiplexing of the composite image by use of an image capture device

AssigneeXerox Corporation

InventorsGaurav Sharma, Robert P. Loce, Steven J. Harrington

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Abstract

Methods and systems for spectrally-encoding plural source images and for providing the spectrally-encoded plural source images in a composite image, for rendering the composite image on a substrate, and for recovering at least one of the encoded source images from the rendered composite image. A desired source image is recovered when the rendered composite image is subjected to illumination by one or more illuminants and the desired source image is detected by one or more sensors in an image capture device. The spectral characteristics of the colorants, illuminants, and sensors are employed to spectrally encode the source image in the composite image.

Claims32

Dependent claims

A method of processing a plurality of source images, comprising the steps of:

encoding the plurality of source images to thereby provide a composite image suitable for rendering as a rendered composite image, the encoding including mapping of source image values at pixel locations in the source images to colorant control values
{
A
j
}
j
=
1
M
at respective pixel locations in a spectrally-multiplexed image plane, whereby the colorant control values specify an amount of each one of a plurality of colorants to be deposited at corresponding locations in the rendered composite image, and the rendered composite image being suited for image capture by a detector having a plurality of N sensors having respective sensitivities as a function of wavelength λ given by
{
V
1
⁡
(
λ
)
}
i
=
1
N
,
rendering the composite image on a substrate by use of a plurality of M colorants;
and
recovering a desired one of the encoded source images from the rendered composite image, such that the recovered source image is made distinguishable, by subjecting the rendered composite image to an illuminant provided from an illuminant source and to the plurality of N sensors, so as to detect the resulting recovered source image;
wherein the output spectral reflectance produced when the colorant control values are employed for each of the M colorants is given by:
r(λ;
A1, A2, . . . AM)=reflectance of region with colorant control values A1, A2, . . . AM at wavelength λ
wherein the relation between the control values used for each of the M colorants at a given pixel location and the response produced at a given pixel location by each of the N sensors is given by:
ƒi(A1, A2, . . . AM)=response of i-th capture device to a region with colorant control values A1, A2, . . . AM=∫λVi(λ)r(λ;
A1, A2, . . . AM)dλi=1,2. . . N
whereby the encoding of each source image is performed according to a determination for optimizing the effects of the following on at least one of the encoding, rendering, and recovery steps:
(a) the spectral absorption characteristics of the colorants selected for rendering the composite image:
(b) the spectral radiance characteristic of the illuminant that is used to illuminate the composite image for recovering the source image;
and (c) the spectral response characteristics of the sensors used to sense the rendered composite image during such illumination, for recovery of the desired source image.

33 more elements

An imaging system, comprising:

a spectral multiplexer for receiving image data representative of plural source images and for processing the image data to encode the source images in a composite image, and for providing a composite image data signal;
an image rendering device which is responsive to the spectral multiplexer for receiving the composite image data signal and for rendering the composite image on a substrate by use of a plurality of M colorants;
and
a demultiplexer having an illuminant source for subjecting the rendered composite image on the substrate to illumination by an illuminant having a selected spectral power distribution, and a detector including a plurality of N sensors each having a respective spectral response characteristic, whereby at least one the encoded source images is detectable by subjecting the rendered composite image to an illuminant provided from the illuminant source and to the detector, so as to detect the resulting recovered source image;
wherein the output spectral reflectance produced when the colorant control values are employed for each of the M colorants is given by:
r(λ;
A1, A2, . . . AM)=reflectance of region with colorant control values A1, A2, . . . AM at wavelength λ
wherein the relation between the control values used for each of the M colorants at a given pixel location and the response produced at a given pixel location by each of the N sensors is given by:
ƒi(A1, A2, . . . AM)=response of i-th capture device to a region with colorant control values A1, A2, . . . AM=∫λVi(λ)r(λ;
A1, A2, . . . AM)dλi1,2. . . N
whereby the encoding of at least one source image is performed according to a determination for optimizing the effects of the following on at least one of the encoding, rendering, and recovery steps:
(a) the spectral absorption characteristics of the colorants selected for rendering the composite image;
(b) the spectral radiance characteristic of the illuminant that is used to illuminate the composite image for recovering the source image;
and (c) the spectral response characteristics of the sensors used to sense the rendered composite image during such illumination, for recovery of the desired source image.

