Computer graphics processing and selective visual display system – Computer graphics processing – Graph generating
Reexamination Certificate
1998-06-15
2001-07-31
Jankus, Almis R. (Department: 2672)
Computer graphics processing and selective visual display system
Computer graphics processing
Graph generating
Reexamination Certificate
active
06268867
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a color correction device, a color correction method and a color correction application device which applies the color correction method to control the color of the system to handle color image equipment.
BACKGROUND ART
FIG. 25
is a block diagram of a conventional color conversion method and a color conversion device, as disclosed for example in Japanese Unexamined Patent Publication No. 6-86059 and referred to herein as “conventional example 1.”
In
FIG. 25
, R
1
denotes an input &ggr;-correction part which performs &ggr;-correction of R, G and B signals read by a scanner part, R
2
denotes a pre-processing part which generates the minimum signal L by judging the magnitude of the &ggr;-corrected R, G and B signals, generates the differential signals X,Y between the input R, G and B signals and the minimum signal L, and generates the region selection signal S, R
3
denotes a color conversion parameter memory part which accumulates the color conversion parameter with the region selection signal S as the address, R
4
denotes an achromatic output signal generation part which generates the output signal P
1
corresponding to the achromatic input based on the minimum signal L, R
5
denotes an interpolation operating part which generates the output P
2
by interpolating the space to be formed by the minimum signal L and the differential signals X,Y by the triangular prismatic interpolation, R
6
denotes a limit processing part which performs the limit processing by adding the outputs P
1
, P
2
, R
7
denotes an output &ggr;-correction part which prepares the output signal P through &ggr;-correction of the limit-processed signal P
3
, and the output signals P generated by the output &ggr;-correction part R
7
are the ink quantity control signal of Y (yellow), M (magenta), C (cyan), etc., and supplied to the printer part after gradation processing in a systematic dither method by a dither processing part.
Conventional example 1 having the above-mentioned constitution is further explained as follows. The input &ggr;-correction part R
1
performs &ggr;-correction of the signal read by a scanner part with linear reflectance using a look-up table method of R=G=B for the achromatic input. The pre-processing part R
2
judges the magnitude of R, G and B signals based on the input R, G and B signals, sets the region selection signal S, and generates the minimum signal L and the differential signals X,Y between the minimum signal L and the input R, G and B signals.
The differential signals are determined as follows.
if ((R≧G) & (G≧B)), S=0, L=B, X=R−L, Y=G−L
if ((G>R) & (R≧B)), S=1, L=B, X=G−L, Y=R−L
if ((G≧B) & (B>R)), S=2, L=R, X=G−L, Y=B−L
if ((B>G) & (G>R)), S=3, L=R, X=B−L, Y=G−L
if ((B>R) & (R≧G)), S=4, L=G, X=B−L, Y=R−L
if ((R≧B) & (B>G)), S=5, L=G, X=R−L, Y=B−L
The color conversion parameter memory part R
3
is a memory with the region selection signal S as the address input, and four color conversion parameters a
s0
, a
s1
, a
s2
and a
s3
set for each below-mentioned unit triangular prism are accumulated as a set. The achromatic signal generation part R
4
outputs P
1
=R(=G=B) when R=G=B. The achromatic signal generation part R
4
comprises a through circuit where P
1
=L. The interpolation operating part R
5
obtains the output P
2
by performing interpolation of the triangular prism based on the minimum signal L and the differential signals X,Y from the pre-processing part R
2
and the color conversion parameters a
si
read from the color conversion parameter memory part R
3
.
Where the output value set at the apex (lattice point) of the triangular prism is T
i
(T
0
, T
1
, T
2
, T
3
), the output value P
2
in the coordinate (L, X, Y) in the unit triangular prism is calculated by the following formula, where the lattice point value on the L-axis (X=0, Y=0) is zero, and L, X and Y are assumed to be normalized to 0~1.
