JPS62180692A - Signal processing circuit for image pickup device - Google Patents

Abstract

PURPOSE:To attain a gamma correction with a circuit structure which is attached with a good video reproductivity, and is simplified comparatively, by synthesizing a gamma correction luminance signal from a gamma correction chrominance signal, and synthesizing an output luminance signal by adding the low-pass component of the gamma correction luminance signal and the high-pass component of the gamma correction luminance signal. CONSTITUTION:Gamma correction chrominance signals (RL)', (GL)' and (BL)' outputted from gamma correction circuits 4b, 4c, and 4d are converted to a gamma correction luminance signal ¦Y¦'=0.3(RL)'+0.59(GL)'+0.11(BL)', a gamma correction color difference signal C1'=(RL)'-¦Y¦', and a gamma correction color difference signal C2'=(BL)'-¦Y¦'. And above stated gamma correction luminance signal ¦Y¦', and color difference signals C1' and C2' are band-limited at LPFs 6b, 6c, and 6d having frequency bands of about 0.5mHz, and are changed to the low-pass component Y'L=¦Y¦'L of an output luminance signal Y', and output color difference signals C1'L, and C2'L, then going to an output luminance signal Y'=Y'L+Y'H=¦Y¦'L+(Y)'H.

Description

TECHNICAL FIELD The present invention relates to a signal processing circuit for an imaging device, and more particularly to an improvement in a gamma correction circuit thereof.

BACKGROUND OF THE INVENTION The output signal of an image pickup device using a solid-state image pickup device or an image pickup tube generally needs to be gamma corrected to compensate for the gamma characteristics of the cathode ray tube of a TV receiver. The gamma correction described above is generally performed by an imaging device. In the prior art, multiple gamma correction methods are used depending on the type of imaging device. The fidelity of the corrected color difference signals CI' and C2' was degraded. A gamma correction method for a conventional imaging device will be explained below.

The best first gamma correction method is to separate or combine the three primary color signals R, G, and B from the output signal of the imaging device, and then perform gamma correction on each of the three primary color signals R, G, and B to obtain gamma-corrected colors. The signals R', C', and B' are combined to produce the above-mentioned gamma-corrected color signals R', G''.

Gamma-corrected color difference signal Y'== 0, 3 R' from Bo
-1-0590'-1-0,I This is a method of synthesizing IIB' and two predetermined types of color difference signals CI'' and C2'.The above CI'.

C2° is generally R'-Y', H'-Y' or I', Q
1, the above three primary color signals R, G, I3 are separated from the output signals of the three imaging devices, and the output signals of the two imaging devices J (,, g, j;, It is well known that the signals are combined, separated from the output signal of one imaging device, or combined.This gamma correction method is hereinafter abbreviated as a three-primary-color gamma correction method.

The second gamma correction method separates the color difference signal Y and the 3Ki color signals R, G, and B from the output signal of the imaging device, and performs gamma correction on each of the above signals Y, R, G, and B, respectively. The signals (Y)', R', G', and R' are combined, and the gamma-corrected color difference signal (Y)° is used as the output color-difference signal Y', and the gamma-corrected fish signal R is
Two types of output color difference signals CI' from °, G゛, I3°,
This is a method of synthesizing C2°. Separating or combining the above color difference signal Y and the three primary color signals R, G, E (from the output signals of three or four types of imaging devices, or separating or combining them from the output signals of two imaging devices. It is well known to separate or combine the output signals of a single-chip or medium-tube color image pickup device.The advantage of this method is that the gamma correction circuit of the luminance committee Y has a wide band, and the gamma of the three primary color signals R, G, and B is The correction circuit should be narrow-band.This method will be abbreviated as the separate luminance three-primary color gamma correction IE method below.Generally, the three narrow-band gamma correction circuits include narrowband three-primary color signals R+, , , GL, BL are input,
And then gamma correction fall band fish signal y RL °,
c I, °, BL' should be output.

