JPS5930386A - Color television camera - Google Patents

Abstract

PURPOSE:To correct almost completely the vertical color error, by adding a signal eliminating a part corresponding to a difference signal of a carrier signal obtained from the vertical correlation of a low frequency signal with a signal delaying it by 1H. CONSTITUTION:A chrominance carrier signal modulated at modulators 223, 224 and added 225 is gated 72, a signal of the part is eliminated, a signal delaying 226 by 1H is amplified 73 at the gate and this signal and a 1H delay signal are applied to an adder 227. Further, an output of a full-wave rectifier 71 is delayed 711 by 1H and only the gated part of the chrominance carrier signal through the 1H delay line 226 is amplified 712 for double gate's share with its gate signal and a signal through the 1H delay line 226 and the gate amplifier 73 is applied to an adder 227. Thus, the vertical color error appearing as the change in hue is prevented surely from the adder 227.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a color television camera device, and more particularly, to spatially modulates two colors of an object light image using a striped color filter, and then modulates electrical signals obtained through an image sensor. This invention relates to a simple color television camera device using a single element that separates modulated color signals of two colors using vertical correlation.

Configuration of Conventional Example and Its Problems First, an outline of the conventional single frequency separation type color television camera device will be explained as an example. The striped color filter shown in FIG.
) and yellow (Ye) striped filters are arranged alternately, and white (5) and cyan (Cy) striped filters are arranged at an angle so that the phase is reversed by 180 degrees for each horizontal scanning line. .When this filter is superimposed on the image sensor and the subject light image is formed on the image sensor, the output signal of the image sensor obtained is, in the case of scanning line (a), BSa(t)=(G+-H+-;) +(R1E8
) 5ina+ as scanning line (b) B Sb(t)=CG+7+7 )+(R-B)sin
It is expressed as oJt. FIG. 2 is a block diagram of a color television camera apparatus using an image pickup tube equipped with the striped color filter of FIG. In Figure 2 (201)
is an imaging lens, (202) is an imaging tube equipped with Daiden's striped color filter, and this output signal is sent to a preamplifier (202).
8) and its output is passed through a low-pass filter (
204), the gamma correction circuit (205) corrects the gamma value to approximately 0.45, and the luminance signal (
Yu). In addition, in order to use a part of the output signal of the preamplifier (20B) as a color signal, it is passed through a narrowband low-pass filter (206) and then subjected to gamma correction in a gamma correction circuit (207) to produce a narrowband luminance signal. (YL) and to perform vertical color error compensation, the output signal of the narrow band low-pass filter (206) is suppressed with a high amplitude part by a logarithmic circuit (208), and then the IH
The delay line (209) delays the horizontal scanning period, the subtracter (210) subtracts the signal from the original signal, and the signal is sent to the exponential circuit (2
11) and used as a correction signal for vertical color error compensation. Further, from the output signal of the preamplifier (208), only the spatially modulated modulated color signal is separated by a bandpass filter (212), and after being delayed by a -horizontal period by an IH delay line (21B), the multiplier (214) ) to obtain a signal modulated by the vertical color error correction signal, add and subtract this signal and the original signal by an adder (215) and a discriminator (216), respectively, and then add and subtract this signal from the original signal by a detector (217) and a detector (218), respectively. ) to obtain red and blue signals, gamma correction circuits (219) (220) perform gamma correction on these signals, and subtracters (221) (222) convert the narrowband luminance signal (Yt
, ) and subtract 2 of the (RY) signal and (B-Y) signal.
Obtain two color difference signals. Then, these two color difference signals are modulated by carrier waves having different phases at 0 degrees and 90 degrees by modulators (22B) and (224), and are added by an adder (225) to obtain a carrier color signal. Furthermore, in order to eliminate some interference that occurs at a frequency of 1/2 of the horizontal frequency due to the fact that the striped color filter does not have ideal characteristics or the nonlinearity of the image pickup tube characteristics, etc. The carrier color signal is delayed by a -horizontal period by an IH delay line (226), added equally by an adder (227), and further added to the luminance signal (YH) by an adder (228).
) to obtain a standard color television signal.

Next, the causes of vertical color errors and means for compensating for them will be explained with reference to FIGS. 8C and 4. In FIG. 4, the light amount of the subject at the wholesaler day, (f(+1) main entrance and (H+4), (f(+5) main exit) is (a) in FIG. 8, and (i+2).

(H+8) The amount of light from the subject at the main entrance is shown in FIG. 8(b).

Figure 4 is the output waveform at this time, Φ) is the narrowband luminance signal (Yt) waveform with the modulated color signal removed, [Yes]) is the separated waved red signal (solid line), and G) is the waveform (Yt). ) and (E) are identified and detected as a green signal (solid line). As can be seen from FIG. 4, even if the entire surface is the same color, the red and blue signals of parts with different lightness are reproduced as different signals compared to the narrowband luminance signal (YL).

