JPH03211977A - Color image pickup device - Google Patents

Abstract

PURPOSE:To improve resolution in a horizontal direction without increasing the number of picture elements in a solid-state image pickup element and the number of soil-state image pickup elements by obtaining a luminance signal by alternately adding the image pickup signal of three continuous fields from the solid-state image pickup element at a 1/2 picture element cycle. CONSTITUTION:A solid-state image pickup element 4 is provided with the color filter of a complementary check system, and picture element shifting mechanisms 3 and 5 are provided to successively shift the positions of pictures, which are picked up at the picture element part related to the same color of the solid-state image pickup element 4, only for a 1/2 picture element pitch in the horizontal direction for each field. Then, a time control means 6 is provided to make the timing of the image pickup signal in the horizontal direction of each field to be outputted from the solid-state image pickup element 4 corresponding to the amount of shifting by the picture element shifting mechanisms. Further, a signal processing means 14 is provided to obtain the luminance signal by alternately adding the image pickup signals of one field and the other two fields at the 1/2 picture element cycle out of the image pickup signals of the three continuous field from the solid-state image pickup element 4 which the horizontal direction timing controlled by the time control means 6. Thus, the resolution in the horizontal direction is improved without increasing the number of the picture elements in the solid-state image pickup element 4 and the number of solid-state image pickup elements.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a color imaging device configured using a solid-state imaging device having a complementary color checkerboard color filter.

[Prior Art] Conventionally, methods for performing high-resolution imaging in a color imaging device configured using, for example, a CCD solid-state image sensor include a method using a multi-pixel solid-state image sensor, and a solid-state image sensor using two or more plates. Methods of configuring using elements have been proposed.

[Problems to be Solved by the Invention] However, the method of using a multi-pixel solid-state image sensor has the disadvantages of being expensive and bulky. Also,
It is necessary to perform driving and signal processing at high speed, making the configuration difficult.

Further, according to the method of using two or more solid-state image sensors, the optical system becomes complicated, expensive, and large in size.

SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide a color imaging device that can perform high-resolution imaging without causing the above-mentioned inconveniences.

Means for Solving Lesson 0 M] This invention uses a solid-state image sensor having a complementary color checkerboard color filter, and a field that determines the position of an image imaged by a pixel portion of the same color of the solid-state image sensor. to 1/2
A pixel shift mechanism that sequentially shifts the pixel pitch, a time adjustment means that makes the horizontal timing of the image signal of each field output from the solid-state image sensor correspond to the amount of shift by the pixel shift mechanism, and a time adjustment means that sequentially shifts the pixel pitch. Among the three consecutive fields of imaging signals from the solid-state imaging device whose horizontal timing has been adjusted, the imaging signals of the 1/2 pixel circumference and the other two fields are added alternately to generate a luminance signal. and a signal processing means for obtaining.

[Function] In the above configuration, the signal processing means 14() outputs the luminance signal Y using 1/2 pixel 1!1111f of the image pickup signal. In other words, it is possible to increase the resolution in the horizontal direction without increasing the number of pixels of the solid-state image sensor 4 or without increasing the number of solid-state image sensors 4.

[Embodiment] An embodiment of the present invention will be described below with reference to FIG.

In the figure, image light from a subject (not shown) is passed through an imaging lens 1, an iris 2, and an optical path changing unit 3 constituting a pixel shifting mechanism to a CCD solid-state image sensor 4 having a complementary color checkerboard color filter. Supplied.

FIG. 2 is a schematic color coding diagram of this image sensor 4. As shown in FIG. As shown in the figure, field reading is performed. In the A field, charges are mixed in pairs such as AI and A2, and in the B field, charges are mixed in bare pairs such as B1, and then read out.
be done.

Therefore, the order of charges output from the horizontal shift register Hre,g is (c+c
y), (Ye +Mg), (c+c,),
(Ye+M8), ..., and on the A2 line, (Cy +Mg), (Ye
+G), (Cy +Mg), (Ye
+G), ... howl.

In order to process this imaging signal and obtain a luminance signal Y and a chroma (color difference) signal, the luminance signal Y must be summed with adjacent comrades,
The chroma signal is subtracted.

In other words, the luminance signal Y is A1 line' ” Y = ((G+CV)+(Ye+M
g)>X l/2=(2B+3G+2R) X 1/2 A2 line' ・Y=C(Cy+Mg)+(G+Ye
)) X 1/2=(2B+3G+2R) X 1/2 (1) It is approximated as follows. Here, C = B + G, Ye - = R + G
, Mg=F3+R.

In addition, the chroma signal is A1 line-R-Y=((Ye+Mg)-(G+Cy
))”(2R-Gn A2 line...-(B-V)=((G+Ye)-(Mg
+Cy):=-(2B-G) ・ ・ ・ (2) It is approximated as follows. In other words, the chroma signal is R-Y.

(B-Y) are taken out alternately in line sequence.

In addition, in FIG. 2, Px indicates one pixel pitch.

