JPS59225689A - Image pickup device - Google Patents

Abstract

PURPOSE:To eliminate effectively reflected distortion by detecting it when no vertical correlation exists in an image pickup signal of adjacent lines and replacing an original signal with a signal before 1H without residual side band. CONSTITUTION:The original signal and an image pickup signal delayed by 1 horizontal period and eliminated with its low frequency component are added at an adder 11. The output of the adder is inputted to a BPF17, one terminal A of a switch circuit 19 as a switching means, and a 1H delay circuit 20 as a delay means. When a side band remained uncancelled exists in the added output of the N-th line, its side band component is extracted through the BPF17, a detecting signal is outputted from a detecting circuit 18 so as to change over the switch 19 from the terminal A to a terminal B. That is, only the part having reflected distortion in the added signal is replaced selectively by the added signal before 1H without the distortion and the replaced signal is led to a matrix circuit as a signal processing means. Through the operation above, the reflected distortion is eliminated surely even if no vertical correlation exists, and excellent picture screen is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a color photographing system that allows moiré and the like to occur even when photographing objects with little correlation.

(Prior Art) For example, it is shown in FIG. Interline CODs are commonly used as imaging devices. 1 is a light receiving element,
They are arranged two-dimensionally at equal intervals vertically. To briefly explain the principle of operation, signal charges corresponding to picture element information are accumulated in each light receiving element for a certain accumulation time. These signal charges are then transferred to the vertical transfer register 3 via the transfer gate 2 using the transfer gate pulse (1/60 second period) (direction a).With the 0th vertical transfer lock, this signal charge is transferred line by line. The signal charges for one line read out (b direction) and transferred to the horizontal transfer register 4 are transferred to C by the horizontal transfer pulse.
It is read out sequentially in the direction. In this way, signal charges for one field are removed.

However, in this type of solid-state imaging device, input video information is spatially sampled using each unit picture element, and aliasing distortion described in FIG. 2 must be taken into consideration.

In other words, the modulation signal (Soc) is set at one sampling frequency (fo
), the reproducible modulation signal band is V2fc, as stated in the sampling theorem. Therefore, if the sampling frequency is sufficiently high for the modulation signal band, as shown in Fig. 2, the sampling frequency f in the high frequency component SDH of the modulation component SDC is
The sideband components SM of c overlap □ (,, j
The portion of %J becomes aliasing distortion, which causes a flickering phenomenon on the playback screen, which is undesirable. One way to remove this aliasing distortion is, for example, to limit the band of the modulation component SDC, but this Although it would be possible to increase the sampling frequency by increasing the number of pixels by 1, which is not a good idea, this poses a problem in terms of production, especially in terms of yield.

A special color filter is used to remove this aliasing distortion.
Some use an array and perform appropriate signal processing to obtain a high-band color image output.

For example, the color filter array shown in FIG. 6 is known. That is, in the N line, Cy (
These six color filters are arranged repeatedly in the order of cyan) - Yl (yellow) - W (white) as one cycle, and in the next (N♀1) line, the color filters are arranged in the order of yx - ay - G (green). are arranged repeatedly.

By using such a color filter array, as long as there is vertical correlation, the resolution can actually be improved as explained below.

FIG. 4 is a block diagram for realizing this. 5 is a color filter array, 6 is an imaging device element such as a GGD, and the imaging light that has passed through 5 is photoelectrically converted into a signal charge according to the color information in each pixel on 6, and this is done in the method described above. are read out sequentially.

To add more information about the signal band here, since the green signal is greatly involved in the luminance signal, this green modulation signal band is relatively wide (requires a bandwidth of 3.0 to 5.0M) (z
I'll save it until then. Further, the modulation signal band of red and blue light should be at least 500 KH2, and the resolution will not be affected much. In order to realize this, for example, an appropriate optical LPF or the like may be provided on the optical path.

The signal processing will be explained by referring to the frequency spectrum diagram in FIG. 5.

The imaging output output from the ccn 6 is subjected to an LPF 7 in which G sidebands generated around the carrier fc are removed in advance at a cutoff frequency of 1/2f (fc=1/τH). The imaging output thus obtained (Fig. 5 (a)) is input to the delay circuit 8 and the low-pass filter 9. The 0LPF 9 has a slightly higher frequency than the red and blue modulation signal bands, and fc' is the cutoff. frequency. The signal that has passed through this (Fig. 5 rc) is sent to the original signal a by the subtracter 10.
C is subtracted from , resulting in a low-frequency removed signal (FIG. 5 c)).