This is called vertical color error, and it seriously degrades image quality. To correct this, conventionally, the waveform of a narrowband luminance signal (YL) is obtained by subtracting the original signal from the signal delayed by a horizontal period, and this signal is used to modulate the signal delayed by one horizontal period. By correcting the color signal (G)
) is obtained, and by adding and subtracting this signal and the waveform signal of ), the waveforms shown by broken lines (F) and (C) are obtained. These corrected waveforms are similar to the narrowband luminance signal (YL), so no color errors occur in the vertical portion.

However, this relationship holds true when the narrowband luminance signal (Yt,) and the modulated color signal increase as the amount of light increases. Whether it is an image pickup tube or a solid-state image pickup plate, in areas with low light intensity, as the light intensity increases, the output signal increases by 1 for both the narrowband luminance signal @ (Yt, ) and the modulated color signal, but once it reaches a certain level, it becomes saturated. I'll come.

This is because, in the case of an image pickup tube, it is limited by the beam current, and in the case of a solid-state image pickup plate, there is a finite volume in which the charge can be stored in the phototransistor in the light receiving section or in which the charge can be transferred in the transfer section. limited.

To explain this with reference to Fig. 4, saturation begins slightly past the point (b), and the modulated color signal tends to decrease, but the narrowband luminance signal (YL) (luminance signal (
Same goes for Yn), although the increasing trend slows down, the increasing trend continues until it reaches a complete saturation point. At this time, the modulated color signal becomes zero. This is because the striped color filter has high transmittance. This is because the saturation point is reached early and the saturation point is slow in areas where the transmittance is low.Therefore, in areas where the modulated color signal is decreasing in inverse proportion to the increase in light intensity, conventional correction means may have the opposite effect. This will be explained using Fig. 5. In Fig. 6, wholesale, (H+1), (H+6), (
[-1+7) The main entrance has the light intensity of (a) in Figure 8, (H+2)
, (H+8) The main entrance has the light intensity of (b), (H+4), (f(
+5) The main part is a waveform diagram when the light intensity is set to (C),
The main opening (H+4) and ([(+6)
The main opening is a portion shifted by one horizontal period from the rising and falling portions of the portion where the modulated color signal is inversely proportional to the amount of light.

Further, even if the amount of incident light and the modulated color signal are in a proportional relationship, a vertical color error similarly occurs in the portion where the color changes. This is shown in Figure 6. In the 6th prisoner, (mark, (f(+
The part 1) is magenta, (f(+2) to (E(+5)
) is orange, (t(+6) to (H+8) is blue), (4) is the image tube output signal waveform, and ) is the modulated color signal from the output waveform. The removed luminance signal, (C) is the vertical color error correction signal of the difference between the luminance signal delayed by one horizontal scanning period and the original signal, (
D) is a modulated color signal, 2) is a modulated color signal delayed by -horizontal period, the broken line portion is the signal waveform without color error correction, and the solid line portion is the waveform when correction is performed. (F) is a red signal obtained by adding and detecting (D) and (E), C)
is the green signal obtained by subtracting and detecting O) and (E), and (
F) (G) In both cases, the dashed line is the signal that should be there,
The solid line portion is the signal actually obtained. That is, the shaded areas are redundant areas, and the blank areas are insufficient areas. follow °
The part appears as a color error. In particular, due to the change in hue, that part stands out and becomes difficult to see.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned drawbacks, and provides a color television camera device that can almost completely correct vertical color errors, and in particular can reliably prevent vertical color errors from appearing as changes in hue. With the goal.

Structure of the Invention In order to achieve the above object, the color television camera device of the present invention spatially modulates at least two different colors using a mosaic or stripe color filter, and separates the signals obtained thereby. A color television camera device 1 uses vertical correlation to obtain different two-color signals, and uses these signals and a low-frequency signal to obtain a color television signal. a first means for removing or suppressing a carrier color signal or a portion of the color difference signal corresponding to the difference signal using a difference signal; and a signal obtained by the first means and a signal obtained by delaying the signal by one horizontal period. This configuration is provided with a second means for adding the same.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 7 shows the inside of a block of a color television camera apparatus, and the same components as those shown in FIG. 2 are designated by the numeral ``-'' and their explanation will be omitted. In FIG. 7, (71) is a double wave detection circuit, (72) is a gate circuit, and (78) is a gate amplifier. In order to obtain the vertical color error correction signal, the signal obtained by subtracting the signal delayed by the CI H delay line (209) through the logarithmic circuit (208) and the original signal that is not delayed by the subtractor (2i0) is obtained. , the signal generated below the reference level in the dual-wave detection circuit (71) is inverted and used as a gate signal. On the other hand, the modulator (2
28) (224), and adder (225) adds ν
A gate circuit (72) gates the carrier color signal with the gate signal, removes that part of the signal, and outputs the signal delayed by a -horizontal period in an IH delay line (226) to the gate circuit (72). It is amplified by a gate amplifier (78) that changes the amplification degree of that part depending on the signal, and this signal and IH delay line (2
26) are combined with the input side signal by an adder (227) to obtain a carrier color signal. This waveform is shown in FIG.