The operation of the optical path changing section 3 is controlled by the controller 5, so that the field, particularly the image position taken by the TJ1 element 4, is sequentially shifted. In other words, as shown in FIG. 3, the first to fourth fields are sequentially shifted by 1/2 pixel pitch Px/2 in the horizontal direction, and the following fields are shifted sequentially by 1/2 pixel pitch Px/2.
In the 8th field, 9th to 12th fields, . . . , the shift is made in the same way as in the 1st to 4th fields.

In this case, the same color of the image sensor 4 (for example, (G+Cy)
The position of the image captured by the pixel part of one system in the part) is sequentially shifted by ]/2 pixel pitch in the horizontal direction for each field.

6 is a timing generator. This timing generator 6
The operation of the controller 5 is controlled by the controller 5, and the horizontal opening 1 is sent to the controller 5 from the timing generator 6.
[jl signal HD and vertical synchronization signal VD are supplied.

Timing pulses necessary for the image sensor 3 are supplied from a timing generator 6, and the image sensor 3 operates in the same manner as a conventionally known one, except for the following output timing in the horizontal direction.

In other words, the timing in the horizontal direction of the imaging signal of each field output from the imaging device 3 is sequentially adjusted in accordance with the shift amount of the image position captured by the imaging device 4. As shown in FIG. 4, if the output timing of the first field is used as a reference, in the second field, the 1/2 pixel dark period T\
/is delayed by 1 pixel period Tx in the third field.
3/2 pixel rotation in the 4th field
The timing is delayed by 3 T x /2, and the timing for the fifth to eighth fields, the ninth to twelfth fields, . . . is the same as that for the fourth field.

Note that FIG. 4 shows the imaging signals of 11 lines of each field, and an and b n (n: 1.2.3.
) are respectively placed in the nth field (G+C~
) and (Ye-+-Mg) pixel 1 word is shown.

An image signal from the image sensor 4 is supplied to a clamp circuit 8 via an AGC amplifier 7.

Note that the imaging signal from the imaging device 4 is supplied to the Leher detector 9, and the detection signal is supplied as a control signal to the iris driver 10, and the opening of the iris 2 is controlled by the iris driver 10. Also, AGC amplifier 7
The output signal is supplied to the level detector 11, and the detection signal is supplied to the AGC amplifier 7 as a control signal via the amplifier 12. 7a is a potentiometer for setting the maximum gain of the AGC amplifier 9.

A clamp pulse is supplied from the timing generator 6 to the clamp circuit 8, and the clamp pulse is clamped during the horizontal blanking period so that the black level is constant and becomes healthy.

Shooting tI output from the clamp circuit 8! The signal is A/D
After being converted into a digital signal by a converter 13, the signal is supplied to a digital processing circuit 14. The A/D converter 13 samples each pixel signal so that the horizontal output timing shift of the image signals of each field applied to the image sensor 4 is maintained.

FIG. 5 shows the configuration of the digital processing circuit 14.

In the same figure, the image signal supplied from the A/D converter 13 is transmitted to the field memory 31 and the changeover switches 32 and 33.
A luminance signal processing unit 3 configured with an adder 34 and an adder 34
0.

Writing and reading of the field memory 31 and switching of the changeover switches 32 and 33 are controlled by the controller 5. That is, the changeover switches 32 and 33 control the synchronization (
The first half of the pixel period is connected to the H side, and the second half is connected to the L side.
connected to the side. Further, the output signal of the changeover switch 32 is written into the field memory 31 with a period of 172 pixels, and is read out with a period of 1/2 pixel after one field F'ItM. Roughly speaking, in the adder 34, each signal is added with a coefficient of 1/2.

The luminance signal processing unit 30 is configured in this way, and in the third field, the first and second
A pixel signal constituting a luminance signal Y obtained by adding and averaging the pixel signals of the field is output, and in the latter half of the period, a luminance signal Y obtained by adding and averaging the pixel signals of the second and third fields is output.
The pixel signals constituting the pixel signal are output (shown in FIG. 4 with the addition pairs connected by solid lines). In other words, the changeover switch 33 outputs a luminance signal Y that is formed using the first to third field imaging signals and has a pixel period that is 1/2 of the pixel period of the imaging signal.

In addition, in the fourth field, a pixel signal constituting the luminance signal Y obtained by adding and averaging the pixel signals of the second and third fields is output in the first half of the pixel period, and in the second half of the pixel period, the pixel signals forming the luminance signal A pixel signal constituting a luminance signal Y obtained by adding and averaging the pixel signals of is output (the addition bears are shown connected by a broken line in FIG. 4). In other words, from the changeover switch 33, the shooting 1ff of the second to fourth fields is
The luminance signal Y is formed with the number i1N and has a pixel period that is 1/2 of the pixel period of the image pickup signal.