The third gamma correction method separates or combines the color difference signal Y11 signal R1 color signal>613 from the output signal of a single-chip or single-tube color imaging device, and then each of the above signals (Y)', R'
, +(°, output luminance signals rU, Y' and two types of output color difference signals C-01', C2° are combined.

Generally, the low frequency component YL of the above color difference signal Y and 1. Gamma-correct the low-frequency components RL and BL of the Uoshinshi '3iR1B, respectively, and synthesize the gamma-corrected low-frequency color difference signal YL' and the gamma-compensated 11 low-frequency color signals RL'' and RL',
Then, two types of output color difference signals C1' and C2° are synthesized from YL', RLo, and RL' in 1. Muchirun, the above-mentioned Kyushin pg, instead of ``), Uoshinso G
It is possible to use .

The fourth gamma correction method generates a color difference signal Y and two types of color difference signals R-Y from the output signal of a single-chip or single-tube color imaging device.
B-Y is separated or combined, and each of the above signals Y, R
-Y, B-Y are gamma-corrected and the gamma-corrected luminance signals are '(Y)', (R-Y)', 1-Y.
)°, part 1. The above gamma correction signal (Y)'
, (RY)'', ([3-Y)', the output color difference signal Y'' and two types of output color difference signals C1' and C2° are synthesized.

4. Separate the color difference signal Y and the low range color signals RL, BL from the output of the single-chip color solid-state imaging device, and the low range component YI of the above color difference signal Y; The color signal RL shown below.

Separating the low gamut color Ihat2·GL from II L and separately gamma correcting the above Rl, , C1, , B L is described, for example, in Japanese Patent Laid-Open No. 59-132286 filed by the present applicant. , is known in Japanese Patent Application Laid-Open No. 60-5678.

Furthermore, they also disclose that the high frequency component YH of the color difference signal Y mentioned above is subjected to gamma correction and a gamma corrected high frequency color difference signal (YT-1)'' is synthesized.

Therefore, in the above solid-state imaging device, the output color difference signal Y' is 0.3RL'+0.59CL'-10°]
] It is obvious that I3L'10 (YH')'.

Japanese Patent Laid-Open No. 60-3290 calculates a color difference signal Y from an output signal of a single-chip color solid-state imaging device, a low frequency component YL of the color difference signal Y,
Separate the low range color signals RL and BL, and - from the above low range color difference signal YL and low range color signal RL, BI7 to the low range color difference signal YL and low range color signal RL, BI7
The high frequency components YH of the above color difference signal Y are added to each of the low frequency color signals RL, CL, and BL for edge correction to produce color signals Rx=RL+YT-1, Gx=L+Y). I, Bx=BL.

+YH are combined and the above color signals Rx, Gx.

Bx is gamma-corrected and the low-frequency component Y' of the output color difference signal Y' is obtained.1. and two types of color difference signals C1'', C2
Disclose the synthesis of ゜. As the high frequency component of the output color difference signal Y, the high frequency component Y1-1 of the color difference signal Y described above is used.

Japanese Patent Laid-Open No. 60-125090 separates or combines a color difference signal Y and three primary color signals R, G, and B from the output signal of a solid-state imaging device, and performs gamma correction on each of the above signals Y, R, G, and H, respectively. The correction signals (Y)', R', G', and B' are combined, and the output color difference signal Y' is (Y)'.
It is also disclosed that two types of output color difference signals CI' and C2° are synthesized from the above-mentioned gamma-corrected color signals R', G', and B'. Therefore, in each of the above specific prior art examples,
Color difference signals Y and 3 are obtained from the output signal of the single-chip color solid-state imaging device.
Primary color signals R, G.

B, and the low frequency component Y' of the output color difference signal.
L or/and two types of output color difference signals CI', C2
It is well known to synthesize “.

