JPH03132283A - Television camera - Google Patents

Abstract

PURPOSE:To prevent malfunction of a contour correction circuit and to prevent the deterioration in the picture quality by eliminating a modulation component of a filter coded in a zigzag pattern from an image pickup signal and clipping the resulting signal after and before a delay circuit. CONSTITUTION:The camera is provided with a low pass filter circuit 6 eliminating a modulation component of a filter coded in a zigzag pattern from an image pickup signal SS obtained from an image pickup element 2 and delay circuits 7, 9 delaying an output signal SDC 1 of the low pass filter circuit 6 by one horizontal scanning period. Moreover, 1st clip circuits 13, 15 clipping the output signal of the delay circuits 7, 9 and a 2nd clip circuit 11 clipping an output signal SDC of the low pass filter circuit 6 are provided. After the low pass filter circuit 6 eliminates the modulation component of the filter in the zigzag pattern coding, when the resulting signal is clipped before and after the delay circuits 7, 9, the image pickup signal SS is clipped at a lower signal level than the saturated level of the image pickup signal SS to avoid an error between an odd number line and an even number line. Thus, malfunction of the contour correction circuit is prevented to prevent deterioration in the picture quality.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a television camera, and is particularly suitable for application to a television camera that performs contour correction.

B Summary of the Invention According to the present invention, in a television camera, by clipping the averaged image signal, malfunction of the contour correction circuit can be effectively avoided and deterioration of image quality can be prevented.

C. Prior Art Conventionally, in some television cameras, a complementary color checkered coding filter is disposed in front of a solid-state image sensor to obtain an image signal.

In other words, as shown in FIG. 7, in the filter key of complementary color checkered coding, yellow Ye is
, cyan Cv and continuous magenta M6 and green G regions are alternately formed.

On the other hand, in a television camera, the charges accumulated in the image sensor are sequentially output at the timing of the rask scan, and at this time, two areas above and below the filter ↓ are simultaneously scanned.

Furthermore, in scanning even and odd fields, the areas to be simultaneously scanned are shifted by 1 fiJI area.

As a result, in scanning even-numbered lines, Yt +Ms, Cv +G, Yt +M*...
It is possible to obtain continuous imaging signals of..., whereas in scanning odd lines, Y, 10G, Cy +M
Continuous imaging signals can be obtained in the order of s, Yt + IC.

Therefore, since it is possible to synthesize yellow Y1, cyan Cv, and magenta M6 by synthesizing red and green, green and blue, and blue and red color signals, respectively, the luminance signal Y can be calculated by obtaining the average value of the image signal. Obtainable.

Furthermore, color signals can be synthesized by adding and subtracting the luminance signal Y and the color signals of yellow Y7, cyan CY% magenta M.

Furthermore, by shifting the scanning area by one area in even and odd fields, it is possible to obtain interlace-scanned luminance signals and color signals.

Therefore, a video signal can be synthesized by combining the luminance signal and the chrominance signal.

Problems to be solved by D invention By the way, yellow Y□, cyan Cv, magenta M6, green C
In the case of the color filter, the largest output signal is obtained from the pixel in which the yellow Y filter is arranged, whereas the signal level decreases in the order of magenta MG and green G.

Therefore, as shown in FIGS. 8 and 9, in the imaging signal SS, the average value is maintained at the same signal level E AIIIL during scanning of even and odd lines, and Yt+c, Cv
Compared to the scanning of consecutive odd lines in the order of +Ms, Yt +G, YE'+Me, Cv 10c, Yw
+Ms... The scanning of consecutive even lines is better for each filter Y! , Cv, M, and G, the signal level of the modulated signal component increases.

Therefore, as shown in Figures 1O and 11, when the subject becomes brighter, the saturation level Esay of signal processing circuits such as amplifier circuits is higher when scanning even-numbered lines than when scanning odd-numbered lines.
quickly (stand up)

In this case, if only the even lines are saturated and the odd lines are kept unsaturated, compared to scanning the odd lines,
When scanning even-numbered lines, the average value level E AWL is lower, resulting in an error in the average value level.

On the other hand, in the vertical contour correction circuit, the luminance signal is delayed by the horizontal scanning period, and signal components that are not correlated in the vertical direction are extracted and emphasized. When an error occurs in the average level of the imaging signal, the error component is emphasized and superimposed on the luminance signal.

Therefore, there is a problem in that the contour correction circuit incorrectly performs contour correction, and the quality of the displayed image deteriorates accordingly.

