U.S. patent application number 09/944341 was filed with the patent office on 2002-04-04 for color character description apparatus, color management apparatus, image conversion apparatus and color correction method.
This patent application is currently assigned to Mitsubishi Denki Kabushiki Kaisha. Invention is credited to Kagawa, Shuichi, Matoba, Narihiro, Saito, Masayuki, Sato, Tsuneo, Sugiura, Hiroaki, Takahashi, Mariko.
Application Number | 20020039104 09/944341 |
Document ID | / |
Family ID | 17702171 |
Filed Date | 2002-04-04 |
United States Patent
Application |
20020039104 |
Kind Code |
A1 |
Sato, Tsuneo ; et
al. |
April 4, 2002 |
Color character description apparatus, color management apparatus,
image conversion apparatus and color correction method
Abstract
A process is provided for developing and converting a lookup
table (hereinafter called a "LUT") composed of only characteristic
points of the characteristic of a color device and having a volume
smaller than that of a multidimensional LUT into a multidimensional
LUT by a table development process. Image data converting means
uses the multidimensional LUT to convert input image data into
output image data. Thus, an effect can be obtained in that a color
management apparatus can be operated with only the LUT composed of
only characteristic points of the characteristic of the device and
having a small volume.
Inventors: |
Sato, Tsuneo; (Tokyo,
JP) ; Takahashi, Mariko; (Tokyo, JP) ; Matoba,
Narihiro; (Tokyo, JP) ; Sugiura, Hiroaki;
(Tokyo, JP) ; Kagawa, Shuichi; (Tokyo, JP)
; Saito, Masayuki; (Tokyo, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
Mitsubishi Denki Kabushiki
Kaisha
|
Family ID: |
17702171 |
Appl. No.: |
09/944341 |
Filed: |
September 4, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09944341 |
Sep 4, 2001 |
|
|
|
09256368 |
Feb 24, 1999 |
|
|
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Current U.S.
Class: |
345/600 |
Current CPC
Class: |
H04N 1/60 20130101; G09G
5/06 20130101; H04N 1/6019 20130101 |
Class at
Publication: |
345/600 |
International
Class: |
G09G 005/02 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 8, 1998 |
JP |
10- 286268 |
Claims
What is claimed is:
1. A color characteristic description apparatus for producing color
characteristic data for use when supplied image data is converted
into output image data, comprising: a lookup table of color
characteristic data, wherein said lookup table is composed of only
characteristic points which indicate the relationship between
supplied image signals and output image signals which are
determined to be impossible to be developed in a table development
process which is performed when said lookup table is developed into
a multidimensional lookup table.
2. A color characteristic description apparatus according to claim
1, wherein said lookup table composed of the characteristic points
is described such that fundamental colors composed of primary
colors of a color device having the same signal values serve as the
characteristic points.
3. A color characteristic description apparatus according to claim
1, wherein color characteristic data which is produced by said
color characteristic description apparatus contains, in addition to
said lookup table, an identifier for identifying a table
development method which is employed when said lookup table is
developed into the multidimensional lookup table.
4. A color characteristic description apparatus according to claim
1, wherein color characteristic data which is produced by said
color characteristic description apparatus contains, in addition to
said lookup table, software for performing a table development
process.
5. A color characteristic description apparatus according to claim
4, wherein color characteristic data which is produced by said
color characteristic description apparatus further contains an
identifier for identifying a table development method and software
for converting data developed into the table into an ICC
profile.
6. A color characteristic description apparatus for producing color
characteristic data for use when supplied image data is converted
into output image data, comprising: a multidimensional lookup table
which is produced by said color characteristic description
apparatus; wherein color characteristic data which is produced by
said color characteristic description apparatus incorporates data
obtained by compressing said multidimensional lookup table and an
identifier for identifying a restoring method for restoring the
compressed multidimensional lookup table.
7. A color characteristic description apparatus for producing color
characteristic data for use when supplied image data is converted
into output image data, comprising: a multidimensional lookup table
which is produced by said color characteristic description
apparatus, wherein color characteristic data which is produced by
said color characteristic description apparatus incorporates data
obtained by compressing said multidimensional lookup table and
software for restoring compressed data.
8. A color characteristic description apparatus according to claim
7, wherein color characteristic data which is produced by said
color characteristic description apparatus further incorporates an
identifier for identifying a restoring method for restoring
compressed data and software for converting the restored
multidimensional lookup table into an ICC profile.
9. A color management apparatus for converting supplied image data
by using a lookup table of color characteristic data into output
image data, said color management apparatus comprising: a lookup
table which is composed of characteristic points which are points
indicating the relationship between supplied image data and output
image data which are determined to be impossible to be interpolated
when a process for converting image data is performed; and image
data converting means for converting supplied image data by using
said lookup table composed of the characteristic points into output
image data.
10. A color management apparatus according to claim 9, further
comprising table development means for developing said lookup table
into the multidimensional lookup table; wherein said image data
converting means uses the multidimensional lookup table developed
by said table development means to convert supplied image data into
output image data.
11. A color management apparatus according to claim 10, wherein
said table development means develops said lookup table into said
multidimensional lookup table in such a manner that all of
characteristic points of said lookup table composed of the
characteristic points are contained.
12. A color management apparatus according to claim 10, wherein
said table development means develops said lookup table into the
multidimensional lookup table such that data corresponding to grid
points of said multidimensional lookup table is composed of output
data of said lookup table and data of information of adjacent grid
points for interpolating a portion between grid points.
13. A color management apparatus according to claim 10, wherein
said multidimensional lookup table is a compressed multidimensional
lookup table formed by compressing said multidimensional lookup
table; restoring means is provided which restores said compressed
multidimensional lookup table into said multidimensional lookup
table; said image data converting means causes said restoring means
to restore said compressed multidimensional lookup table and uses
obtained multidimensional lookup table to convert supplied image
data into output image data.
14. color management apparatus according to an claim 9, further
comprising: table recording means for recording said
multidimensional lookup table developed by said table development
means in a memory; and updating means for operating said table
development means and said table recording means when said lookup
table composed of the characteristic points has been updated to
update said multidimensional lookup table and rewrite the updated
multidimensional lookup table on said memory, wherein said image
data converting means uses said multidimensional lookup table
recorded in said memory to convert supplied image data into output
image data.
15. An image converting apparatus comprising: a color management
apparatus incorporating image data converging means which uses a
lookup table of color characteristic data produced by a
characteristic description apparatus to convert supplied image data
into output image data and which has a structure that said lookup
table is composed of characteristic points which are points
indicating the relationship between supplied image data and output
image data which are determined to be impossible to be interpolated
when said image data converting means performs an image data
converting process; and a storage portion for storing a plurality
of color characteristic data items having different color
characteristics; wherein color characteristic data is selected in
accordance with the characteristic of image data and selected color
characteristic data is used by said color management apparatus to
convert supplied image data into output image data.
16. A color correction method structured such that a
multidimensional lookup table is used to convert a supplied image
signal into an output image signal, said color correction method
comprising the steps of: producing a lookup table composed of
characteristic points which are points indicating the relationship
between input color image signals and output color image signals
which are determined to be impossible to be developed in a table
development process; performing table development process such that
said lookup table composed of the characteristic points is
developed into a multidimensional lookup table; and converting
supplied image signal into an output image signal by using said
multidimensional lookup table obtained by developing said lookup
table composed of the characteristic points.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a color characteristic
description apparatus for use in a system for handling images, a
color management apparatus and an image converting apparatus to
which the color characteristic description apparatus is applied and
a color correction method.
[0003] 2. Description of the Related Art
[0004] FIG. 29 shows one of tag types which are elements of a
profile for describing a color characteristic disclosed in, for
example, "ICC Profile Format Specification, Version 3.3, Nov. 11,
1996, International Color Consortium". Referring to FIG. 31, bytes
0 to 3 are identifiers, 4 to 7 are reserved bytes, 8 is the number
of input channels, 9 is the number of output channels, 10 is the
number of grid points in multidimensional lookup table to be
described later, 11 is a reserved byte for padding, 12 to 15, 16 to
19, 20 to 23, 24 to 27, 28 to 31, 32 to 35, 36 to 39, 40 to 43 and
44 to 47 are encoded parameters eij (i, j=0 to 2), 48 to m are
input one-dimensional tables, m+1 to n are n-dimensional m bytes (n
is the number of input channels and m is the number of output
channels). The above-mentioned table is also called a
multidimensional lookup table. Note that n+1 to o is an output
one-dimensional lookup table.
[0005] A process for converting a supplied image signal into an
output image signal by using data shown in FIG. 29 is shown in FIG.
30. Referring to the drawing, C1 shows a conventional process for
converting an image signal. A supplied image signal is first
subjected to a process C11 using a matrix. The matrix is described
with parameter eij (i, j=0 to 2) of tag types 12 to 15, 16 to 19,
20 to 23, 24 to 27, 28 to 31, 32 to 35, 36 to 39, 40 to 43 and 44
to 47. The calculation is performed in accordance with Equation 1
on an assumption that a supplied image signal is [X, Y, Z]: 1 [ X '
Y ' Z ' ] = [ e00 e01 e02 e10 e11 e12 e20 e21 e22 ] [ X Y Z ] ( 1
)
[0006] In the foregoing formula, [X', Y', Z'] is a value of the
signal converted into the matrix. Note that the process using the
matrix is performed only when the color space of the supplied image
signal is XYZ color space.