DISCLOSURE OF THE INVENTION Despite the above prior art, conventional gamma correction methods have brightness errors or color difference errors, and the color or brightness reproducibility of reproduced signals has deteriorated. However, considering the future practical use of high-definition TV systems that compete with movies or electronic still cameras that compete with optical still cameras, it will be important to develop a gamma correction system that has improved image reproducibility. Therefore, the first object of the present invention is to develop a gamma correction method that has good image reproducibility. In addition, the gamma sleeve 1F has good image reproducibility and a relatively simple circuit structure.
It is important to develop a method. Therefore, the second 1-
The first purpose is to develop a gamma correction method that has good image reproducibility and a relatively simple circuit structure.4-To achieve the objective of item 14, this specification discloses two independent inventions. do. The inventions are disclosed together because they have the same purpose and are closely related.

Note that in this specification, the color difference signal Y is human body 0°3R, 0.59G10, IIR, YL, Yl (are its low frequency and high frequency components, and Y' is the gamma-corrected output. Y'L and Y'TI are the low-frequency and high-frequency components thereof.Similarly, R, G, and R are the respective primary color signals, and RL, GL, BL, and RI-1 are the primary color signals.
.

G II J3 TI are the low frequency and high frequency components of each primary color signal, respectively. The gamma-corrected luminance signal U(Y)' is a signal obtained by directly gamma-correcting the luminance signal Y, and (Y)' L
, (Y)°1-1 are its low and high frequency components. Gamma corrected brightness: Y Bi is approximately IY Dobby 0.
3R'-10°590'J O,] IR', and 1
Yl'L, :Yj'II are the low-frequency and high-frequency components of :Y.degree.

The J1ζ1 features of the present invention are described above.

(1) Separate or combine the color difference signal Y and the three primary colors (No. R, G, H) from the output of the imaging device ('rE'''J',
Then, each of the above signals Y, R, G, and R is gamma-corrected and gamma-corrected signals (Y)', R', G', B'' are synthesized, and the gamma correction signal (signal (Y) ',R
', G', H' to output color difference signal Y' and two types of output color difference signals C1', C2° are synthesized in the signal processing circuit of the imaging device.・R', G", B"
Synthesize the gamma-corrected luminance signal i';, IY jo from
And the low frequency component l of the above gamma-corrected color difference signal iYl'
Y:'! - and the high-frequency component (Y)'H of the above gamma-corrected color difference signal (Y)' (7) and add the output color difference signal y'-: Y
i" ■, + (y)" A signal processing circuit for an imaging device characterized by 11.

(2) Each of the signals y, R, c, and B separated or combined from the output signal of the imaging device has a band equal to that of the human body.
2. The signal processing circuit for an imaging device according to claim 1, characterized by JJl. (3) The first color difference signal Y, which is separated or combined from the output signal of the imaging device, has a wider band than the three primary color signals R, G, and B which are similarly separated or combined. The signal processing circuit of the imaging device described in 1.

(4) In a signal processing circuit of an imaging device that synthesizes a gamma-corrected output J color difference signal Y° from an output signal of the imaging device and two types of gamma-corrected output color difference signals CI' and C2', Separate or combine the three color signals Rx, GxJ (x) from the output signal of the imaging device, and - the above three color signals Rx, Gx,
BX is the high frequency component Y of the color difference signal Y, I-T and the three primary color signals R
1G, R each low frequency component R1,, GL, BI-
, addition signal (Rx-RL+YH, Gx=Gl, +YH
, Bx=BL-+Y I-1), and the above 3
Each of the color signals Rx, Gx, and BX is gamma-corrected to produce a gamma-corrected color signal Rx'.

Gx' and Rx' are synthesized, and from the gamma-corrected color signals Rx', Gx', and B , and the high-frequency component (Y)"H of the gamma-corrected color difference signal (Y)" obtained by directly gamma-correcting the above-mentioned color difference signal Y, or the above-mentioned gamma-corrected color signals Rx', Gx"
, B x', gamma-compensated IE color difference signal 1
Yxi'(= 0, 3 Rx'+0.