As one method to solve this problem, a method has been proposed in which the signal processing circuit detects whether or not it is saturated, and when the signal processing circuit reaches saturation, the operation of the contour correction circuit is stopped (Japanese Patent Application Laid-Open No. 1983-1999-1).
269873).

However, with this method, the configuration of the entire signal processing circuit becomes complicated, and as shown in Figure 12, the operation of the contour correction circuit is stopped when it is saturated, so the image quality changes rapidly before and after that, making it impractical for practical use. Above all, there were still some problems.

The present invention has been made in consideration of the above points, and aims to propose a television camera that can effectively avoid image quality deterioration.

E Means for Solving the Problem In the first invention, in order to solve the problem, an image sensor 2 is provided with a complementary color checkered coding filter on the front side, and a checkered pattern is obtained from the imaging signal SS obtained from the image sensor 2. A low-pass filter circuit 6 that removes modulation components of the pattern-coded filter; and a low-pass filter circuit 6.
A delay circuit 7.9 that delays the output signal SDC of the circuit by one horizontal scanning period, a first clip circuit 13.15 that clips the output signal of the delay circuit 7.9, and a first clip circuit 13.15 that clips the output signal SDC of the low-pass filter circuit 6. an addition circuit 17.19.20 that extracts uncorrelated signal components between adjacent scanning lines based on the output signals of the first and second clipping circuits 13.15 and 11; ．．
22, the output signals of the adder circuits 17, 19, 20, and 22, the input signals of the first clip circuit 13.15, the output signals of the first clip circuit 13.15, and the input signals of the second clip circuit 11. , or an adder circuit 23 that adds to the output signal of the second clip circuit 11.

Furthermore, in the second invention, there is provided an image sensor 2 in which a filter with complementary color checkerboard coding is arranged on the front surface, and a low-pass filter circuit 6 that removes a modulation component of the filter coded in a checkerboard pattern from an image signal SS obtained from the image sensor 2. , a clip circuit 11 that clips the output signal SDC of the low-pass filter circuit 6, and a delay circuit 7.7 that delays the output signal of the clip circuit 11 by one horizontal scanning period.
L, an adder circuit 17.19.20.22 for extracting uncorrelated signal components between adjacent scanning lines based on the output signals of the delay circuit 7.7L and the clip circuit 11, and an adder circuit 17.19. An addition circuit is provided for adding the output signal of 20.22 to the input signal of the clip circuit 11, the output signal of the clip circuit 11, or the output signal of the delay circuit 7.7L.

After the modulation component of the checkerboard coding filter is removed by the F-action low-pass filter circuit 6, the delay circuit 7.9 (7, 7
By clipping before and after L), it is possible to clip at a signal level lower than the level at which the imaging signal SS is saturated, and it is possible to avoid errors between odd-numbered lines and even-numbered lines and prevent malfunctions of the contour correction circuit. can.

G example An embodiment of the present invention will be described in detail below with reference to the drawings.

(G1) First Embodiment In FIG. 1, l indicates a television camera as a whole, and C has complementary color checkered coding filters arranged.
CD (charge coupled device)
) is obtained from the solid-state image sensor 2.

After amplifying the imaging signal SS, the amplifier circuit 4 removes the modulation component via a low-pass filter circuit (LPF) 6 (
(hereinafter referred to as averaging).

The delay circuits 7 and 9 are configured with a delay time of one horizontal scanning period, and the output signal S of the low-pass filter circuit 6
DC is sequentially delayed, so that the input signal of the delay circuit 7 and the output signal of the delay circuit 9 are advanced and delayed by one horizontal scanning period, respectively, with respect to the output signal of the delay circuit 7. 2 As shown in FIG. 2, the clip circuits 11, 13, and 15 each receive the input/output signal of the delay circuit 7 and the output signal of the delay circuit 9, and prevent each input signal from rising above a predetermined signal level VCL. is being done.

That is, as shown in FIG. 3, in the imaging signal SS, the signal level of the modulated signal component is different between the even-numbered lines and the odd-numbered lines, and the imaging signal SSE of the even-numbered line has a higher average level than that of the imaging signal SSo of the odd-numbered line. Value level E AV
Saturation occurs in the low L region.

