JP2693845B2 - Color imaging device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a color image pickup apparatus including a solid-state image pickup element having a complementary color checkered color filter.

[Prior Art] Conventionally, in a color image pickup apparatus including a CCD solid-state image pickup device, as a method of performing high-resolution image pickup, a method including a multipixel solid-state image pickup device is used. A method and the like of using an element have been proposed.

[Problems to be Solved by the Invention] However, a method using a solid-state imaging device having a large number of pixels has a disadvantage that the cost is high and the size is large. Also,
It is necessary to perform driving and signal processing at high speed, which makes the configuration difficult.

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

Therefore, it is an object of the present invention to provide a color image pickup device capable of performing high-resolution image pickup without causing the above-mentioned inconvenience.

[Means for Solving the Problems] According to the present invention, a solid-state image pickup device having a complementary color checker system color filter and an image position picked up by a pixel portion of the same color of the solid-state image pickup device are set horizontally in each field. With a pixel shift mechanism that sequentially shifts by / 2 pixel pitch, a time adjustment unit that makes the horizontal timing of the image pickup signal of each field output from the solid-state image sensor correspond to the shift amount by the pixel shift mechanism, and a time adjustment unit. A signal that obtains a luminance signal by alternately adding the image signals of one and the other two fields in a 1/2 pixel cycle among the image signals of three consecutive fields from the solid-state image sensor whose horizontal timing is adjusted. And a processing means.

[Operation] In the above-described configuration, the signal processing unit 14 outputs the image pickup signal.
The luminance signal Y is output with a 1/2 pixel period. That is, it is possible to increase the resolution in the horizontal direction without increasing the number of pixels of the fixed image pickup element 4 and without increasing the number of solid state image pickup elements 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 which constitutes a pixel shifting mechanism to a CCD solid-state image sensor 4 having a complementary color checkered color filter. Supplied.

FIG. 2 is a schematic diagram of color coding of the image pickup device 4. As shown in the figure, field reading is performed. In the A field, charges are mixed in pairs such as A1 and A2, and in the B field, charges are mixed in pairs such as B1 and then reading is performed. Therefore, the order of charges output from the horizontal shift register Hreg is (G + C
y), (Ye + Mg), (G + Cy), (Ye + Mg), ... And in the A2 line, (Cy + Mg), (Ye + G),
(Cy + Mg), (Ye + G), ...

Normally, in order to obtain the luminance signal Y and the chroma (color difference) signal by processing the image pickup signal, the luminance signal Y is obtained by adding the adjacent signals and the chroma signal is subtracted.

That is, the luminance signal Y is A1 line ... Y = {(G + Cy) + (Ye + Mg)} × 1/2 =
(2B + 3G + 2R) × 1/2 A2 line ... Y = {(Cy + Mg) + (G + Ye)} × 1/2 =
(2B + 3G + 2R) × 1/2 …… (1) is approximated. Here, Gy = B + G, Ye = R + G, Mg = B +
R.

Also, the chroma signal is A1 line ... RY = {(Ye + Mg)-(G + Cy)} =
(2R-G) A2 line ... (B-Y) = {(G + Ye)-(Mg + Cy)}
=-(2B-G) ... (2) is approximated. In other words, the chroma signal is RY,-(B-
Y) are taken out line by line alternately.

Note that, in FIG. 2, Px represents one pixel pitch.

The operation of the optical path changing unit 3 is controlled by the controller 5 so that the image positions captured by the image sensor 4 are sequentially shifted for each field. That is, as shown in FIG. 3, the first to fourth fields are sequentially shifted in the horizontal direction by 1/2 pixel pitch Px / 2, and the fifth to eighth fields, the ninth to twelfth fields, .. are shifted like the first to fourth fields. in this case,
The image positions picked up by the pixel portions of the same color (for example, the (G + Cy) portion) of the image sensor 4 are sequentially shifted in the horizontal direction by 1/2 pixel pitch for each field.

6 is a timing generator. The operation of the timing generator 6 is controlled by the controller 5 and
A horizontal synchronizing signal HD and a vertical synchronizing signal VD are supplied from the timing generator 6 to the controller 5.