59 Gx'== 0, 118X') high frequency component I
Y
) 'H and IY circuit.

(5) Separate or combine the wideband color difference signal Y of the imaging device, perform gamma correction on the color difference signal Y described in 1 above, and combine the gamma signal + E - luminance transmission; - (Y)'. , and the high frequency component (Y) of the above gamma-corrected color difference signal (Y)°
The signal processing circuit 1 of the imaging device described in paragraphs 4 to 4 is characterized by a high-frequency component Y'II of the color difference signal Y' for outputting H, and 4. "leX', G
',Bx'' to output brightness (+-i'';,;Y
4. The signal processing circuit for an imaging device according to claim 4, characterized by combining both the low-frequency component Y'T and the high-frequency component Y'I! of 4.

(7), Deck Mahachi separates or combines the above three signals ';', -Rx, G x, I' (X) from the output signal of the middle tube color imaging device, and Deka no Shinkyu -
4- The low frequency component of is approximately the color difference signal Y.
7. A signal processing circuit for an imaging device according to item 6.

The detailed features and effects of the present invention will be explained below.

The drawbacks of the conventional gamma correction method will be explained below.

The first three primary color gamma correction method has good color reproducibility, but
This has the disadvantage that the reproducibility of high-frequency components of color difference signals deteriorates. This issue will be explained later. The disadvantage of the second gamma correction method is that the low frequency component of the output color difference signal Y' is (Y)'L=(0,
3R-+0 59G→01113)'I-, low-frequency component Y'L-=0 of accurate output color difference signal Y°
, 3 R' L -1-0, 590' T, + 0
.

3. In the third gamma correction method, which has the disadvantage of large luminance error and color error compared to 118'L, the low frequency component Y'L of the output luminance signal -1-; Complementary 1U: has the same drawbacks as the system, and also generates similar errors in the low-frequency components of the gamma-corrected color difference signals used for the two types of output color difference signals 0 and 02'. In the fourth gamma correction method, the low frequency component of the output color difference signal Y'' is
The gamma correction method generates the same error, and the two types of output color difference signals CBI and 02'' also generate errors.
-132286.60-5678, the color reproducibility is good, but the high frequency component Y' of the output color difference signal Y'
Since II is (Yl-T)'', the high frequency component of the output color difference signal has a luminance error. Since the high frequency component Y'I-1 or YII-I, the high frequency component Y'H of the output color difference signal has a luminance error.

Each independent and dependent invention is described in detail below.

Independent invention 1. Clay A 1 The present invention aims to improve the above-mentioned problems of the conventional gamma correction method, and has the following features. That is, the feature of the present invention is that the color difference signals Y and 3 extracted from the output of the imaging device are
The primary color signals R, G, and B are each gamma corrected to produce a gamma-corrected color difference signal (Y)° and a gamma-corrected color signal R', G',
R', and -14 gamma-corrected color signal R'
, G', H' to the low frequency component Y'L of the output color difference signal Y°
= IY i'l, and two types of output color difference Shinso C Bi,
C2゛ is synthesized, and the high-frequency component Y'H of the output color difference signal Y'' is combined with the high-frequency component Y'H of the gamma-corrected color difference signal (Y)°□
It is characterized by component (Y)'Fl and 4-roto. Therefore, the output color difference signal Y'-1v j'1-.(Y')'I
It becomes T. Naturally, the high frequency limit of iY loL is (Y)°1-
□ equal to the low frequency limit □ of 1. If you do this, you can do it again. In claim 2, the three primary color signals R1G and B described in "1"
has the same band as the above color difference signal Y, and has 3 plates or 3
Suitable for tube color imaging devices. In Clay 1.3, the three primary color signals R, G, and B have smaller bands than the color difference signal Y, and are suitable for a single-panel or medium-tube color imaging device.