[0007] Then, a process C12 using an input one-dimensional lookup
table is performed. The input one-dimensional lookup table is
composed of data written in 48 byte to m byte of a tag type.
One-byte data corresponding to input signal 0 to 255, that is,
256-byte data is used as data for one channel. The input
one-dimensional lookup table is composed of input channel data
(256.times.input channels). Assuming that an input signal is [A0,
B0, C0], a calculation is performed in accordance with Equation
2.
A1=f.sub.1(A0)
B1=g.sub.1(B0)
C1=h.sub.1(C0) (2)
[0008] In the foregoing equation, [A1, B1, C1] is a value of the
signal subjected to the process using the input one-dimensional
lookup table. Moreover, f1, g1 and h1 are functions indicated by
the input one-dimensional lookup table for each channel.
[0009] Then, a process C13 using a multidimensional lookup table is
performed. The multidimensional lookup table is composed of data
written in m+1 to n bytes of the tag type. In an example case of a
three-dimensional input and three-dimensional output
multidimensional lookup table, a value [A2, B2, C2] (three bytes)
of a signal obtained by subjecting an input signal [A1, B1, C1]
(three byte) to the process using the multidimensional lookup table
is composed of data for the number of input signals corresponding
to grid points of the multidimensional lookup table. The byte size
of the multidimensional lookup table is expressed by the following
Equation 3.
TableSize=GridPoints.sup.Inputchannels.multidot.OutputChannels
(3)
[0010] In the foregoing equation, "Tablesize" is the size of the
multidimensional lookup table, "GridPoints" is the number of grid
points of the multidimensional lookup table, "InputChannels" is the
number of input channels and "OutputChannels" is the number of
output channels.
[0011] The process using the multidimensional lookup table is
performed as follows. Assuming that the input signal is [A1, B1,
C1], a value of the processed signal is [A2, b2, C2] and the
process using the multidimensional lookup table is expressed by F,
a calculation is performed in accordance with Equation 4. The
foregoing process is characterized in that combined data [A1, B1,
C1] of the input signals for three channels is performed.
[A2, B2, C2]=F([A1 B1 C1]) (4)
[0012] Then, a process C14 using an output one-dimensional lookup
table is performed. The input one-dimensional lookup table is
composed of data written on n+1 byte to o byte of the tag type.
Similarly to the input one-dimensional lookup table, the output
one-dimensional lookup table is composed of one-byte data
corresponding to 0 to 255 of the input signal, that is, the input
one-dimensional lookup table is composed of data of input channels
(256.times.input channels) on an assumption that 256-byte data is
data for one channel. Assuming that an input signal is [A2, B2,
C2], a calculation is performed in accordance with Equation 5.
A3=f.sub.2(A2)
B3=g.sub.2(B2)
C3=h.sub.2(C2) (5)
[0013] In the foregoing equation, [A3, B3, C3] is a value of the
signal subjected to the process using the output one-dimensional
lookup table and f2, g2 and h2 are functions indicated by the
output one-dimensional lookup table for each channel.
[0014] The conventional tag type which is an element of a profile
for describing the color characteristic disclosed in "ICC Profile
Format Specification, Version 3.3, Nov. 11, 1996, international
Color Consortium" has been described as described above. Moreover,
the signals have been processed as described above in accordance
with described data. Therefore, the profile of a color device
having a complicated color characteristic has a problem in that the
size of the multidimensional lookup table is enlarged excessively.
For example, the size of a three-dimensional input and
four-dimensional output multidimensional lookup table having 65
grid points is 1,098,500 bytes, which is about one megabyte which
is calculated in accordance with above-mentioned Equation (3). What
is worse, the multidimensional lookup table of the above-mentioned
type cannot satisfactorily describe the color characteristic of the
actual color device. If the table having the above-mentioned size
is added to image data which is handled by the color device, the
quantity of data corresponding to the above-mentioned volume is
enlarged. In the foregoing case, communication cost is enlarged
excessively when image data is communicated through a communication
line or the like.
SUMMARY OF THE INVENTION
[0015] To overcome the above-mentioned problem, an object of the
present invention is to provide a method of obtaining precise color
characteristic data without enlargement of the quantity of color
characteristic data, a color characteristic description method and
an apparatus to which the methods are applied.
[0016] A color characteristic description apparatus according to a
first aspect of the present invention for producing color
characteristic data for use when supplied image data is converted
into output image data, comprises: a lookup table of color
characteristic data, wherein the lookup table is composed of only
characteristic points which indicate the relationship between
supplied image signals and output image signals which are
determined to be impossible to be developed in a table development
process which is performed when the lookup table is developed into
a multidimensional lookup table.
[0017] A color characteristic description apparatus according to
the second aspect of the present invention has a structure that the
lookup table composed of the characteristic points is described
such that fundamental colors composed of primary colors of a color
device having the same signal values serve as the characteristic
points.
[0018] A color characteristic description apparatus according to a
third aspect of the present invention has a structure that color
characteristic data which is produced by the color characteristic
description apparatus contains, in addition to the lookup table, an
identifier for identifying a table development method which is
employed when the lookup table is developed into the
multidimensional lookup table.
[0019] A color characteristic description apparatus according to a
fourth aspect of the present invention has a structure that color
characteristic data which is produced by the color characteristic
description apparatus contains, in addition to the lookup table,
software for performing a table development process.
[0020] A color characteristic description apparatus according to a
fifth aspect of the present invention has a structure that color
characteristic data which is produced by the color characteristic
description apparatus further contains identifiers for identifying
a table development method and software for converting data
developed into the table into an ICC profile.
[0021] A color characteristic description apparatus according to a
sixth aspect of the present invention for producing color
characteristic data for use when supplied image data is converted
into output image data, comprises: a multidimensional lookup table
which is produced by the color characteristic description
apparatus, wherein color characteristic data which is produced by
the color characteristic description apparatus incorporates data
obtained by compressing the multidimensional lookup table and an
identifier for identifying a restoring method for restoring the
compressed multidimensional lookup table.
[0022] A color characteristic description apparatus according to a
seventh aspect of the present invention for producing color
characteristic data for use when supplied image data is converted
into output image data, comprises: a multidimensional lookup table
which is produced by the color characteristic description
apparatus, wherein color characteristic data which is produced by
the color characteristic description apparatus incorporates data
obtained by compressing the multidimensional lookup table and
software for restoring compressed data.
[0023] A color management apparatus according to an eighth aspect
of the present invention has a structure that color characteristic
data which is produced by the color characteristic description
apparatus further incorporates an identifier for identifying a
restoring method for restoring compressed data and software for
converting the restored multidimensional lookup table into an ICC
profile.
[0024] A color management apparatus according to a ninth aspect of
the present invention for converting supplied image data by using a
lookup table of color characteristic data into output image data,
the color management apparatus comprises: a lookup table which is
composed of characteristic points which are points indicating the
relationship between supplied image data and output image data
which are determined to be impossible to be interpolated when a
process for converting image data is performed; and image data
converting means for converting supplied image data by using the
lookup table composed of the characteristic points into output
image data.
[0025] A color management apparatus according to a tenth aspect of
the present invention further comprises table development means for
developing the lookup table into the multidimensional lookup table,
wherein the image data converting means uses the multidimensional
lookup table developed by the table development means to convert
supplied image data into output image data.
[0026] A color management apparatus according to an eleventh aspect
of the present invention has a structure that the table development
means develops the lookup table into the multidimensional lookup
table in such a manner that all of characteristic points of the
lookup table composed of the characteristic points are
contained.
[0027] A color management apparatus according to a twelfth aspect
of the present invention has a structure that the table development
means develops the lookup table into the multidimensional lookup
table such that data corresponding to grid points of the
multidimensional lookup table is composed of output data of the
lookup table and data of information of adjacent grid points for
interpolating a portion between grid points.
[0028] A color management apparatus according to a thirteenth
aspect of the present invention has a structure that the
multidimensional lookup table is a compressed multidimensional
lookup table formed by compressing the multidimensional lookup
table, restoring means is provided which restores the compressed
multidimensional lookup table into the multidimensional lookup
table, and the image data converting means causes the restoring
means to restore the compressed multidimensional lookup table and
uses obtained multidimensional lookup table to convert supplied
image data into output image data.
[0029] A color management apparatus according to a fourteenth
aspect of the present invention further comprises: table recording
means for recording the multidimensional lookup table developed by
the table development means in a memory; and updating means for
operating the table development means and the table recording means
when the lookup table composed of the characteristic points has
been updated to update the multidimensional lookup table and
rewrite the updated multidimensional lookup table on the memory,
wherein the image data converting means uses the multidimensional
lookup table recorded in the memory to convert supplied image data
into output image data.
[0030] A color management apparatus according to a fifteenth aspect
of the present invention comprises: image data converging means
which uses a lookup table of color characteristic data produced by
a characteristic description apparatus to convert supplied image
data into output image data and which has a structure that the
lookup table is composed of characteristic points which are points
indicating the relationship between supplied image data and output
image data which are determined to be impossible to be interpolated
when the image data converting means performed an image data
converting process; and a storage portion for storing a plurality
of color characteristic data items having different color
characteristics, wherein color characteristic data is selected in
accordance with the characteristic of image data and selected color
characteristic data is used by the color management apparatus to
convert supplied image data into output image data.