Therefore, in this embodiment, the low-pass filter circuit 6
The image signal SDC averaged by the clip circuit 11
．． At 13.15, the average value level E at which the even-numbered line imaging signal SS is saturated is a signal level ■ below 5att. As a result, before the image signal SS is saturated, the image signal S is clipped by the clip circuit 11.13.15.
Clip DC.

In this way, the averaged image signal SDC can be clipped at a level below the average level at which errors occur on even and odd lines, and thus the occurrence of errors can be effectively avoided. can.

Therefore, malfunctions of the vertical contour correction circuit can be effectively avoided.

The clipping circuits 11, 13.15 respectively output clipped output signals to the tuning circuits 17.19.2°.

The amplifier circuits 17 and 20 weight the input signal to 1/2 and output it, whereas the amplifier circuit 19 outputs the input signal at the same signal level.

The adder circuit 22 subtracts the output signal of the amplifier circuit 17.20 from the output signal of the amplifier circuit 19, and thus adds uncorrelated signal components between three adjacent horizontal scanning lines via the adder circuit 22. An extracted contour correction signal can be obtained.

The adder circuit 23 adds the contour correction signal outputted from the adder circuit 22 to the input signal of the delay circuit 9, thereby obtaining a luminance signal Y in which the contour is emphasized in the vertical direction.

The color signal processing circuit 24 receives the input signal of the low-pass filter circuit 6 and the input signal of the delay circuit 9, performs predetermined signal processing, and creates color difference signals RY and BY.

The video signal synthesis circuit 26 generates a color difference signal RY.

After B-Y is modulated, it is added to the luminance signal Y to synthesize the video signal Sv.

In this way, by clipping the averaged imaging signal SDC, it is possible to effectively avoid malfunction of the vertical contour correction circuit, and accordingly, it is possible to prevent deterioration in image quality.

Ru.

Furthermore, as shown in Fig. 4, after the brightness signal Y is clipped by the clipping circuit 11.13.15, the contour is corrected by a certain amount, and the contour correction stops as in the conventional case. Sudden changes in image quality (FIG. 12) due to control can be effectively avoided.

Thus, in this embodiment, the delay circuit 7.9, the amplifier circuit 17.19.20 and the adder circuit 22.23 constitute a vertical contour correction circuit, and the amplifier circuit 17.19.20
The addition circuit 22 constitutes an addition circuit that extracts uncorrelated signal components between three adjacent scanning lines.

In the above configuration, the imaging signal SS output from the solid-state imaging element 2 is averaged by the low-pass filter circuit 6 via the amplifier circuit 4, and then output to the delay circuit 7.9.

The input/output signal of the delay circuit 7 and the output signal of the delay circuit 9 are as follows.
After being clipped by the clipping circuit 11.13.15 to a level below the average level at which errors occur on even and odd lines, it is output to the amplifier circuit 17.19.20, thereby validating the occurrence of errors. can be avoided.

The output signals of the amplifier circuits 17, 19, and 20 are sent to the adder circuit 22.
The output signals of the amplifier circuits 19 and 20 are subtracted from the output signal of the amplifier circuit 17, thereby obtaining a contour correction signal obtained by extracting uncorrelated signal components between adjacent horizontal scanning lines.

The contour correction signal is added to the human input signal of the delay circuit 9 in the adder circuit 23, thus obtaining a luminance signal Y in which the contour is emphasized in the vertical direction, and malfunctions of the contour correction circuit can be effectively avoided.

The luminance signal Y is synthesized by the video signal synthesis circuit 26 with the color difference signals R-Y and B-Y output from the color signal processing circuit 24, thus preventing deterioration of image quality and synthesizing the video signal Sv. be able to.

According to the above configuration, the malfunction of the contour correction circuit is effectively prevented by clipping the averaged imaging signal SDC and correcting the contour at a level below the average value level at which errors occur on even and odd lines. In this way, deterioration of image quality can be prevented.

(G2) Second Embodiment FIG. 5 shows parts corresponding to those in FIG. 1 with the same reference numerals,
A second embodiment of the invention is shown, in which the clip circuit 11 is placed before the delay circuit 7.7L.

That is, the output signal SDC of the low-pass filter circuit 6 is applied to the clip circuit 11, and the output signal of the clip circuit 11 is sequentially output to the delay circuit 7.7L.

Amplifier circuits 17, 19, and 20 are clip circuits 1 and 1, respectively.
1. Receive the output signal of the delay circuit 7.7L, adder circuit 22
Output to.