The luminance reproducibility of the gun/correction method of the present invention will be explained below.

Assuming that the input color video signals are R, G, and B, and subjecting them to gamma correction, R'= R'L -I R'H G"-G'L-LG'H T3' == B' L 1 B' I-1+Konaru.

When the above gamma-corrected color signal is gamma-converted again, the input video signal is completely converted to Reproduced.

In the conventional three primary color gamma correction method, R'R'L
斗1Y:l-1G゛・G'L TO iYl'T-
1R'-H' L +lY:' I-1□Y:
° I-] = o 3 rt' H-
0 59G 'H-10,11B'
Become H.

When the above gamma-corrected color signal is gamma-converted again,
r G = (G'L @ iY :l-1)゛, (G'l
, )'+2.20'L x IY :°11 L (
1'l:'old', (j)B=(13・1.-□,y
j・１□) Become.

In the gamma correction method of the present invention, R'R'L + (Y)'H c'c'+,i(Y')'IIB'T3°L −+ (Y)' II(Y )' T
-1 (0,3R-Io, 59G to 0.11B)'Hj Konaro.

When the above gamma-corrected color signal is gamma-converted again, it becomes 1, f. yt (R"L-1(Y)'H) B-(“3°L→(”i’)Ml) -I Rensho IZl Tower.

The above equations (1), (2), (3) and (4), (5), (
6) Comparing the equations, the first term of the old equation is equal to 1. <, and 1f in which the second and third terms are different can be found. Generally speaking, the second and third terms in each equation are the high-frequency components (Y)H of the reproduced color difference signal, so by multiplying by the visual sensitivity, from equations (1), (2), and (3), ( Y) H-2,2(0,3R' 1.x Ishi゛11 to 0.59G'l, XG'1liO, Il+(°l,
°11), -5'', ?5' +0.3(
RH) -tO,59(G11)→0. II(1'
Become l'l+).

Similarly, from ('I), (5), (6), (Y)
II-Mi 2.2 (0,3R' L + 0.59G'
I, = 1-0.11B°l,) x lv M I
It becomes I + (IY, 'II).

The above equations (+), (2), (3) and (7), (8),
Comparing equations (9'), we can see that the first term of equation 6 is the same, and whether the second and third terms are different.
I can understand 1 construction. Therefore, the high-frequency component (Y) I-1 of the visually corrected reproduced color difference signal is obtained from equations (7), (8), and (9') as follows: (Y)It'; 2.2(0,3R 'L'0.59G
'L〇,III3'l,)x(y)'n-1((Y)
'II) becomes 11''.

In the gamma correction method of the present invention, reproduction of three primary colors, F
, the low-frequency components (prospective) of r are (RL) , (G L
).

. 6)). Then, the high frequency component (
Y)H is (Y)I- of the above three primary color gamma correction method
1 is closer to (Y)H of the complete gamma correction method. Human video signal R-RI, 1R11-G:GI, 10G[1-
-B--BL-IB [・Record ζh 3 types of Kanoma Hoichi system high-frequency component (Y') of the current color difference signal II U,"!
F L.

RL = GL = RL = YL, YlI O, 3RII
Or, under the 0.59GT-1 or 0.111111-ζDuro high-range primary color conditions, the first term of present invention (1) (, Y) II is larger than that of the complete gamma correction method, but the second term is Complete gamma correction method) And (Y)I of the three primary color gamma correction method
The first and second terms of I are smaller than the first and second terms of the complete gamma correction method, respectively.

Y 0.3(RL, )RH), or Y・-0,59
(G1, l CII'), or Y-0, I I (
Under the human power condition where BL + BH), the first term of (Y)T-1 of the present invention is a complete gamma extraction IT
(Slightly smaller than that of the three-primary gamma correction method, and its second term is equal to the second term of the full gamma correction method.
Y) The first and second terms of IT are significantly smaller than the first and second terms of the complete gamma correction method.