[0031] A color correction method according to a sixteenth aspect of
the present invention and structured such that a multidimensional
lookup table is used to convert a supplied image signal into an
output image signal, the color correction method comprising the
steps of: producing a lookup table composed of characteristic
points which are points indicating the relationship between input
color image signals and output color image signals which are
determined to be impossible to be developed in a table development
process; performing table development process such that the lookup
table composed of the characteristic points is developed into a
multidimensional lookup table; and converting supplied image signal
into an output image signal by using the multidimensional lookup
table obtained by developing the lookup table composed of the
characteristic points.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 is a block diagram showing the overall structure
according to a first embodiment of the present invention.
[0033] FIG. 2 is a diagram showing a lookup table according to the
first embodiment of the present invention.
[0034] FIG. 3 is a diagram showing grid points of the lookup table
according to the first embodiment of the present invention.
[0035] FIGS. 4A to 4F are diagrams showing a lookup table composed
of only characteristic points according to the first embodiment of
the present invention.
[0036] FIGS. 5A and 5B are diagrams showing a table development
process according to the first embodiment of the present
invention.
[0037] FIG. 6 is a diagram showing the structure of color
characteristic data according to the first embodiment of the
present invention.
[0038] FIG. 7 is a diagram showing the structure of an image data
format according to the first embodiment of the present
invention.
[0039] FIG. 8 is a diagram showing the structure of color
characteristic data according to a second embodiment of the present
invention.
[0040] FIG. 9 is a diagram showing the structure of color
characteristic data according to a third embodiment of the present
invention.
[0041] FIG. 10 is a block diagram showing a color management
apparatus according to a fourth embodiment of the present
invention.
[0042] FIG. 11 is a diagram showing image data conversion process
according to the fourth embodiment of the present invention.
[0043] FIG. 12 is a block diagram showing a color management
apparatus according to a fifth embodiment of the present
invention.
[0044] FIG. 13 is a diagram showing grid points of a lookup table
according to a fifth embodiment of the present invention.
[0045] FIG. 14 is a diagram showing an image data converting
process according to the fifth embodiment of the present
invention.
[0046] FIGS. 15A and 15B are diagrams showing the structure of a
multidimensional LUT data format according to the fifth embodiment
of the present invention.
[0047] FIG. 16 is a block diagram showing the overall body
according to a sixth embodiment of the present invention.
[0048] FIG. 17 is a diagram showing the structure of color
characteristic data according to the sixth embodiment.
[0049] FIG. 18 is a diagram showing the structure of color
characteristic data according to a seventh embodiment of the
present invention.
[0050] FIG. 19 is a diagram showing the structure of color
characteristic data according to an eighth embodiment of the
present invention.
[0051] FIG. 20 is a block diagram showing a color management
apparatus according to a ninth embodiment of the present
invention.
[0052] FIG. 21 is a graph showing the color characteristic of a
color device according to a tenth embodiment of the present
invention.
[0053] FIGS. 22A to 22C are diagrams showing fundamental colors
according to the tenth embodiment of the present invention.
[0054] FIG. 23 is a block diagram showing a color management
apparatus according to an eleventh embodiment of the present
invention.
[0055] FIG. 24 is a diagram showing the structure of color
characteristic data according to the eleventh embodiment of the
present invention.
[0056] FIG. 25 is a block diagram showing a color management
apparatus according to a twelfth embodiment of the present
invention.
[0057] FIG. 26 is a diagram showing the structure of color
characteristic data according to the twelfth embodiment of the
present invention.
[0058] FIG. 27 is a flow chart of data in an image converting
apparatus according to a thirteenth embodiment of the present
invention.
[0059] FIG. 28 is a flow chart of data in an image converting
apparatus according to a fourteenth embodiment of the present
invention.
[0060] FIG. 29 is a diagram showing a tag type of a conventional
apparatus.
[0061] FIG. 30 is a diagram showing a process for converting image
data in the conventional apparatus.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0062] Now, a description will be given in more detail of preferred
embodiments of invention with reference to the accompanying
drawings.
[0063] (First Embodiment)
[0064] A first embodiment of the present invention will now be
described. FIG. 1 is a block diagram showing the overall structure
of a first embodiment of the present invention. Reference numeral 1
represents a digital camera which is an image input apparatus (a
color device). Reference numeral 2 represents a color
characteristic description apparatus for producing color
characteristic data structured as shown in FIG. 6 and incorporating
a lookup table (hereinafter called a "LUT") composed of
characteristic points adapted to the color characteristic of the
digital camera which has been measured by a calorimeter and an
identifier indicating a table development method. Reference numeral
3 represents a data processing means for converting an image
photographed by the digital camera into digital image data signal.
Reference numeral 4 represents a synthesizer for synthesizing color
characteristic data and the image data signal into an image data
format. The color characteristic of the digital camera may be
examined in a real time manner when the data processing means 3
converts the photographed image into the digital image data
signal.
[0065] Reference numeral 10 represents a color printer for printing
the image photographed by the digital camera 1. Reference numeral
11 represents a separator for separating the image data format
transmitted from the digital camera 1 into an image data signal and
color characteristic data. Reference numeral 12 represents a LUT of
color characteristic data. Reference numeral 13 represents a table
development means. Reference numeral 14 represents a
multidimensional LUT developed by the table development means.
Reference numeral 15 represents an image-data converting means
using the multidimensional LUT 14 to convert input image data
separated by the separator 11 into output image data. The separator
11, the table development means 13, the multidimensional LUT 14 and
the image-data converting means 15 constitute a color management
apparatus 16.
[0066] A signal transmitted from the color management apparatus 16
is processed in the color printer 10 similarly to the conventional
structure so that the signal is printed.
[0067] The operation will now be described. The LUT is a table
showing the relationship between certain input signals (I0, I1, . .
. , In) and output signals (00, 01, . . . , Om) which must be
transmitted, as shown in FIG. 2, where n and m are each an integer.
As a matter of course, the foregoing LUT is a LUT only for
describing the color characteristic of the color device.
[0068] FIG. 2 shows a table for converting n-dimensional input into
m-dimensional output. Although the relationship between all of the
inputs and outputs may be described in the foregoing LUT,
enlargement of the number-of combinations of the inputs and outputs
must be prevented. In general, a LUT composed of a combination of
inputs and outputs at grid points constituted by equally dividing
the input side axis is employed in general.
[0069] A LUT of the foregoing type composed of the pairs of an
input and an output at each of the grid points formed by equally
dividing the input side axis is generally called a multidimensional
LUT 14.
[0070] FIG. 3 shows an example of the multidimensional LUT 14 in a
case of one dimension. If nine input points exists, grid points
having intervals of 2 are shown in example 1. Grid points having
intervals of 4 are shown in example 2. The other dimensions are
similar to the example of the one dimension.
[0071] The number of pairs of inputs and outputs can be reduced as
compared with the number of pairs of all of inputs and outputs.
However, the multidimensional LUT 14 must incorporate a LUT
composed of a large number of pairs of inputs and outputs to
improve the accuracy when the color characteristic of a color
device is described. Therefore, the present invention incorporates
the LUT 12 composed of the characteristic points. The LUT 12
composed of the characteristic points will now be described with
reference to FIGS. 4A tp 4F.
[0072] FIGS. 4A to 4F are graphs showing the relationship between
one-dimensional inputs and outputs. In a case of the relationship
between inputs and outputs shown in FIG. 4A, the relationship
between inputs and outputs shown in FIG. 4A can be obtained if the
relationship between inputs and outputs of a first point and a
final point because a straight line can be determined when two
points are given. A point indicating the relationship between the
first point and the final point is called a characteristic point in
the present invention. The characteristic points of the
relationship between the input and output shown in FIG. 4A are
expressed with a double line circles in FIG. 4B. In a case of the
relationship between the inputs and outputs in the form of a broken
line shown in FIG. 4C, the characteristic points are points
indicating the relationship between the first point and the final
point and that between the input and output at each broken point as
shown in FIG. 4D. In a further complicated relationship between
inputs and outputs as shown in FIG. 4E, the characteristic points
are the first and final points and points at each of which the
curvature of the relationship between the inputs and outputs is
considerably changed. FIG. 4F shows characteristic points in FIG.
4E. The characteristic point are changed depending on the process
which is performed by the table development means 13 which will be
described below. In the present invention, points indicating the
relationship between inputs and outputs which are determined to be
impossible to be developed in a table development process are
defined to be the characteristic points.
[0073] The data processing means 3 converts the image photographed
by the digital camera 1 into a digital signal. The digital image
signal and color characteristic data having the lookup table
composed of only the characteristic points adapted to the color
characteristic of the digital camera and an identifier indicating a
table development method are synthesized by the synthesizer 4 into
an image data format which is then transmitted to the color printer
10. The structure of color characteristic data is shown in FIG. 6.
Referring to FIG. 6, reference numeral 17 represents color
characteristic data, 12 represents the LUT composed of only the
characteristic points and 18 represents the identifier indicating a
table development method.
