Facsimile and static presentation processing – Static presentation processing – Attribute control
Reexamination Certificate
1997-06-26
2002-04-30
Mancuso, Joseph (Department: 2624)
Facsimile and static presentation processing
Static presentation processing
Attribute control
C358S515000, C358S518000, C382S167000
Reexamination Certificate
active
06381034
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image process apparatus and method which perform an under color removal process for inputted image data.
2. Related Background Art
In recent years, color printers applying various recording systems have been developed as output apparatuses for a color image. In these printers, an ink-jet recording apparatus has been widely used, because such apparatus has many advantages. That is, the ink-jet recording apparatus can be manufactured at low cost, can print a high-quality image on various kinds of recording media, can easily be made compact in size, and the like.
Numbers of image data which are outputted by such color printer frequently correspond to an output apparatus which utilizes a light emission element such as a CRT (cathode-ray tube) monitor or the like. Therefore, such image data are composed of R (red), G (green) and B (blue) signals.
The color printer converts such RGB signals into C (cyan), M (magenta) and Y (yellow) signals or C (cyan), M (magenta), Y (yellow) and K (black) signals, by using an image process means. An image process method which is performed by such image process means has been proposed as U.S. patent application Ser. No. 08/711,953 filed on Sep. 6, 1996, by the same applicant as that of the present application.
FIG. 8
is block diagram for explaining a concept of such image process method proposed by the same applicant as that of the present application.
It is assumed that the image data consists of eight bits for each of RGB colors, and “eight bits” in the present application represents integers from 0 to 255.
The image data is inputted into an image input means
20001
and then R, G and B data each consisting of eight bits are transferred to a luminance and density conversion means
20002
. The luminance and density conversion means
20002
performs a luminance and density converting process on the R, G and B data to convert these data into C, M and Y data each consisting of eight bits.
Subsequently, a black component generation means
20003
generates a black component K on the basis of minimum values of the C, M and Y data. If it is assumed that a function to be used for calculating the minimum value is min( ), C
1
, M
1
, Y
1
and K
1
data each consisting of eight bits and outputted from the black component generation means
20003
are obtained by the following equations.
C
1
=C
M
1
=M
Y
1
=Y
K
1
=min(C, M, Y)
Subsequently, a masking means
20004
performs a masking process on the C
1
, M
1
, Y
1
and K
1
data to output C
2
, M
2
and Y
2
data.
Subsequently, an under color component separation means
20005
performs a process on the basis of following equations, to output C
3
, M
3
, Y
3
and U data.
U=min(C
2
, M
2
, Y
2
)
C
3
=C
2
−U
M
3
=M
2
−U
Y
3
=Y
2
−U
Subsequently, an under color process means
20100
generates C
4
, M
4
, Y
4
and K
4
data each consisting of eight bits, on the basis of the under color component data U. The under color process means
20100
is composed of a black component generation means
20006
, a cyan component generation means
20007
, a magenta component generation means
20008
and a yellow component generation means
20009
, and thus generates the C
4
, M
4
, Y
4
and K
4
data each consisting of eight bits by using functions KGR( ), CGR( ), MGR( ) and YGR( ) shown in FIG.
9
. That is, the following relation is satisfied.
C
4
=CGR(U)
M
4
=MGR(U)
Y
4
=YGR(U)
K
4
=KGR(U)
Subsequently, the C
3
, M
3
and Y
3
data outputted from the under color component separation means
20005
and the C
4
, M
4
and Y
4
data outputted from the under color process means
20100
are respectively synthesized by a cyan component output means
20011
, a magenta component output means
20012
and a yellow component output means
20013
, to respectively generate C
6
, M
6
and Y
6
data. Such processes are performed on the basis of following equations.
C
6
=C
3
+C
4
M
6
=M
3
+M
4
Y
6
=Y
3
+Y
4
In this case, if values of the C
6
, M
6
and Y
6
data are equal to or smaller than “0”, such values are determined as “0”. On the other hand, if these values are equal to or larger than “256”, such values are determined as “255”. On the basis of the C
6
, M
6
, Y
6
and K
4
data outputted through such processes, an output gamma correction means
20101
respectively output C
7
, M
7
, Y
7
and K
7
data each consisting of eight bits. The output gamma correction means
20101
is composed of a black output gamma correction means
20014
, a cyan output gamma correction means
20015
, a magenta output gamma correction means
20016
and a yellow output gamma correction means
20017
, and calculates the following equations by using functions KGAM( ), CGAM( ), MGAM( ) and YGAM( ).
C
7
=CGAM(C
6
)
M
7
=MGAM(M
6
)
Y
7
=YGAM(Y
6
)
K
7
=KGAM(K
4
)
The output gamma correction means performs the conversion to linearize the relation between the inputted values (i.e., C
6
, M
6
, Y
6
and K
4
data) and optical reflection densities of printed or outputted results. Ordinarily, each of the functions KGAM( ), CGAM( ), MGAM( ) and YGAM( ) shown in
FIG. 10
consists of 256 reference tables.
The functions CGR( ), MGR( ), YGR( ) and KGR( ) are set such that, in a case where the inputted image data satisfy the equations R=G=B, the printed results are obtained by an achromatic color. That is, such functions have structure for compensating for that, in a case where the image data represents gray scale, the printed result is also represented by the gray scale.
However, in such image process method, in a case where the inputted image data includes a color component other than the under color, there has been a problem that tonality or gradient (i.e., linearity between the inputted value and the outputted result) can not be compensated.
FIG. 11
is a view showing the relation between a blue signal (B) and an optical reflection density in the conventional image process apparatus.
In this case, the blue signal (B) has a value which represents blue components in the inputted C
2
, M
2
and Y
2
data (satisfying C
2
=M
2
and min(C
2
, M
2
, Y
2
)=Y
2
), and can be obtained by the following equation.
B=C
2
−Y
2
In
FIG. 11
, it can be understood that, in respect of cyan (C), the optical reflection density of a blue signal
127
is lower than that of a blue signal
255
. That is, the tonality in blue is not compensated. Especially, as the color component other than the achromatic color becomes large, i.e., as the inputted image becomes vivid, the tonality becomes.
Such a tendency is remarkable in an ink-jet record system. That is, in recording dot groups which represent a paper surface and an achromatic component (i.e., background color) by the gray scale, in a case where the recording dot groups are recorded such that the group representing the achromatic color component comes into contact with or overlaps the group representing the color component other than the achromatic color component on condition that the gray scale is optically compensated, such tendency is remarkable because the ink-jet record system changes the structure of a dye or a pigment on a surface of a recording medium.
SUMMARY OF THE INVENTION
An object of the present invention is to provide image process apparatus and method which compensate for tonality or gradient even in a case where a color component other than an under color component is included in input image data.
In consideration of a fact that the above-described tendency is remarkably seen in a blue region, an another object of the present invention is to compensate for the tonality especially in the blue region.
In order to achieve the above objects, an image process method is provided comprising:
an input step of inputting image data; and
an under color process step of performing an under color process according to a color region to which the imag
Iwasaki Osamu
Nishikori Hitoshi
Otsuka Naoji
Takahashi Kiichiro
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Mancuso Joseph
Tran Douglas
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