Here, the delay circuit 8 is for correcting the phase delay caused by the LPF 9. This signal d is subtracted by the subtracter 12 from the 1H previous signal which has been inputted through the 1H delay circuit 13. As a result, the modulated signal is canceled and only the sideband due to the variable m3 carrier is finally obtained (Fig. 5 (
f), (gn). These signals are respectively input to demodulators 14 and 15, in which y is obtained respectively. Furthermore, since the phase of the output of the subtractor 12 is inverted for each line, it is necessary to invert the Q N"B Ifll of the straw adjuster 14 and 15 for each line. On the other hand, the delay circuit 8
The original signal passed through is added to the signal e from which the low frequency was removed 1H before in the adder 11, and as a result, a modulated signal with canceled sidebands can be obtained. Note that this output has G+, (R1B) and G+, -(R+B) appearing repeatedly for each line. The six outputs obtained in this way are input to the matrix circuit 16 as a signal processing means, and finally the luminance signal and color difference signals (RY) and (B-Y) will be formed.

As explained above, when there is vertical correlation, aliasing distortion can be removed and the horizontal resolution can be substantially increased.

However, for example, if the captured image is vertical as shown in Figure 6(a),
If the earthworks in the □ direction are colored and there is no vertical correlation at the boundary, the sidebands will not be canceled even by addition,
As a result, aliasing distortion occurs at the boundary as shown in FIG. 6(b), resulting in flickering. K(N-
1) Assuming that mineral red light is captured up to the line and blue light is captured from the N-twin, a sideband remains at the addition output side of the N line as shown in FIG.

(Purpose) The object of the present invention is to provide a high-bandwidth imaging device that can obtain an image signal without aliasing distortion with a simple configuration even when an object without vertical correlation is imaged. 0 (Example) The present invention will be described in detail below based on Examples.

FIG. 8 shows a block diagram of the 14-image device of the present invention. Each number that is the same as in FIG. 4 represents the same block.
The color signal processing system is exactly the same as that shown in FIG. 4, so its explanation will be omitted.

The circuit is the same as the circuit shown in Figure 4 until the original signal and the low-frequency insurance signal delayed by one horizontal period are added in the adder 11, but the output of this addition is transmitted through the BPF 17 and the switching means. The signal is input to one terminal A of the switch circuit 19, and to the 1H delay circuit 20 as delay means. The output of the 1H delay circuit 20 is connected to the other terminal B of the switch circuit 19. A detection circuit 1B as a detection means is connected to the downstream of the BPF 17, and its output controls a switch circuit 19. In addition, BPF17 has a red band,
It covers the sideband band of the red and blue signals at the center around the sampling frequency 1/3fc of the red and blue signals.

In addition, 18 detection circuits are equipped with an α modulator that demodulates with z-aII or y@, as shown in Fig. 5 (f) and (g).
It may be constructed by detecting the level of this output.

In such a configuration, as shown in FIG. 7, if there is a sideband that remains without being canceled out in the addition output of the Nth line, that sideband component is extracted through the BPF 17 and sent from the detection circuit 18. The detection signal is output and the switch 19 is turned to A.
Switch from BK.

That is, only the portion of the added signal in which aliasing distortion exists is selectively switched with the added signal 1H before, in which this portion does not exist, and is guided to a matrix circuit as a signal processing means. By this operation, even when there is no vertical correlation, aliasing distortion can be reliably removed and a good screen can be obtained.

(Effect) OnoJEl's 1 Yellow Momme device 1 Koyore IJ:'As explained above, if there is no vertical correlation in the image signal of the border line, this is detected, and the residual side 1H before By replacing the original signal with a signal that does not have a waveband, aliasing distortion can be removed even when the imaging output does not have a waveband, and it is also effective even when aliasing distortion occurs partially in the horizontal direction. This can be removed.

[Brief explanation of drawings]

Figure 1 is a conceptual diagram of interline type COD, Figure 2 is a frequency spectrum diagram for explaining aliasing distortion, and Figure 3 is a diagram of the frequency spectrum for explaining aliasing distortion.
A diagram showing an example of Zusha filter arrangement, an explanatory diagram when the M4 correlation is hot, Fig. 7 is an explanatory diagram explaining this using a frequency spectrum, and Fig. 8 is a circuit of an embodiment of the throwing arrangement according to the present invention. It is a block diagram. 7.9M-1: LPF, 8, 13.20 is delay circuit, 1
0.12 is a subtracter, 11 is an adder, 14.15 is a balance adjuster, 161-t matrix circuit, 17 is a BPF, 18 is a detection circuit, and 19 is a switch circuit.

Claims (1)

[Claims] an imaging means with a color filter disposed on the front surface, a delay means for delaying the output of the imaging means, a signal processing means for processing the output of the imaging means, and an adjacent horizontal line in the output of the imaging means. and a switching means for selectively supplying the output of the imaging means or the output of the delaying means to a signal processing means according to the output state of the detection means. Device.