[0074] The structure of the image data format synthesized by the
synthesizer 4 is shown in FIG. 7. Reference numeral 19 represents
an image data format, 17 represents color characteristic data and
20 represents image data.
[0075] In the color printer 10, the separator 11 performs
separation into color characteristic data 17 and image data 20.
Color characteristic data 17 is supplied to the table development
means 13, while image data 20 is supplied to the image-data
converting means 15.
[0076] The operation of the table development means 13 will now be
described. The table development means 13 develops the LUT 12
composed of only the characteristic points into the
multidimensional LUT 14 by selecting a table development method
suitable to the color characteristic of the digital camera 1 by the
identifier 18 of color characteristic data 17. As described above,
the multidimensional LUT 14 is a LUT composed of pairs of inputs
and outputs at the grid points formed by equally dividing the input
side axis. On the other hand, the LUT 12 composed of only the
characteristic points is a LUT composed of the pairs of the
relationship of the inputs and outputs which are determined to be
impossible to be developed in the development process which is
performed by the table development means 13. Therefore, the
characteristic points are not always positioned on the grid points
formed by equally dividing the input side axis. Therefore, the grid
points formed by equally dividing the input side axis are made to
be the inputs. Moreover, the LUT 12 composed of only the
characteristic points is used to perform an operation for obtaining
outputs so as to obtain the multidimensional LUT 14.
[0077] The process shown in FIGS. 5A and 5B will now be described
such that the LUT 12 composed of the characteristic point of
one-dimensional inputs and one-dimensional outputs is taken as an
example. FIGS. 5A and 5B show a structure in which the relationship
between inputs and outputs of grid points formed by dividing the
input side axis into six portions is obtained. To obtain the
relationship between the inputs and outputs of the grid points
except for the characteristic points, interpolation is performed by
using the adjacent characteristic points. The interpolation may be
a known straight interpolation or spline interpolation. FIG. 5A
shows a table development process employing the straight
interpolation. Start points of arrows in the form of dashed lines
indicating the correspondence between inputs and outputs of each
grid point of the multidimensional LUT 14 are input values. Final
points of the arrows are output values corresponding to the input
values. FIG. 5B shows a table development process employing the
spline interpolation. Start points of arrows in the form of dashed
lines indicating the correspondence between inputs and outputs at
the grid points of the multidimensional LUT 14 are input value.
Final points of the arrows are output values corresponding to the
input values. Thus, the multidimensional LUT 14 is produced by the
process performed by the table development means 13. FIGS. 5A and
5B show the LUT 12 composed of the characteristic points of
one-dimensional inputs and one-dimensional outputs. However, also a
LUT 12 composed of characteristic points of n-dimensional inputs
and m-dimensional outputs enables the multidimensional LUT 14 to be
obtained after a similar process has been performed. In this case,
a complicated interpolation process must be performed as compared
with the straight interpolation and the spline interpolation which
are simple interpolations.
[0078] Then, the image-data converting means 15 will now be
described which performs the interpolation similarly to the table
development means 13 except for the multidimensional LUT 14 which
is used by the image-data converting means 15. Since the
multidimensional LUT 14 is composed of the grid points obtained by
equally dividing the input side axis, retrieval of the table can
easily be performed as compared with a process using the LUT 12.
Moreover, the calculations for the interpolation can independently
be performed for each axis. Therefore, data in a large quantity,
such as image data 20, can quickly be converted.
[0079] Input image data of the image-data converting means 15
varies depending upon the type of the image input apparatus. Input
image data is digital image signals, such as R, G and B signals of
a scanner, R, G and B signals of a monitor, R, G and B signals of a
CIE, X, Y and Z signals of the CIE or L, a and b signals of the
CIE. On the other hand, output data of the image-data converting
means 15 depends on the contents of the table development means 13,
that is, the type of the image input apparatus. Output data above
is R, G and B signals of a scanner, R, G and B signals of a
monitor, C, M and Y signals of a printer, R, G and B signals of a
CIE, X, Y and Z signals of the CIE or L, a and b signals of the
CIE.
[0080] As described above, the first embodiment has the process for
converting the LUT 12 having a smaller quantity as compared with
the multidimensional LUT 14 and composed of only the characteristic
points of the characteristic of the digital camera 1 into the
multidimensional LUT 14 by the table development means 13.
Therefore, the characteristic of the image input apparatus can be
described by only the LUT 12 having a small quantity and composed
only the characteristic points.
[0081] (Second Embodiment)
[0082] A second embodiment of the present invention will now be
described. FIG. 8 is a diagram showing the structure of color
characteristic data 17 according to the second embodiment of the
present invention. Color characteristic data 17 is another example
of color characteristic data 17 which is produced by the color
characteristic description apparatus 2 shown in FIG. 1. Reference
numeral 17 represents color characteristic data according to the
present invention. Reference numeral 12 represents a LUT which is
an element of color characteristic data 17 and composed of
characteristic points. Reference numeral 21 represents software
which is an element of color characteristic data 17 and which
performs a table development process.
[0083] The operation of a color management apparatus using color
characteristic data 17 according to the second embodiment will now
be described such that the first embodiment is taken as an example.
The LUT 12 composed of only the characteristic points in color
characteristic data 17 is employed as the LUT 12 composed of only
characteristic points in the color management apparatus 16
according to the first embodiment. Software 21 in the color
characteristic data 17 for performing a table development process
is loaded as software of the table development means 13 and
executed so that the table development is performed. Thus,
development to the multidimensional LUT 14 is performed. Then, the
image-data converting means 15 uses the multidimensional LUT 14 to
convert input image data into output image data.
[0084] As described above, the second embodiment has the structure
that color characteristic data 17 is composed of the LUT 12
composed of only characteristic points and the software 21 for
performing the table development process. Therefore, the color
management apparatus 16 incorporating the LUT 12 composed of only
the characteristic points according to the first embodiment can be
operated such that the table development means 13 changes the
development method to correspond to color characteristic data
17.
[0085] (Third Embodiment)
[0086] A third embodiment of the present invention will now be
described with reference to the drawings. FIG. 9 is a diagram
showing color characteristic data according to the third embodiment
of the present invention. Color characteristic data according to
this embodiment is another example of color characteristic data 17
which is produced by the color characteristic description apparatus
2 shown in FIG. 1. Reference numeral 17 represents color
characteristic data according to the present invention. Reference
numeral 12 represents a LUT which is an element of color
characteristic data 17 and which is composed of only characteristic
points. Reference numeral 18 represents an identifier which is an
element of color characteristic data 17 and which indicates a table
development method. Reference numeral 22 represents software which
is an element of color characteristic data 17 and which performs
the table development process.
[0087] The operation of a color management apparatus using color
characteristic data 17 according to the third embodiment will now
be described. The LUT 12 which is included in color characteristic
data 17 and which is composed of only characteristic points is used
as the LUT 12 in the color management apparatus 16 according to the
first embodiment, the LUT 12 being composed of only characteristic
points. The identifier 18 indicating the table development method
is used by a CPU (not shown) or the like which selects the
development method to which the table development means 12
corresponds. If any corresponding table development method does not
exist, software 22 in color characteristic data 17 for performing
the table development process is loaded as software for the table
development means 13. Then, the table development means 13 performs
table development so that development into the multidimensional LUT
14 is performed. Then, the Image-data converting means 15 uses the
multidimensional LUT 14 to convert input image data into output
image data.
[0088] As described above, the third embodiment has the structure
that color characteristic data 17 is composed of the LUT 12 which
is composed of only characteristic points, the identifier 18
indicating the table development method and the software 22 for
performing the table development. Therefore, the digital camera 1
according to the first embodiment and arranged to use the LUT 12
which is composed of only characteristic points is able to perform
table development if an appropriate table development method
exists. Even if any appropriate table development method does not
exist, the software 22 for performing the table development is
loaded to perform the table development. Thus, the digital camera 1
can be operated as described above.
[0089] (Fourth Embodiment)
[0090] A fourth embodiment of the present invention will now be
described. FIG. 10 is a block diagram showing a color management
apparatus 16 according to a fourth embodiment of the present
invention. Reference numeral 16 represents a color management
apparatus according to the present invention. Reference numeral 12
represents a LUT composed of only characteristic points. Reference
numeral 23 represents an image-data converting means for converting
input image data into output image data by using the LUT 12
composed of only characteristic points. Input image data of the
image-data converting means varies depending on the type of the
image input apparatus. Input image data is digital image signals,
such as R, G and B signals of a scanner, R, G and B signals of a
monitor, R, G and B signals of a CIE, X, Y and Z signals of the CIE
or L, a and b signals of the CIE. Output data depends on the
contents (the type of the image input apparatus) of the LUT 12
composed of only characteristic points. Output data is R, G and B
signals of a scanner, R, G and B signals of a monitor, C, M and Y
signals of a printer, R, G and B signals of a CIE, X, Y and Z
signals of the CIE or L, a and b signals of the CIE.
[0091] The LUT 12 composed of only characteristic points is similar
to the LUT 12 which is produced by the color characteristic
description apparatus 2 of the image input apparatus 1 according to
the first embodiment. Therefore, the LUT 12 is omitted from
description.
[0092] The image-data converting means 23 will now be described.