The timing pulse required by the image pickup device 3 is supplied from the timing generator 6, and the image pickup device 3 operates in the same manner as the conventionally known one except the horizontal output timing described below.

That is, the horizontal timing of the image pickup signal of each field output from the image pickup device 3 is sequentially adjusted in accordance with the shift amount of the image position picked up by the image pickup device 4. As shown in FIG. 4, with reference to the output timing of the first field, the second field is delayed by 1/2 pixel period Tx / 2, and the third field is delayed by 1 pixel period Tx. Is delayed by 3/2 pixel period 3Tx / 2, and the same timings are used in the fifth to eighth fields, the ninth to twelfth fields, ...

Note that FIG. 4 shows the image pickup signal of the first line of each field, and an and bn (n = 1, 2, 3, ...)
Indicate pixel signals of (G + Cy) and (Ye + Mg) in the nth field, respectively.

The image pickup signal from the image pickup device 4 is supplied to the clamp circuit 8 via the AGC amplifier 7.

The image pickup signal from the image pickup device 4 is supplied to the level detector 9, and the detection signal is supplied to the iris driver 10 as a control signal, and the iris driver 10 controls the opening of the iris 2. The output signal of the AGC amplifier 7 is supplied to the level detector 11, and the detection signal is supplied to the AGC amplifier 7 via the amplifier 12 as a control signal. 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 is clamped in the horizontal blanking period so that the black level becomes a constant level.

The image pickup signal output from the clamp circuit 8 is converted into a digital signal by the A / D converter 13 and then supplied to the digital processing circuit 14. In the A / D converter 13, each pixel signal is sampled so that the deviation of the horizontal output timing of the image pickup signal of each field given by the image pickup device 4 is maintained.

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

In the figure, the image pickup signal supplied from the A / D converter 13 is supplied to a luminance signal processing unit 30 including a field memory 31, changeover switches 32 and 33, and an adder 34.

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 are connected to the H side in the first half period of the cycle (pixel cycle) of each pixel signal forming the image pickup signal from the A / D converter 13, and are connected to the L side in the second half period. Further, the output signal of the changeover switch 32 is written in the field memory 31 at a 1/2 pixel cycle, and is read out at a 1/2 pixel cycle after one field period. Further, in the adder 34, the respective signals are added with a coefficient of 1/2.

The luminance signal processing unit 30 is configured as described above, and in the third field, the first and second pixels are provided in the first half period of the pixel cycle.
Pixel signals forming a luminance signal Y obtained by adding and averaging the pixel signals of the fields are output, and luminance signals Y obtained by adding and averaging the pixel signals of the second and third fields in the latter half period.
Is output (the addition pair is shown as a solid line in FIG. 4). That is, the changeover switch 33 outputs the luminance signal Y which is formed by the image pickup signals of the first to third fields and has a pixel period of 1/2 of the pixel period of the image pickup signal.

In the fourth field, a pixel signal forming the luminance signal Y obtained by adding and averaging the pixel signals of the second and third fields is output in the first half period of the pixel period, and in the latter half period of the third and fourth fields. A pixel signal forming a luminance signal Y obtained by adding and averaging the pixel signals of is output (the addition pair is shown by a broken line in FIG. 4). That is,
From the changeover switch 33, it is formed with the image pickup signals of the second to fourth fields, and is 1/2 of the pixel period of the image pickup signal.
The luminance signal Y having the pixel period of is output.

In the fifth field, a pixel signal forming the luminance signal Y obtained by adding and averaging the pixel signals of the third and fourth fields is output in the first half period of the pixel cycle, and in the latter half period of the fourth and fifth fields. A pixel signal that constitutes the luminance signal Y obtained by adding and averaging the pixel signals of is output (the addition pair is shown in FIG. 4 by connecting with a dashed line). In other words, the changeover switch 33 forms the image signals of the third to fifth fields, and
A luminance signal Y having a pixel period of 1/2 is output.

Similarly, in each field, changeover switch 33
From, a luminance signal Y which is formed with image pickup signals of three fields including the current field and has a pixel period of ½ of the pixel period of the image pickup signal is output.