Furthermore, in the fifth field, a pixel signal constituting the luminance signal Y obtained by adding and averaging the pixel signals of the third and fourth fields is output in the first half of the pixel cycle, and the pixel signals of the fourth and fifth fields are output in the second half of the pixel period. A pixel signal constituting a luminance signal Y obtained by adding and averaging the pixel signals of is output (the addition bears are shown connected by a dashed-dotted line in FIG. 4). In other words,
From the changeover switch 33, it is formed with the image pickup signal of the 3rd to 5th field, and 1 for the pixel period of the image pickup signal.
A luminance signal Y having a pixel period of /2 is output.

Similarly, in each field, the changeover switch 33
, outputs a luminance signal Y which is formed from three fields of imaging signals including the current field and has a pixel period of 1/2 with respect to the pixel period of the imaging signal.

FIG. 6 shows the A/D converter 1 in the first to fifth fields.
3 output, field memory 310 output, adder 34
The output of the changeover switch 33, the output of the changeover switch 32.
33 shows the switching relationship. To simplify the drawing, the 1/2 coefficient in the adder 34 is not shown.

Further, in FIG. 5, the imaging signal supplied from the A/D converter 13 is supplied to a chroma signal processing section 40. This chroma signal processing unit 40 performs the subtraction process of equation (2) described above, and the color difference signal R-Y, -(B-Y) having a pixel period twice that of the image signal is &! Output in sequence.

Returning to FIG. 1, the luminance signal Y output from the digital processing circuit 14 is converted into an analog signal by D/A conversion @ 15, and then processed by the gamma correction circuit 16 and the gain amplifier 1.
7 to an encoder 18. The color difference signal output from the digital processing circuit 14 is sent to the D/A converter 19.
The signal is converted into an analog signal and then supplied to the encoder.

In the encoder 1, processing such as addition of the same gate signal to the luminance signal Y and modulation of the color difference signal is performed to form, for example, a video signal SV of the NTSC system. This video signal SV is then led out to the output terminal 20.

In this example, the pixel period of the luminance signal Y output from the digital processing circuit 14 is 172 of the pixel period of the image signal from the image sensor 4, and a high-resolution video signal S can be obtained. .

According to this example, since it does not use a multi-pixel solid-state image sensor, it does not have the disadvantage of being expensive and large, and it does not require high-speed driving and signal processing, so the configuration may be difficult. do not have. In addition, two solid-state image sensors
Since no more than a plate is used, there is no problem that the optical system becomes complicated, expensive, and large.

In the above-mentioned embodiment, the video signal S for moving pictures is output, but the digital processing circuit 14 repeatedly outputs a video signal for one screen formed of three arbitrary fields. By doing this, it is also possible to obtain a video tllN number for still images. In this case, it is necessary to hold the luminance signal Y for one screen formed by three fields in a memory, and a similar memory is also required for the color difference signal system.

Further, in the above embodiment, the pixel shifting mechanism includes the optical path changing unit 3, but the optical path may be kept constant and the position of the image sensor 4 may be moved.

Further, in the above embodiment, it has been explained that the horizontal output timing shift of the image pickup signal of each field is applied by the image pickup element 4, but after the output from the image pickup element 4, the luminance signal processing of the digital processing circuit 14 is performed. It may be applied before being supplied to the section 30.

Furthermore, in the above embodiment, as the solid-state image sensor, C
Although an example is shown in which a CD solid-state image sensor 4 is used, the present invention can be similarly applied to obtain a high-resolution video signal when using a solid-state image sensor having a complementary color checkered color filter. Be able to do that.

[Effects of the Invention] As explained above, according to the present invention, horizontal resolution can be improved by pixel shifting and signal processing without increasing the number of pixels of a solid-state image sensor or without increasing the number of solid-state image sensors. It is possible to perform high-resolution imaging without inconveniences such as high cost, large size, and difficulty in configuration.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a color coding schematic diagram, Fig. 3 is an explanatory diagram of pixel arrangement, Fig. 4 is an explanatory diagram of luminance signal processing, and Fig. 5 is an explanatory diagram of luminance signal processing. A specific configuration diagram of the digital processing circuit, FIG. 6 is an explanatory diagram of the operation of the luminance signal processing section. 3... Optical path changing unit 4... CCD solid-state image sensor 5, 6, 4-30, 40, controller, timing generator, digital processing circuit, luminance signal processing unit, chroma signal processing unit

Claims (1)

[Claims] (1) A solid-state image sensor having a complementary color checkerboard color filter, and the position of images captured by pixel portions of the same color of the solid-state image sensor are sequentially shifted by 1/2 pixel pitch in the horizontal direction as a field. a pixel shifting mechanism; a time adjustment means for making the horizontal timing of the imaging signal of each field outputted from the solid-state imaging device correspond to the shift amount by the pixel shifting mechanism; and adjustment of the horizontal timing by the time adjustment means. and a signal processing means for obtaining a luminance signal by alternately adding the imaging signals of one field and the other two fields at a 1/2 pixel period among the three consecutive fields of imaging signals from the solid-state imaging device. Color imaging device.