Similarly to the image-data converting means 15 according to the
first embodiment, input image data is converted into output image
data. The difference lies in that the LUT 12 composed of only
characteristic points is used to perform the conversion process.
Referring to FIG. 11, the difference will now be described. An
alternate long and short dash line shown in FIG. 11 indicates a
process for performing the conversion process by using the
multidimensional LUT 14. Arrows in the form of dashed lines
indicate the multidimensional LUT 14 according to the first
embodiment. A solid line shown in FIG. 11 indicates a conversion
process using the LUT 12 composed of only characteristic points.
When the conversion process is performed by using the
multidimensional LUT 14, loss of information of inputs and outputs
indicated by the characteristic points is sometimes caused
depending on a method of selecting the grid points in the
multidimensional LUT 14. If the conversion process is performed by
using the LUT 12 composed of only characteristic points, the loss
of information of inputs and outputs indicated by the
characteristic points can be prevented.
[0093] As described above, the fourth embodiment is provided with
the image-data converting means 23 which uses the LUT 12, the
quantity of which is smaller than that of the multidimensional LUT
14. The LUT 12 is composed of only characteristic points of the
color characteristic of a color device (an image input apparatus).
Therefore, the characteristic of the device can be described by
only the LUT 12, the capacity of which is small and which is
composed of only characteristic points. Moreover, loss of
information indicated by the characteristic points of the
characteristic of the color device can be prevented when the
process is performed.
[0094] (Fifth Embodiment)
[0095] A fifth embodiment of the present invention will now be
described with reference to the drawings. FIG. 12 is a block
diagram showing a color management apparatus according to the fifth
embodiment of the present invention. Reference numeral 16
represents a color management apparatus according to the present
invention. Reference numeral 12 represents a LUT composed of only
characteristic points. Reference numeral 24 represents a table
development means for developing the LUT 12 composed of only
characteristic points into a multidimensional lookup table. The
table development means 24 performs an operation which is different
from that of the table development means 13 according to the first
embodiment. Reference numeral 25 represents a multidimensional LUT
25 which is operated differently from the multidimensional LUT 14
according to the first embodiment. Reference numeral 26 represents
an image-data converting means which employs the multidimensional
LUT 25 to convert input image data into output image data.
[0096] Input image data of the image-data converting means 26
varies depending upon the type of the image input apparatus. Input
image data is digital image signals, such as R, G and B signals of
a scanner, R, G and B signals of a monitor, R, G and B signals of a
CIE, X, Y and Z signals of the CIE or L, a and b signals of the
CIE. On the other hand, output data depends on the contents of the
multidimensional LUT 25 (the type of the image input apparatus),
that is, the type of the image input apparatus. Output data above
is R, G and B signals of a scanner, R, G and B signals of a
monitor, C, M and Y signals of a printer, R, G and B signals of a
CIE, X, Y and Z signals of the CIE or L, a and b signals of the
CIE.
[0097] The LUT 12 composed of only characteristic points is similar
to the LUT 12 produced by the color characteristic description
apparatus 2 of the-digital camera 1 according to the first
embodiment and composed of only characteristic points. Therefore,
the LUT 12 is omitted from description.
[0098] The table development means 24 will now be described.
Similarly to the table development means 13 according to the first
embodiment, the table development means 24 develops the LUT 12
composed of only characteristic points into a multidimensional
lookup table. The difference lies in that development into the
usual multidimensional LUT 14 according to the first embodiment is
not performed. In this embodiment, development into a new
multidimensional LUT 25 according to the present invention is
performed.
[0099] Initially, the new multidimensional LUT 25 will now be
described. The multidimensional LUT 14 is a LUT which is composed
of pairs of inputs and outputs at grid points formed by equal
division as shown in FIG. 3. When the LUT 12 composed of only
characteristic points is developed into the multidimensional LUT
14, loss of information of the characteristic points is sometimes
caused as described with reference to FIG. 11. The new
multidimensional LUT 25 according to the fifth embodiment is a
multidimensional lookup table which is able to prevent loss of
information of the characteristic points. Referring to FIG. 13, the
new multidimensional LUT 25 will now be described.
[0100] The new multidimensional LUT 25 is characterized in that
grid points obtained by combining a plurality of division points is
used. As a result, the characteristic points can be included in the
grid points without exception. An assumption is made that the
characteristic point is an input point having number 5. When all of
equal division points are made to be grid points as shown in FIG.
3, a method may be employed in which points obtained by division
into eight sections are made to be the grid points. According to
the fifth embodiment, grid points are composed by combining
division into four sections and that into eight sections, as shown
in FIG. 13. That is, the grid points are formed by fine division in
a region adjacent to the characteristic points. On the other hand,
great division is performed to form the grid points in a region in
which no characteristic point exists. As a result, the
multidimensional LUT 25 can be realized which is capable of
preventing enlargement of the volume of the LUT and loss of
information of the characteristic points. FIG. 14 shows change of
the multidimensional LUT 14 shown in FIG. 11 and according to the
first embodiment to the new multidimensional LUT 25 according to
the fifth embodiment.
[0101] The table development means 24 develops the LUT 12 composed
of only characteristic points into the new multidimensional LUT 25.
The table development means 24 examines the relationships, such as
the distances between the characteristic points and the grid
points. Thus, the table development means 24 obtains grid points
formed by combining a plurality of division points which contain
the characteristic points without exception and with which the
volume can be minimized so as to constitute the new
multidimensional LUT 25. Since the multidimensional LUT 25 has the
structure that the plurality of divisions are combined, information
of the grid point distance (the distance in units of shortest
distance among grid points of the input points) to the adjacent
grid point and adjacent grid point information of an interpolation
method with respect to an adjacent grid point are simultaneously
described.
[0102] FIGS. 15A and 15B show a data format for one grid point of
the multidimensional LUT 14 and the 25. FIG. 15A shows a data
format of one grid point of the multidimensional LUT 14, and FIG.
15B shows a data format of one grid point of the new
multidimensional LUT 25.
[0103] The image-data converting means 26 will now be described.
Similarly to the image-data converting means 15 according to the
first embodiment, the image-data converting means 26 converts input
image data into output image data. The difference lies in that the
new multidimensional LUT 25 is used to perform the conversion
process. The new multidimensional LUT 25 includes LUT output data
al and adjacent grid point information data a2. Initially, input
image data is used to obtain LUT data corresponding to grid points
which are used in the new multidimensional LUT 25. The LUT data
format a has a structure as described with reference to FIGS. 15A
and 15B. In accordance with LUT output data al of the obtained grid
point and LUT output data al of the adjacent grid point,
interpolation information of adjacent grid point information data
a2 and information of the distance between grid point are used to
convert input image data into output image data.
[0104] As described above, the fifth embodiment has the process for
converting the LUT 12 which is composed of only characteristic
points of the characteristic of the color device and the volume of
which is small into the new multidimensional LUT 25. The table
development means 24 performs the conversion into the new
multidimensional LUT 25 with which loss of the characteristic
points can be prevented and which has adjacent grid point
information data a2. Therefore, the LUT 12 composed of only
characteristic points having a small volume is able to describe the
characteristic of the device. Moreover, loss of information
indicated by the characteristic points of the characteristic of the
device can be prevented when a process is performed.
[0105] (Sixth Embodiment)
[0106] A sixth embodiment of the present invention will now be
described. FIG. 16 is a block diagram showing the overall structure
of the sixth embodiment of the present invention. Reference numeral
1 represents a digital camera which is an image input apparatus.
Reference numeral 2 represents a color characteristic description
apparatus composed of a multidimensional LUT producing means 2b for
producing a multidimensional LUT 14 by a known method of least
squares in accordance with the color characteristic of the digital
camera which has been measured by a calorimeter. Moreover, the
color characteristic description apparatus 2 is composed of a
compressed multidimensional LUT means 2d for compressing the
multidimensional LUT 14 produced by the multidimensional LUT
producing means 2b so as to produce a multidimensional LUT 27. The
color characteristic description apparatus 2 produces color
characteristic data having the multidimensional LUT 27 and an
identifier 29 for identifying a restoring and repairing method of
the multidimensional LUT 27. The structure of color characteristic
data is shown in FIG. 17.
[0107] Referring to FIG. 17, reference numeral 17 represents color
characteristic data according to this embodiment. Reference numeral
27 represents the compressed multidimensional lookup table which is
an element of color characteristic data 17. Reference numeral 29
represents the identifier which is an element of color
characteristic data 17 and which identifies a repairing and
restoring method.
[0108] Reference numeral 3 represents a data processing portion for
converting an image photographed by the digital camera into digital
image data. Reference numeral 4 represents a synthesizer for
synthesizing color characteristic data 17 having the
multidimensional LUT 27 and the identifier 29 indicating the
restoring and repairing method for the multidimensional LUT 27 and
the image data 20 with each other so as to produce an image data
format.
[0109] The multidimensional LUT means 2d compresses the
multidimensional LUT 14 by a known compressing method, for example,
a compressing method which is able to perform reversible
conversion, such as an adaptive coding method or a compression
library management method (LHA), or a FBTC method (refer to
Japanese Patent Laid-Open No. 6-292027. By using the
above-mentioned compressing method adaptable to image compression,
the multidimensional LUT 14 is compressed. When the above-mentioned
compressing method is employed, the volume of the multidimensional
LUT 14 can be reduced. Thus, conversion into the multidimensional
LUT 27 having all of information items which have been compressed
can be performed.