11 more elements

A method of processing a plurality of source images to provide a composite image, comprising the steps of:

receiving the plurality of source images, and
encoding the plurality of source images to thereby provide a composite image suitable for rendering as a rendered composite image, the encoding including mapping of source image values at pixel locations in the source images to colorant control values at respective pixel locations in a spectrally-multiplexed image plane, whereby the colorant control values specify an amount of each one of a plurality of colorants to be deposited at corresponding locations in the rendered composite image, and the rendered composite image being suited for image capture by a detector having a plurality of N sensors having respective sensitivities as a function of wavelength λ given by
{
V
i
⁡
(
λ
)
}
i
=
1
N
,
wherein the output spectral reflectance produced when colorant control values
{
A
j
}
j
=
1
M
are employed for each of the M colorants is given by:
r(λ;
A1, A2, AM)=reflectance of region with colorant control values A1, A2, . . . AM at wavelength λ
wherein the responses of the sensors to a region to be rendered with colorant control values {Aj}j=1M is given by:
f
i
⁡
(
A
1
,
A
2
,
…
⁢
⁢
A
M
)
=
⁢
response
⁢
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of
⁢
⁢
i
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⁢
th
⁢
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capture
⁢
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device
⁢
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to
⁢
⁢
a
⁢
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region
⁢
⁢
with
⁢
colorant
⁢
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control
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values
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A
1
,
A
2
,
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A
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=
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∫
λ
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λ
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⁢
r
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(
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A
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)
⁢
ⅆ
λ
⁢
⁢
i
=
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…
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N
which characterizes the relation between the colorant control values employed for each of the M colorants at a given pixel location and the response produced at the given pixel location by each of the N sensors;
whereby the mapping of the pixel values from the plurality of source images is determined according to:
(a) a plurality of spatial luminance distributions each of which represent the desired response of the rendered composite image to illumination Thereof by a respective one of a plurality of narrow band illuminants, and (b) the spectral response characteristics of the N sensors.

141 more elements

A computer program embodied on a computer readable medium, the program being executable for processing a plurality of source images to provide a composite image, comprising the steps of:

receiving the plurality of source images, and
encoding the plurality of source images to thereby provide a composite image suitable for rendering as a rendered composite image, the encoding including mapping of source image values at pixel locations in the source images to colorant control values at respective pixel locations in a spectrally-multiplexed image plane, whereby the colorant control values specify an amount of each one of a plurality of colorants to be deposited at corresponding locations in the rendered composite image, and the rendered composite image being suited for image capture by a detector having a plurality of N sensors having respective sensitivities as a function of wavelength λ given by {Vi(λ)}i=1N;
wherein the output spectral reflectance produced when colorant control values {Aj}j=1M are employed for each of the M colorants is given by:
r(λ;
A1, A2, . . . AM)=reflectance of region with colorant control values A1, A2, . . . AM at wavelength λ
wherein the responses of the sensors to a region to be rendered with colorant control values {Aj}j=1M is given by:
ƒi(A1, A2, . . . AM)=response of i-th capture device to a region with colorant control values A1, A2, . . . AM=∫λV(λ)r(λ;
A1, A2, . . . AM)dλi=1,2. . . N
which characterizes the relation between the colorant control values employed for each of the M colorants at a given pixel location and the response produced at the given pixel location by each of the N sensors;
whereby the mapping of the pixel values from the plurality of source images is determined according to:
(a) a plurality of spatial luminance distributions each of which represent the desired response of the rendered composite image to illumination thereof by a respective one of a plurality of narrow band illuminants, and (b) the spectral response characteristics of the N sensors.

8 more elements

Dependencies are inferred from the claim text.