P
2
=T
0
·X+
(
T
2
−T
0
)·
L·X+T
1
·Y+
(
T
3
−T
1
)·
L·Y
The limit processing part R
6
adds the output value P
1
to the output value P
2
, and outputs the output value P
3
through the over-flow and under-flow processing. That means,
if (P
1
+P
2
>255), P
3
=255
if (P
1
+P
2
>0), P
3
=0
else P
3
=P
1
+P
2
The output &ggr;-correction part R
7
performs &ggr;-correction so that the reflection is linear during printing to the linear reflection signal P
3
. Correction is performed through table conversion.
FIG. 26
is a block diagram of APPARATUS FOR ADJUSTING HUE, CHROMINANCE, AND LUMINANCE OF A VIDEO SIGNAL USING MATRIX CIRCUITS disclosed in U.S. Pat. No. 5,333,070 and referred to herein as “conventional example 2.” In
FIG. 26
, Q
1
denotes a Y/C separation circuit which separates a video signal into a brightness signal Y and a color signal C, Q
2
denotes a decode circuit which converts the brightness signal Y and the color signal C into three primary colors R, G and B, Q
3
, Q
4
and Q
5
denote matrices of 3-row×3-column which perform color correction, Q
6
denotes an A/D converter which performs analog/digital conversion of the color-corrected signal, Q
7
denotes a frame memory which stores the digitized signal, Q
8
denotes a ROM which performs &ggr;-conversion, and Q
9
denotes a head of a printer. Q
10
is a regulation circuit which regulates the coefficient to the matrix circuit Q
4
.
The operation of the above-mentioned constitution is explained as follows. The operation of the matrix circuits Q
3
, Q
4
and Q
5
of 3-row×3-column which perform color correction is closely related to the present invention. The matrix circuit Q
3
converts the input signal from the RGB coordinate system to an S
fy
coordinate system. The S
fy
coordinate system is a coordinate system which includes the skin color axis S, the green color axis f, and the brightness axis Y. When the matrix circuit Q
3
is Mn, the matrix Mn on the skin color C
1
and the green color C
2
can be determined as indicated in the following formula.
(
100
0
Y
1
)
=
M
n
(
R
1
G
1
B
1
)
=
M
n
C
1
(
0
100
Y
2
)
=
M
n
(
R
2
G
2
B
2
)
=
M
n
C
2
The matrix circuit Q
4
performs the color regulation using S
fy
coordinate system, and outputs the signal expressed by the S
fy
coordinate system. When the matrix of the matrix circuit Q
4
is Mh, Mh can be expressed as follows.
M
h
=
(
h
11
h
12
0
h
21
h
22
0
h
31
h
32
1
)
The third row of the matrix Mh is (0 0 1) because the brightness of the achromatic signal is not changed. When the third row of the matrix Mh is (0 0 1), the role of each matrix element is as follows.
h
11
<1.0 Decrease the saturation of C
1
.
h
11
>1.0 Increase the saturation of C
1
.
h
21
<0 C
1
−hue in f-axis direction
h
21
>0 C
1
+hue in f-axis direction
h
31
<0 Decrease the brightness of C
1
.
h
31
>0 Increase the brightness of C
1
.
h
12
<0 C
2
−hue in S-axis direction
h
12
>0 C
2
+hue in S-axis direction
h
22
<1.0 Decrease the saturation of C
2
.
h
22
>1.0 Increase the brightness of C
1
.
h
32
<0 Increase the brightness of C
2
.
h
32
>0 Increase the brightness of C
2
.
Taking into consideration the above-mentioned role, the coefficients of the matrix Mh are determined according to the instruction of the regulation circuit Q
10
. The matrix circuit Q
5
converts the input signal from the S
fy
coordinate system to the RGB coordinate system. The matrix used here is the inverse matrix of the matrix Mn. Color regulation by the matrix circuit is performed by successively performing the processes by the matrix circuits Q
3
, Q
4
, Q
5
.
In the above-mentioned method and device for color conversion according to convention
Saito Masayuki
Sato Tsuneo
Cunningham G.
Jankus Almis R.
Mitsubishi Denki & Kabushiki Kaisha
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