[0110] Reference numeral 10 represents a color printer which is an
image output apparatus for printing an image photographed by the
digital camera 1. Reference numeral 11 represents a separator for
separating the image data format transmitted from the digital
camera 1 into image data 20 and color characteristic data 17.
Reference numeral 27 represents a multidimensional LUT of color
characteristic data 17 produced by the color characteristic
description apparatus 2. Reference numeral 28 represents a
restoring means for restoring the multidimensional LUT 27 into the
multidimensional LUT 14 by using an identifier for identifying a
restoring and repairing method for color characteristic data.
Reference numeral 14 represents the restored multidimensional LUT.
Reference numeral 15 represents an image-data converting means for
converting input image data signal separated by the separator 11
into an output signal by using the multidimensional LUT 14. The
separator 11, the restoring means 28, the multidimensional LUT 14
and the image-data converting means 15 constitute the color
management apparatus 16.
[0111] A signal transmitted from the color management apparatus 16
is processed in the color printer 10 so as to be printed, similarly
to the conventional structure.
[0112] Input image data of the image-data converting means 15
varies depending upon the type of the image input apparatus. Input
image data is digital image signals, such as R, G and B signals of
a scanner, R, G and B signals of a monitor, R, G and B signals of a
CIE, X, Y and Z signals of the CIE or L, a and b signals of the
CIE. On the other hand, output data of the image-data converting
means 15 depends on the contents of the multidimensional lookup
table LUT 13 (the type of the image input apparatus). Output data
above is R, G and B signals of a scanner, R, G and B signals of a
monitor, C, M and Y signals of a printer, R, G and B signals of a
CIE, X, Y and Z signals of the CIE or L, a and b signals of the
CIE.
[0113] The restoring means 28 is a restoring method adaptable to
the compressing method employed when the compressed
multidimensional LUT 27 has been produced with the identifier 29
indicating the restoring and repairing method of color
characteristic data 17. Thus, the compressed multidimensional LUT
27 is restored to the multidimensional LUT 14.
[0114] Since the image-data converting means 15 is structured
similarly to that according to the first embodiment, the image-data
converting means 15 is omitted from description.
[0115] As described above, the sixth embodiment has the process for
restoring the multidimensional LUT 27 formed by compressing the
multidimensional LUT into the multidimensional LUT 14 by the
restoring means 28. Therefore, the color characteristic of the
device can be described by the compressed multidimensional LUT 27
having a small volume.
[0116] (Seventh Embodiment)
[0117] A seventh embodiment of the present invention will now be
described. FIG. 18 is a diagram showing the structure of color
characteristic data according to the seventh embodiment of the
present invention. Reference numeral 27 represents a compressed
multidimensional LUT which is an element of color characteristic
data 17. Reference numeral 30 represents software which is an
element of color characteristic data 17 and which performs a
restoring process.
[0118] The operation of the color management apparatus 16 which
uses color characteristic data 17 according to the seventh
embodiment will now be described such that the sixth embodiment is
taken as an example. The compressed multidimensional LUT 27 in
color characteristic data 17 is used as the compressed
multidimensional LUT 27 in the color management apparatus 16
according to the sixth embodiment. Software 30 in the color
characteristic data 17 for performing the restoring process is
loaded as software for the restoring means 28 so as to be executed.
Thus, table restoration is performed so that the multidimensional
LUT 14 is restored. Then, the image-data converting means 15 uses
the multidimensional LUT 14 so as to convert input image data into
output image data.
[0119] As described above, the seventh embodiment has the structure
that color characteristic data 17 is composed of the compressed
multidimensional LUT 27 and the software 30 for performing the
restoring process. Therefore, the color management apparatus 16
according to the sixth embodiment and arranged to use the
compressed multidimensional LUT 27 is able to change the restoring
process, which is performed by the restoring means 28, to be
adaptable to color characteristic data 17. Thus, the color
management apparatus 16 can be operated as described above.
[0120] (Eighth Embodiment)
[0121] An eighth embodiment of the present invention will now be
described. FIG. 19 is a diagram showing the structure of color
characteristic data according to the eighth embodiment of the
present invention. Reference numeral 17 represents color
characteristic data according to the present invention. Reference
numeral 27 represents a compressed multidimensional LUT which is an
element of color characteristic data 17. Reference numeral 29
represents an identifier which is an element of color
characteristic data 17 and which indicates a restoring method.
Reference numeral 30 represents software which is an element of
color characteristic data 17 and which performs the restoring
process.
[0122] The operation of a color management apparatus using color
characteristic data 17 according to the eighth embodiment will now
be described such that the sixth embodiment is taken as an example.
The compressed multidimensional LUT 27 in color characteristic data
17 is used as the compressed multidimensional LUT 27 in the color
management apparatus 16 according to the sixth embodiment. A CPU
(not shown) or the like uses the identifier 29 indicating the
restoring method which is loaded as software for the restoring and
developing means 28 to perform the restoring and developing
process. The restoring and developing means 28 performs the
restoring and developing process so that the table is restored.
Thus, restoration to the multidimensional LUT 14 is performed. The
image-data converting means 15 uses the multidimensional LUT 14 to
convert input image data into output image data.
[0123] As described above, the eighth embodiment has the structure
that color characteristic data 17 is composed of the compressed
multidimensional LUT 27, the identifier 29 indicating the restoring
method and software 30 for performing the restoring and developing
process. Therefore, the color management apparatus 16 using the
compressed multidimensional LUT 27 according to the sixth
embodiment can be arranged such that an appropriate restoring
process is performed if an appropriate restoring method exists in
the restoring and developing means 28. If any appropriate restoring
method does not exist, the software 30 for performing the restoring
and developing process is loaded. Thus, the restoring process is
performed to cause the color management apparatus 16 to be
operated.
[0124] (Ninth Embodiment)
[0125] A ninth embodiment of the present invention will now be
described with reference to a drawing. FIG. 20 is a block diagram
showing a color management apparatus according to the ninth
embodiment of the present invention. Reference numeral 16
represents a color management apparatus according to the present
invention. Reference numeral 12 represents a lookup table LUT
composed of only characteristic points. Reference numeral 13
represents a table development means for developing the LUT
composed of only characteristic points into a multidimensional
lookup table. Reference numeral 14 represents a multidimensional
LUT. Reference numeral 31 represents a table recording means for
recording the multidimensional LUT 14 in a memory (not shown) or
the like. Reference numeral 32 represents the recorded
multidimensional LUT. Reference numeral 15 represents an image-data
converting means for converting input image data into output image
data by using the recorded multidimensional LUT 32. Reference
numeral 33 represents an update determining means for determining
whether or not update to the lookup table LUT composed of only
characteristic points has been performed.
[0126] Input image data of the image-data converting means 15
varies depending upon the type of the image input apparatus. Input
image data is digital image signals, such as R, G and B signals of
a scanner, R, G and B signals of a monitor, R, G and B signals of a
CIE, X, Y and Z signals of the CIE or L, a and b signals of the
CIE. On the other hand, output data depends on the contents of the
contents of the multidimensional LUT 14 (the type of the image
input apparatus),that is, the type of the image input apparatus.
Output data above is R, G and B signals of a scanner, R, G and B
signals of a monitor, C, M and Y signals of a printer, R, G and B
signals of a CIE, X, Y and Z signals of the CIE or L, a and b
signals of the CIE.
[0127] The LUT 12 composed of only characteristic points, the table
development means 13 and the multidimensional LUT 14 are structured
similarly to those according to the first embodiment. The table
development means 13 is operated when the update determining means
33 has determined that the LUT 12 composed of only characteristic
points has been updated, for example, the type of the image input
apparatus is different and therefore the color characteristic is
different.
[0128] The table recording means 31 is operated when the update
determining means 33 has determined that the LUT 12 composed of
only characteristic points has been updated. The table recording
means 31 records-the developed multidimensional LUT 14 as the
recorded multidimensional LUT 32 recorded in a memory or the
like.
[0129] The image-data converting means 15 is operated similarly to
that according to the first embodiment. The difference lies in that
the recorded multidimensional LUT 32 is employed as the LUT. The
image-data converting means 15 is operated when input image data is
supplied.
[0130] As described above, the ninth embodiment has the structure
that the table development means 13 and the table recording means
31 are operated when the update determining means 33 determines
that the LUT 12 composed of only characteristic points has been
updated. Therefore, image data can be converted in only a
processing period of time of the image-data converting means 15
when the conversion is performed. Therefore, the conversion process
can quickly be completed.
[0131] (Tenth Embodiment)
[0132] A tenth embodiment of the present invention will now be
described. The tenth embodiment of the present invention is
characterized by a method of efficiently examining the
characteristic points of a color device (an image input apparatus)
when a LUT 12 composed of only characteristic points is produced.
FIG. 21 is a graph showing the color characteristic of the color
device for describing the tenth embodiment. The graph is expressed
by using L*a*b color coordinate system regulated by International
Illumination Association. The graph shows the color characteristic
of a color device structured such that 0step indicates white. The
gradient of the color is raised in proportion to the number of the
step. Highest color saturation is realized at 8step. A variety of
colors are reproduced which are measured by a colorimeter,
resulting as shown in FIG. 21. In the drawing, color indicated with
a dashed line given name is the characteristic point according to
the first embodiment.