From the above results, it can be seen that the conventional three primary color gamma correction method is false when the spectral spectrum when the high frequency component YI-1 of the human color difference signal is not white is different from the spectral spectrum of the Y11 component. Y) Is the first term of 11) occurring at 4?

The above attenuation is small c1! I know it's JT.

In the deck or middle tube color imaging device, the low frequency components of the three primary colors L, GL, BI, and A are
RL', GL', and B synthesized using gamma complementary IL
Lo is the above R' L, G' L, , B'
Since it is roughly the same as 31. I, only the gamma correction circuit for the color difference signal Y is wideband, and the gamma correction circuit for the three primary color signals is narrowband. So, put the circuit inside the cylinder.

In addition, the high frequency component Y'H of the output color difference signal Yl is expressed as (Y
)”H, and the low frequency component RL of the above three primary color signals
, GL, BL and the high frequency component YIT of the color difference signal to obtain the color signal Rx=RL+-Yl(,Gx=GL
(Y) Synthesize 1,11X RT, 1Y H, and 2 the above Uoshin SE, Rx.

(Gamma correction is performed on J
Synthesize Uoshin 1-+, R
From G X', B There are four embodiments in which Invention 1 and Invention 2 are used together.

This embodiment is particularly suitable for extracting high-frequency components of the three primary color signals.
It is difficult to reduce false signals in single-plate or tP-tube color imaging devices.

German invention 2. Clay 1.4 - The gamma correction method of Independent Invention 1 above has better high-range luminance reproducibility than the three primary color gamma extraction method, but there is still room for improvement. In order to solve this problem, the present invention aims to extract high-frequency components YH of color difference signals and low-frequency components of three primary color signals (narrowband three primary color signals) from the output quality of the imaging device R1, , C1,
,, r3 L, and from each of the above signals, the color signal Rx=-RL-+YLl, G
, Bx-BL 1 Y I-1, and 1]
Gamma-correct the synthetic fish signal "r numbers Rx, G x, By, respectively, and synthesize Rx', Gx', 13x', and then synthesize the gamma-corrected fish signal ';Rx', G X'
, Bx' to output color difference signal Y'=0.3rjx'
-g 0. 59Gx')0. I I
B x' and two types of output color difference signals C
It is characterized by synthesizing I' and 02'. In general, -
The above output color difference signals are (Rx"-Y'), (B X'
-Y') or (It
+' synthesized from -T3 x)' and (Rx'-Y')
, Q' are low frequency components.

This invention is! - In the three primary color gamma correction force equations described above, the high frequency components RII, CI-1, B of the human input signals R, G, and R are
T-1 is the high frequency component of the human color difference signal Y T-T = R
It is possible to output an output color difference signal Y° when 'H=GIT-=B1-1 (white) and two types of output color difference signals Cbi and 02'. Under the above conditions, the three primary color gamma correction method hardly generates false signals.

Therefore, by the gamma correction method of the present invention, the three low-range primary color signals RL, GL, BL and the high-range color difference signal YT-
1 will be almost completely regenerated and the false signals will be very low.

An advantage of the invention is that the color signals Rx, Gx are gamma corrected.

B 11 is an improvement over the gamma correction method.Another advantage of the present invention is that the gamma correction circuit uses a 3-channel wideband gamma correction circuit instead of a 4-channel gamma correction circuit. The circuit is simpler than that.

In one embodiment of the present invention having the best reproducibility, as stated above in claim 5, the high-frequency component Y'I-1 of the color difference signal Y' for output horns is the same as (Y)'II of Independent Invention 1. Be it. As a result, since the false signals of the independent holes nj1l are almost eliminated, the high frequency components of the reproduced color difference signal Y have extremely high fidelity.

Other features and effects of the present invention will be explained in the following embodiments.BEST MODE FOR CARRYING OUT THE INVENTION FIG. 1 is a block circuit diagram showing an embodiment of independent invention 1. Output signals Sl and S2 of two adjacent pixel rows are output from the single-plate color solid-state image sensor 1, and Sl and S2 are converted into a color difference signal Y and three primary color signals R1G and B by a signal synthesis circuit 2.