FIG. 6 shows the A / D converter 13 in the first to fifth fields.
, The input / output of the field memory 31, the output of the adder 34, the output of the changeover switch 33, and the changeover of the changeover switches 32, 33 are shown. Adder for simplicity of drawing
Illustration of the 1/2 coefficient in 34 is omitted.

Further, in FIG. 5, the image pickup signal supplied from the A / D converter 13 is supplied to the chroma signal processing unit 40. In the chroma signal processing unit 40, the subtraction processing of the above-described equation (2) is performed, and the color difference signals R−Y, − (B−Y) having a pixel period twice the pixel period of the image pickup signal are line-sequential. Is output with.

Returning to FIG. 1, the luminance signal Y output from the digital processing circuit 14 is converted into an analog signal by the D / A converter 15, and then supplied to the encoder 18 via the gamma correction circuit 16 and the gain amplifier 17. It The color difference signal output from the digital processing circuit 14 is converted into an analog signal by the D / A converter 19 and then supplied to the encoder 18.

The encoder 18 performs processing such as addition of a sync signal to the luminance signal Y and modulation of a color difference signal to form an NTSC video signal SV, for example. Then, the video signal SV is led to the output terminal 20.

As described above, in the present example, the pixel cycle of the luminance signal Y output from the digital processing circuit 14 is half the pixel cycle of the image pickup signal from the image pickup device 4, and the high resolution video signal SV can be obtained. it can.

According to this example, since a solid-state image pickup device having a large number of pixels is not used, there is no inconvenience of being expensive and upsizing, and the configuration is difficult because it is not necessary to perform driving and signal processing at high speed. Absent. Further, since the solid-state image pickup element is not used for two or more plates, there is no inconvenience that the optical system is complicated and expensive and large.

In the above embodiment, the video signal SV for the moving image is output, but the digital processing circuit 14 repeatedly outputs the video signal for one screen formed in any three fields. With this, it is possible to obtain a video signal for a still image. In this case, it is necessary to hold the luminance signal Y for one screen formed by 3 fields in the memory, and the same memory is required for the color difference signal system.

Further, in the above-described embodiment, the one in which the optical path changing unit 3 is provided as the pixel shifting mechanism has been described, but the optical path may be fixed and the position of the image sensor 4 may be moved.

Further, in the above-described embodiment, the description has been made such that the shift of the horizontal output timing of the image pickup signal of each field is given by the image pickup device 4, but the luminance signal processing of the digital processing circuit 14 after the image pickup device 4 outputs the luminance signal. It may be added before it is supplied to the unit 30.

Furthermore, in the above-described embodiment, as a solid-state image sensor
Although an example using the CCD solid-state image pickup device 4 is shown, the present invention is similarly applied when a solid-state image pickup device having a complementary color checker type color filter is used to obtain a high-resolution video signal. be able to.

[Effects of the Invention] As described above, according to the present invention, horizontal resolution is achieved by pixel shifting and signal processing without increasing the number of pixels of the solid-state image sensor and without increasing the number of solid-state image sensors. Therefore, high-resolution imaging can be performed without causing inconveniences such as high cost, large size, and difficulty in configuration.

[Brief description of the 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 shifting, FIG. 4 is an explanatory diagram of luminance signal processing, and FIG. FIG. 6 is a specific configuration diagram of the processing circuit, and FIG. 6 is an operation explanatory diagram of the luminance signal processing unit. 3 ... Optical path changing unit 4 ... CCD solid-state image sensor 5 ... Controller 6 ... Timing generator 14 ... Digital processing circuit 30 ... Luminance signal processing unit 40 ... Chroma signal processing unit

Claims (1)

(57) [Claims] 1. A solid-state image pickup device having a complementary color checkered color filter, and image positions picked up by pixel portions of the same color of the solid-state image pickup device are sequentially shifted horizontally by 1/2 pixel pitch for each field. A moving pixel shift mechanism, a time adjusting unit for adjusting the horizontal timing of the image pickup signal of each field output from the solid-state image sensor to the shift amount by the pixel moving mechanism, and the horizontal timing by the time adjusting unit. Signal processing means for obtaining a luminance signal by alternately adding the image pickup signals of one and the other two fields in the 1/2 pixel period among the adjusted image pickup signals of three fields from the solid-state image pickup device. A color image pickup device comprising.