[0133] The foregoing colors are fundamental colors for the color
device. The fundamental colors are colors realized by combining
primary colors (RGB for a monitor and CMY (K) for a printer) for
the color device. FIGS. 22A to 22C show the fundamental colors. The
fundamental color are classified into primary colors, secondary
colors, . . . , n-order colors (n is the number of primary colors)
by combining the colors. The signals of the various colors have the
same sizes. FIGS. 22A to 22C show the fundamental colors of the
color device composed of three primary colors, that is, RGB. The
heights of the signals indicate the size of the primary color
signals. The primary colors are red, green and blue, secondary
colors are yellow, magenta and cyan and the tertiary color is gray.
When a variety of color devices are examined, the fundamental
colors of the color device are included in the characteristic
points. That is, when the fundamental colors of the color device
are selected, the characteristic points can be examined.
[0134] As described above, the sixth embodiment has the structure
that the fundamental colors composed by combining the primary
colors of the color device having the same signal value are made to
be the points indicating the relationships between inputs and
outputs which are determined to be impossible to be developed in
the table development process, that is, the characteristic points.
Therefore, the characteristic points of the color device can
efficiently be examined.
[0135] (Eleventh Embodiment)
[0136] An eleventh embodiment of the present invention will now be
described with reference to the drawings. Referring to FIG. 23,
reference numeral 11 represents a separator for separating an image
data format transmitted from the digital camera 1 into image data
20 and color characteristic data 17. Reference numeral 16
represents a color management apparatus according to the eleventh
embodiment. Reference numeral 12 represents a LUT composed of only
characteristic points. Reference numeral 13 represents a table
development means for developing the LUT 12 composed of only
characteristic points into a multidimensional LUT 14. Reference
numeral 14 represents the multidimensional LUT developed by the
table development means 13. Reference numeral 34 represents an ICC
profile converting means. Reference numeral 35 represents an ICC
profile. Reference numeral 36 represents an image-data converting
means using the ICC profile 35.
[0137] FIG. 24 is a diagram showing the structure of color
characteristic data 17 for use-in the eleventh embodiment of the
present invention, data being produced by the color characteristic
description apparatus 2 according to the first embodiment.
Reference numeral 17 represents color characteristic data according
to the present invention. Reference numeral 12 represents a LUT
which is an element of color characteristic data 17 and which is
composed of only characteristic points. Reference numeral 18
represents an identifier which is an element of color
characteristic data 17 and which indicates a table development
method. Reference numeral 21 represents software which is an
element of color characteristic data 17 and which performs the
table development. Reference numeral 37 represents software for
converting a multidimensional LUT subjected to the table
development process into a known ICC profile.
[0138] The operation of the eleventh embodiment will now be
described with reference to FIGS. 23 and 24. The LUT 12 included in
color characteristic data 17 and composed of only characteristic
points is used as the LUT 12 included in the color management
apparatus 16 shown in FIG. 23 and composed of only characteristic
points. The table development means 13 uses the identifier 18
indicating the table development method to cause a CPU (not shown)
or the like to select a table development method. If a
corresponding table development method does not exist, the software
21 included in color characteristic data 17 and arranged to perform
the table development is loaded as software for the table
development by the table development means 13. Then, the table
development process is performed so that the table development is
carried out. Thus, development to the multidimensional LUT 14 is
performed. Then, software 37 for converting the multidimensional
LUT 14 subjected to the table development process into a known ICC
profile by the ICC profile converting means 34 is loaded and
executed. Thus, conversion into the known ICC profile 35 is
performed. Then, the image-data converting means 36 uses the ICC
profile 35 to perform the image data conversion process so that
input image data is converted into output image data.
[0139] As described above, the eleventh embodiment has the
structure that color characteristic data 17 is composed of the LUT
12 composed of only characteristic points, the identifier 18
indicating the table development method, the software 21 for
performing the table development process and the software 37.
Therefore, the color management apparatus 16 using the LUT 12
according to the first embodiment and composed of only
characteristic points is able to perform the table development
process by an appropriate table development method if the
appropriate method exists in the table development means 13. If no
appropriate table development method exists, the software 21 for
performing the table development process is loaded so that the
table development process is performed. Thus, the ICC profile can
be converted. Thus, the image conversion color management apparatus
can be operated with the ICC profile.
[0140] (Twelfth Embodiment)
[0141] A twelfth embodiment of the present invention will now be
described. Referring to FIG. 25, reference numeral 11 represents a
separator for separating an image data format transmitted from the
digital camera 1 into image data 20 and color characteristic data
17. Reference numeral 27 represents a compressed multidimensional
LUT of color characteristic data 17 produced by the color
characteristic description apparatus 2. Reference numeral 28
represents a restoring means for restoring the compressed
multidimensional LUT 27 into the multidimensional LUT 14 by using
the identifier 29 indicating the restoring and repairing method for
color characteristic data. Reference numeral 14 represents a
multidimensional LUT restored by the restoring means 28. Reference
numeral 34 represents an ICC profile converting means for
converting the multidimensional LUT 14 into an ICC profile.
Reference numeral 35 represents the ICC profile converted by the
ICC profile converting means. Reference numeral 36 represents an
image-data converting means for converting an input image data
signal separated by the separator 11 into an output signal.
[0142] FIG. 26 is a diagram showing the structure of color
characteristic data 17 for use in the twelfth embodiment of the
present invention, color characteristic data 17 being produced by,
for example, the color characteristic description apparatus 2
according to the sixth embodiment. Reference numeral 17 represents
color characteristic data according to the present invention.
Reference numeral 27 represents a compressed multidimensional LUT
which is an element of color characteristic data 17. Reference
numeral 29 represents an identifier which is an element of color
characteristic data 17 and which indicates a restoring method.
Reference numeral 30 represents software which is an element of
color characteristic data 17 and which performs the restoring
process. Reference numeral 37 represents software for converting
the multidimensional lookup table subjected to the table
development process into a known ICC profile.
[0143] The operation of the twelfth embodiment will now be
described with reference to FIG. 25. The compressed
multidimensional LUT 27 in color characteristic data 17 is used as
the multidimensional LUT 27 in the color management apparatus 16
shown in FIG. 25. The restoring means 28 uses the identifier 29
indicating the restoring method to cause a CPU (not shown) or the
like to select a restoring method. If a corresponding restoring
method does not exist, the software 30 contained in color
characteristic data 17 and arranged to perform the restoring
process is loaded as the software for the restoring process. Then,
the restoring means 28 performs the restoring process so that the
table is restored. Thus, restoration to the multidimensional LUT 14
is performed. Then, the software 37 for causing the ICC profile
converting means 34 to convert the multidimensional LUT 14
subjected to the restoring process into the known ICC profile is
loaded and executed. Thus, conversion into the known ICC profile 35
is performed. Then, the image-data converting means 36 uses the ICC
profile 35 to perform an image data conversion process. As a
result, input image data is converted into output image data.
[0144] As described above, the twelfth embodiment has the structure
that color characteristic data 17 is composed of the compressed
multidimensional LUT 27, the identifier 29 indicating the restoring
method, the software 30 for performing the restoring process and
the software 37. Therefore, the color management apparatus 16
according to the sixth embodiment and arranged to use the
compressed multidimensional LUT 27 is able to perform an
appropriate process if an appropriate restoring method exists. If
no appropriate method exists, the software 30 for performing the
restoring process is loaded so that the restoring process is
performed. Then, the software 37 for performing conversion into the
ICC profile is able to perform the conversion into the ICC profile.
Thus, even a color management apparatus for converting an image
with the ICC profile can be operated.
[0145] (Thirteenth Embodiment)
[0146] A thirteenth embodiment of the present invention will now be
described with reference to the drawings. The thirteenth embodiment
has a structure constituted by separating the color management
apparatus 16 from the image output apparatus 10 so that an
independent image converging apparatus is formed. FIG. 27 is a flow
chart of data in the image converging apparatus according to the
thirteenth embodiment of the present invention. Reference numeral
38 represents image data format (1) of color characteristic data 17
and image data 20 which are input to the image converging
apparatus. Reference numeral 39 represents an image data format (2)
of color characteristic data 17a and image data 20a after the image
converting apparatus has converted image data 20. Reference numeral
40 represents the image converting apparatus according to the
thirteenth embodiment.
[0147] The shape of the image data format (1) 38 and that of the
image data format (2) 39 are similar to those shown in FIG. 7.
[0148] The operation will now be described. Image data 20 input to
the image converting apparatus 40 in the form of the image data
format 38 is subjected to a process, which is performed by the
color management apparatus 16, by the image converting apparatus 40
by using color characteristic data 17 corresponding to image data
31. Then, converted image data 20a and color characteristic data
17a adaptable to converted image data 20a are added to each other
so that data above is transmitted in the form of the image data
format 39.
[0149] As described above, the thirteenth embodiment has the
structure that the image converting apparatus 40 uses color
characteristic data 17 corresponding to image data 20 to perform
the process of image data 20, which is performed by each color
management apparatus 16 and which is input to the image converting
apparatus 40 in the form of the image data format 38. Then,
converted image data 20a and color characteristic data 17a
adaptable to converted image data 20a are added to each other so as
to be transmitted in the form of the image data format 39.