Generally, the color difference signal Y is synthesized by the sum of output signals of two adjacent pixel rows, and the R, G, and B signals are separated by extracting each pixel signal or the difference thereof. Since these signal separation methods are well known, their explanation will be omitted.3 The color difference signal Y and R, G, B signals output from the signal synthesis circuit 3 are passed through low-pass filters (LPFs) 3a, 3b, 3c, respectively. Bandwidth is limited in 3D. L P F 3 a is about 3.5 MI (
The other LPFs 4b, 4c, and 4d have a band of about I
Has a band of M1-Tz-) JLPF4b, 4c, 4
It is preferable to output color signals R, G, and B in as wide a band as possible in the band d.

Signals Y, RL, GL output from each LPF
, BL are gamma correction circuits 4 a, 4 b, 4, respectively.
c, /I Do gamma correction with d. The gamma-corrected color difference signal (Y) output from 4a is passed through a bandpass filter (BP
F) 6a, and the high frequency component of the output color difference signal Y° becomes Y'I-1=(Y)'11. Gamma correction color signals (Rr, )', (c1.), (B
10) ° is the signal synthesis circuit 5, gamma correction color difference signal IY
i'= 0 3CR1,Y(0,59(GL)'+0
．． 11(RL)' and gamma-corrected color difference signal 01°-(T
(L)'-IYI° and gamma-compensated iE color difference signal C2° = (
BL)'-IY l".The gamma-corrected color difference signal IYB and the color difference signals C1° and C2° each have a band of about 0.5 MIIz, and are converted into LPFs 6b, 6c,
6d, and the low frequency components Y'L-lYloL of the output color difference signal Y°, and the output color difference signal C1°L, C
It becomes 2°17. And output color difference signal Y'=Y'l,
10Y'II = IY l'l, -+(Y)'H.

FIG. 2 is a block circuit diagram of an embodiment of the German σ invention 2. FIG. 2 is basically the same as FIG. 1. However, the color difference signal Y output from the signal synthesis circuit 2 is approximately 0.5MT-1z
A bandpass filter (BPF) with a band of 3.5MT (z)
)3e, and its high frequency component YH is extracted. And then, P F 3 b, 3 C, 3 (l is about 0.5 M H
It has a band of z. Then, the gamma correction circuit 4b outputs the color signal R.
The gamma correction circuit 4C performs gamma correction on the color signal Gx=GL→YH, and the gamma correction circuit 4 (I is the color signal BX=BL
±YH is gamma corrected. Gamma correction color signal R
x', G
x'→0, l I By,' and output color difference signal C
1°=Rx'-Y', C2'-Bx'-Y'. 1. P P6 limits the band of the output color difference signal Y' of I- to below about 35 M I-1z, and LPF6
c, 6d limit the band of the above output color difference signals CI', C2° to approximately 0.5 MI (z or less).

FIG. 3 is a block circuit diagram of an embodiment of the present invention using Independent Invention 1 and Independent Invention 2 together. Figure 3 is basically Figure 2
is the same as However, the difference from FIG. 2 is that the output color difference signal Y' output from the signal synthesis circuit 5 is approximately 0.5 MH
1 with a band of z. The band is limited by P F'6b, and the low frequency component Y'1. of the output color difference signal Y° is band-limited. It is to become. Then, the color difference signal Y output from the signal synthesis circuit 2
As in FIG. 1, the signal is band-limited by L P F 3 a having a band of approximately 3.5 MIIz, and then gamma-corrected by the gamma correction circuit 4a to produce a gamma-corrected color difference signal (Y
)°, and the above gamma-corrected color difference signal (Y)°
is a BP with a band of about 0.5 MHz to about 3.5 MHz.
The band is limited by P6a and becomes the high frequency component Y'H of the output color difference signal Y'. Of course, the output color difference signal is finally Y'=Y'l, DoY'H" (0, 3Rx'-
40, 59Gx'10, I I Bx')L+(
Y)'Hl Konaru.