Thus, even if the clipping circuit 11 is placed before the delay circuit 7.7L, the averaged image signal SDC is clipped at a level below the average level at which errors occur on even and odd lines. Thus, the occurrence of errors can be effectively avoided.

Therefore, clip times j! Since ill is placed before the delay circuit a7.7L, the number of clipping circuits 11 can be reduced and malfunctions of the vertical contour correction circuit can be effectively avoided.

According to the configuration shown in FIG. 5, the clip circuit 11 is replaced by the delay circuit 7.
．． Placed in front of 7L, averaged imaging signal SDC
Even if clipped, the same effect as in the first embodiment can be obtained.

Furthermore, at this time, the clip circuit 11 is replaced by the delay circuit 7.7L.
By arranging the clip circuit in front of the clip circuit, the number of clip circuits can be reduced, and the overall configuration can be simplified accordingly compared to the first embodiment.

(G3) Third Embodiment In FIG. 6, numeral 30 indicates a television camera, which extracts uncorrelated signal components in two adjacent horizontal scan amounts.

That is, the input/output signals of the delay circuit 7 are transferred to the clip path 1.
1.15 to multiplier circuits 31 and 32, where they are amplified at the same amplification factor, and then output to subtraction circuit 33.

Thereby, uncorrelated signal line segments are extracted between two adjacent horizontal scanning lines via the subtraction circuit 33, and the signal components are output to the addition circuit 23.

Thus, in this embodiment, the delay circuit 7, the amplifier circuit 3
1.32, the addition circuit 23 and the subtraction circuit 33 constitute a vertical contour correction circuit that extracts uncorrelated signal line segments from between two adjacent horizontal scanning lines and performs contour correction.

According to the configuration shown in FIG. 6, even in the vertical contour correction circuit that extracts uncorrelated signal line segments from two adjacent horizontal scanning lines and performs contour correction, the averaged image signal SDC is clipped. As a result, malfunctions of the contour correction circuit can be effectively avoided, and the same effects as in the first embodiment can thus be obtained.

(G4) Other Embodiments Although the first and second embodiments have described the case in which delay circuits with a delay time of one horizontal scanning period are connected in series, the present invention is not limited to this. A delay circuit for two horizontal scanning periods may be used.

H Effects of the Invention As described above, according to the present invention, after removing the modulation components of the checkered-coded filter from the image signal, the errors between the odd and even lines are eliminated by clipping them before and after the delay circuit. This can be avoided, and malfunctions of the contour correction circuit can thus be prevented.

Therefore, it is possible to obtain a television camera that can prevent deterioration in image quality.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a television camera according to an embodiment of the present invention, FIGS. 2, 3, and 4 are characteristic curve diagrams for explaining its operation, and FIG. 5 is a block diagram showing a television camera according to an embodiment of the present invention. FIG. 6 is a block diagram showing the third embodiment, and FIG. 7 is a characteristic curve diagram for complementary color checkered torches. 1129.30...Television camera, 2.
...Solid-state image sensor, 4.17.19.2'013
1.32...Amplification circuit, 6...Low pass filter circuit, 7.7L19...Delay circuit,
11.13.15... Clip circuit, 22.2
3.33...Addition circuit.

Claims (2)

[Claims] (1) An image sensor having a filter with complementary color checkerboard coding arranged on the front surface; a low-pass filter circuit that removes a modulation component of the filter coded in the checkerboard pattern from an image signal obtained from the image sensor; a delay circuit that delays an output signal by one horizontal scanning period; a first clip circuit that clips the output signal of the delay circuit; a second clip circuit that clips the output signal of the low-pass filter circuit; and an adder circuit for extracting uncorrelated signal components between adjacent scanning lines based on the output signal of the second clip circuit; A television camera comprising: an addition circuit that adds to the output signal of the first clip circuit, the input signal of the second clip circuit, or the output signal of the second clip circuit. (2) an image sensor having a filter with complementary color checkerboard coding arranged on its front; a low-pass filter circuit that removes a modulation component of the filter coded in the checkerboard pattern from an image signal obtained from the image sensor; a clip circuit that clips an output signal; a delay circuit that delays the output signal of the clip circuit by one horizontal scanning period; and a delay circuit that delays the output signal of the clip circuit by one horizontal scanning period; It is characterized by comprising an adder circuit that extracts a signal component, and an adder circuit that adds the output signal of the adder circuit to the input signal of the clip circuit, the output signal of the clip circuit, or the output signal of the delay circuit. television camera.