Therefore, converted image data 20a and color characteristic data
17a adaptable to image data 20a always exist in the form of a pair.
Thus, the following color process can efficiently be performed.
[0150] The color management apparatus 16 is separated from the
image output apparatus 10 so as to be the image converting
apparatus 40. Therefore, even an image output apparatus 10 which
does not incorporate the color management apparatus 16 is able to
process image data processed by the color characteristic
description apparatus to transmit data as an image when an output
of the image converting apparatus 40 is input.
[0151] When the image converting apparatus 40 is connected to a
plurality of image output apparatuses 10, the image converting
apparatus 40 can be shared.
[0152] (Fourteenth Embodiment)
[0153] A fourteenth embodiment of the present invention will now be
described with reference to the drawings. FIG. 28 is a flow chart
of data in an image converting apparatus according to the
fourteenth embodiment of the present invention. Reference numerals
38 and 39 represent the image data format (1) and the image data
format (2) according to the thirteenth embodiment. Reference
numeral 40 represents an image converting apparatus according to
the fourteenth embodiment. The image converting apparatus 40
includes a plurality of color characteristic data items 17 in the
forms shown in FIGS. 16, FIGS. 17 to 19 and FIGS. 21 to 24 and
having different color characteristics.
[0154] The operation will now be described. Image data 20 input to
the image converting apparatus 40 in the form of the image data
format 32 is processed by the image converting apparatus 40. The
process, which is performed by each of the color management
apparatus 16, is performed by using color characteristic data 17
corresponding to image data 20 and color characteristic data 17 in
the image converting apparatus 40 selected by a CPU (not shown) or
the like. Also color characteristic data 17 in the image converting
apparatus 40 includes color characteristic data included in the
image data format (1). When the CPU selects color characteristic
data suitable to a purpose, a process except for the process
regulated by the image data format (1) can be performed. Converted
Image data 20a and color characteristic data 17 suitable to
converted image data 20a are added to each other so that data is
transmitted in the form of the image data format 39.
[0155] As described above, the fourteenth embodiment has the
structure that the image converting apparatus 40 performs the
process which is performed by each color management apparatus 16.
The image converting apparatus 40 processes image data 20 input to
the image converting apparatus 40 in the form of the image data
format 38 by using color characteristic data 17 corresponding to
image data 20 and color characteristic data 17b in the image
converting apparatus 40 selected by a CPU (not shown) or the like.
Thus, a portion except for converted image data 20a and color
characteristic data 17a suitable to converted image data 20a is
included. Since data is output in the form of the image data format
39, conversion into image data having various color characteristics
by the number of color characteristic data 17b included in the
image converting apparatus 40 can be performed.
[0156] When color characteristic data is formed into data including
information about a light source, a single image reproducing
apparatus connected as a next apparatus is able to reproduce images
by dint of different light sources.
[0157] Although the foregoing embodiments are structured to convert
color image data, the present invention may be applied to image
data having a single halftone color.
[0158] As described above, according to the first aspect of the
present invention, color characteristic data is composed of a LUT
composed of only characteristic points. Therefore, the color
management apparatus using the LUT composed of only characteristic
points to convert input image data into output image data is able
to obtain precise color characteristic data without enlargement of
the volume of color characteristic data. Thus, the operation of the
color management apparatus can appropriately be performed.
[0159] The second aspect of the present invention has the structure
that the fundamental colors constituted by combining primary colors
of a color device having the same signal value are made to be the
points indicating the relationships between inputs and outputs
which are determined to be impossible to be developed in the table
development process, that is, the characteristic points. Therefore,
an effect can be obtained in that the characteristic points of a
color device can efficiently be examined.
[0160] The third aspect of the present invention has the structure
that color characteristic data is composed of the LUT composed of
only characteristic points and the identifier indicating the table
development method. Therefore, the operation of a color management
apparatus using the LUT composed of only characteristic points and
arranged to convert input image data into output image data can
appropriately be performed.
[0161] A fourth aspect of the present invention has the structure
that color characteristic data is composed of the LUT 21 composed
of only characteristic points and the software for performing the
table development process. Thus, an effect can be obtained in that
the table development process of the color management apparatus
using -the LUT composed of only characteristic points and arranged
to convert input image data into output image data can be changed
to correspond to color characteristic data.
[0162] The fifth aspect of the present invention has the structure
that color characteristic data is composed of the LUT composed of
only characteristic points, the identifier indicating the table
development method, the software for performing the table
development process and the ICC profile converting software.
Therefore, the color management apparatus using the LUT composed of
only characteristic points and arranged to convert input image data
into output image data is able to perform an appropriate table
development process if the appropriate table development method
exists. If no appropriate table development method exists, the
software for performing the table development process is loaded to
perform the table development process. Then, conversion into the
ICC profile can be performed. Therefore, an effect can be obtained
in that even a color management apparatus for converting an image
with the ICC profile can be operated.
[0163] The sixth aspect of the present invention has the structure
that color characteristic data is composed of the compressed
multidimensional LUT and the identifier indicating a restoring
method. Therefore, an effect can be obtained in that the operation
of the color management apparatus using the compressed
multidimensional LUT and arranged to convert input image data into
output image data can appropriately be performed.
[0164] The seventh aspect of the present invention has the
structure that color characteristic data is composed of the
compressed multidimensional LUT and the software for performing the
restoring process. Therefore, an effect can be obtained in that the
color management apparatus using the compressed multidimensional
LUT and arranged to convert input image data into output image data
can be operated such that the restoring process is changed to
correspond to color characteristic data.
[0165] The eighth aspect of the present invention has the structure
that color characteristic data is composed of the compressed
multidimensional LUT, the identifier indicating a restoring method,
the software for performing the restoring process and the ICC
profile converting software. Therefore, an effect can be obtained
in that the color management apparatus using the compressed
multidimensional LUT and arranged to convert input image data into
output image data is able to perform an appropriate restoring
process if the appropriate restoring method exists. If appropriate
restoring method does not exist, the software for performing the
restoring process is loaded to perform the restoring process. Then,
conversion into the incorporate can be performed. Thus, the color
management apparatus for converting an image with the ICC profile
can be operated.
[0166] The ninth and sixteenth aspects of the present invention
incorporate the image data converting apparatus which uses the LUT,
the volume of which is smaller than the multidimensional LUT and
which is composed of only characteristic points of the color
characteristic of a color device so as to directly convert an image
signal. Therefore, an effect can be obtained in that the
characteristic of the device can be described with the LUT having a
small volume and which is composed of only characteristic points.
Moreover, loss of information indicated by the characteristic point
of the characteristic of the color device can be prevented. Thus,
all of information can be processed.
[0167] The tenth aspect of the present invention incorporates the
process for converting the LUT having a small volume as compared
with a multidimensional LUT and composed of only characteristic
points of the characteristic of a color device into the
multidimensional LUT by the table development process. Therefore,
an effect can be obtained in that the color management apparatus
can be operated by only the LUT having a small volume and composed
of only characteristic points of the characteristic of the
device.
[0168] The eleventh aspect of the present invention has the process
for converting the LUT having a small value and composed of only
characteristic points of the characteristic of a color device into
a new multidimensional LUT having data of information about
adjacent grid points for preventing loss of characteristic points.
Therefore, an effect can be obtained in that the characteristic of
the device can be described by only the LUT having a small volume
and composed of only characteristic points. Moreover, all of
information items indicated by the characteristic points of the
characteristic of the color device can be processed.
[0169] The twelfth aspect of the present invention has the
structure that information of the distances between grid points and
the interpolation method about the adjacent grid points in the
multidimensional lookup table is described together with LUT output
data. Therefore, different interpolation methods can be employed
for each small region composed of the adjacent grid points. Thus,
an effect can be obtained in that an accurate interpolation process
can be performed.
[0170] The thirteenth aspect of the present invention has the
restoring process for restoring a compressed multidimensional LUT
formed by compressing a multidimensional LUT to the
multidimensional LUT. Therefore, an effect can be obtained in that
the color characteristic of the device can be described with the
compressed multidimensional LUT having a small volume.
[0171] The fourteenth aspect of the present invention has the
structure that the table development process and the table
recording process are performed when the lookup table LUT composed
of only characteristic points has been updated. Therefore, when
image data is converted, the conversion of image data can be
completed in only the processing period of time of the process for
converting image data. Therefore, an effect can be obtained in that
the conversion process can quickly be completed.
[0172] The fifteenth aspect of the present invention has the
structure that the image converting apparatus performs the process
of the color management apparatus. That is, the image converting
apparatus subjects image data which is input to the image
converting apparatus in the form of the image data format to the
process by using color characteristic data corresponding to image
data and color characteristic data in the image converting
apparatus selected by the CPU (not shown) or the like. Then,
converted image data and color characteristic data adaptable to
converted image data are added to each other so as to be
transmitted in the form of the image data format. Therefore,
selection of the CPU (not shown) enables conversion into image data
having a variety of color characteristics to be performed.
Moreover, an effect can be obtained in that also the color
characteristic of converted image data can be described and thus
the following color process can efficiently be performed.
* * * * *