Note that each of the embodiments listed below describes a signal processing circuit for an NTSC type TV camera using a single-plate color solid-state image pickup device, but it goes without saying that the present invention can also be used in other image pickup devices.

[Brief explanation of drawings]

Claims (7)

[Claims] (1) Separate or combine the luminance signal Y and the three primary color signals R, G, and B from the output signal of the imaging device, and perform gamma correction on each of the above signals Y, R, G, and B to generate a gamma-corrected signal ( Y)', R', G', and B' are synthesized, and from the above gamma correction signals (Y)', R', G', and B', an output luminance signal Y' and two types of output color difference signals are obtained. C1', C2'
In the signal processing circuit of the imaging device, the gamma-corrected luminance signal |Y|' is synthesized from the gamma-corrected color signals R', G', and B', and the gamma-corrected luminance signal |Y|' By adding the low frequency component |Y|'L and the high frequency component (Y)'H of the above gamma-corrected luminance signal (Y)', the output luminance signal Y'=|Y|'L+(Y)'H is obtained. A signal processing circuit for an imaging device characterized by combining. (2) The signal processing circuit for an imaging device according to item 1, wherein the signals Y, R, G, and B separated or combined from the output signal of the imaging device have approximately equal bands. (3) Item 1, wherein the luminance signal Y separated or combined from the output signal of the imaging device has a wider band than the three primary color signals R, G, and B, which are similarly separated or combined. A signal processing circuit of the imaging device described. (4) In a signal processing circuit of an imaging device that synthesizes a gamma-corrected output luminance signal Y' and two types of gamma-corrected output color difference signals C1' and C2' from an output signal of the imaging device, the imaging device The three color signals Rx, Gx, Bx are separated or combined from the output signals of the three color signals Rx, Gx, B.
x is the high frequency component YH of the luminance signal Y and the three primary color signals R, G, B
Addition signal of each low frequency component RL, GL, BL (Rx=RL
+YH, Gx=GL+YH, Bx=BL+YH), and the above three color signals Rx, Gx, and Bx are gamma-corrected to produce gamma-corrected color signals Rx', Gx', and Bx'
and the above gamma-corrected color signals Rx', Gx
', Bx', at least the low frequency component Y'L of the output luminance signal Y' is synthesized, and the high frequency component (Y
)'H or the above gamma-corrected color signal Rx'
Gamma-corrected luminance signal synthesized from , Gx', and Bx' |
Yx|'(=0.3Rx'+0.59Gx'=0.11
Bx') high-frequency component |Yx|'H, or by mixing the above (Y)'H and |Yx|'H at an appropriate ratio, the low-frequency component Y' of the output luminance signal Y' A signal processing circuit for an imaging device characterized by combining L. (5) Separate or combine the broadband luminance signal Y of the imaging device, gamma-correct the luminance signal Y, synthesize the gamma-corrected luminance signal (Y)', and synthesize the gamma-corrected luminance signal (Y)'. 5. The signal processing circuit for an imaging device according to claim 4, wherein the high frequency component (Y)'H of )' is the high frequency component Y'H of the output luminance signal Y'. (6), the above gamma-corrected color signals Rx', Gx', Bx
5. The signal processing circuit for an imaging apparatus according to claim 4, wherein the signal processing circuit synthesizes both the low frequency component Y'L and the high frequency component Y'H of the output luminance signal Y' from '. (7) Separating or combining the above three color signals Rx, Gx, Bx from the output signal of the single-plate or single-tube color imaging device;
7. The signal processing circuit for an imaging device according to claim 6, wherein the low frequency component of the output signal of the imaging device is approximately a luminance signal Y.