In Figure 8, 'C1θ■) is the (RY) signal shown in Figure 6 and obtained from No. 1316, (I) is the same < (B-Y) signal, and α■ (1) is the l+2)th signal. 01+6) A color error signal occurs in the main image. (J) is the waveform obtained by detecting the vertical color error correction signal in FIG. 6(c) by the dual-wave detection circuit (71), (K) is the waveform obtained by gating the (B) is the waveform obtained by gating the (I) waveform with (J), and (L) is the waveform obtained by passing the wholesale through the IH delay line and adding equal decoration (R-
Y) signal, the broken part is the gate amplifier (78)
The waveform when only the gate waveform part is doubled is 0.
o (to)) is a (B-Y) waveform similar to (L),
The same applies to the broken line portion. As can be seen, the color difference signal requires only a change in amplitude without time lag or phase shift during one horizontal period, so there is little deterioration in image quality. In the above explanation, (RY) and (B-Y) are used to make it easier to understand, but in reality, the carrier color signal is used for 0 as shown in FIG.

However, it goes without saying that the same effect can be obtained even if such processing is performed before the condition becomes sad as shown in FIG.

For further completeness, the dashed line in FIG. 7 may be added. This will be explained below.

In FIG. 7, the output of the double wave detection circuit (71) is again I
The H delay line (711) delays the carrier color signal by a -horizontal period, and the gate signal is used to amplify the carrier color signal before passing through the IH delay line (226) by a factor of 2 using the gate amplifier (712), after which the IH delay is applied. The signal passing through the line (226) and the gate amplifier (78) is combined in an adder (227) to obtain a carrier color signal. Furthermore, since the carrier color signal is delayed by one horizontal period as a whole, if a wideband IH delay line (718) is provided to delay the luminance signal (Yl()) by that amount, a nearly perfect image can be obtained. will be explained using Fig. 9 C. In Fig. 9, (J) is the same gate signal as in Fig. 8, and (0) is the gate signal of (J) delayed by one and a half periods. The signal, (I)) is the (RY) signal which is twice the delay gate signal fop power, and (Q) is the gate signal with that part doubled.
Double amplification and IH delay (R-Y) (No. 1, Kin) is (P)
(R-Y) signal, (S) is a delay gate and its part is amplified twice (B-η signal, (
1) (delayed (B-Y') signal which amplified that part twice with T month J. , (V) are the luminance signals delayed by IH, and are time-shifted from σ→ and (D), indicating that a standard color television signal without vertical color error or color shift can be obtained.

Note that the multiplication circuit (214) is originally unnecessary, but
Separating the vertical color error correction signal into the gate signal requires some margin, so if the correction signal has a small amplitude, the multiplication circuit (214) is used to correct it, and the gate signal is only used if the amplitude is large. The method used is practical. Therefore, if a multiplier circuit (214) is used only for correction signals with extremely small amplitudes, a logarithmic circuit (208) or an exponential circuit (211) can be used.
can be omitted.

In this way, at least vertical color errors that change the phase do not occur, and by adding a broadband IH delay line, etc., almost perfect image quality can be obtained. It goes without saying that the present invention can also be applied to a color television camera device using a solid-state image sensor.

Effects of the Invention As described above, according to the present invention, vertical color errors can be almost completely corrected, and in particular, it is possible to reliably prevent vertical color errors from appearing as changes in hue, so that extremely beautiful images can be obtained. .

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an arrangement of stripe filters of a single frequency separation method, and the second reason is a block diagram of a conventional single-tube color television camera device using the filter shown in FIG.
Fig. 8 is an explanatory diagram of the input/output characteristics of the image pickup tube using the filter shown in Fig. 1, Fig. 4 is a waveform diagram explaining the causes of vertical color errors, and Fig. 5 is a diagram illustrating the causes of vertical color errors that cannot be compensated by conventional compensation means. FIG. 6 is a waveform diagram explaining that there is a range. FIG. 6 is a waveform diagram explaining that vertical color errors occur even when the colors are different. FIG. 7 is a waveform diagram explaining that there is a range. FIG. The figure is a waveform diagram for explaining the simplest color error correction in an embodiment of the present invention, and FIG. 9 is a waveform diagram for explaining the most complete color error correction in an embodiment of the present invention. It is. (71)...Double wave detection circuit, (72)...Gate circuit, (7B) (712)...Gate amplifier, (208
)...logarithmic circuit, (209) (226) (711)
...IH delay line, (210) ...subtractor, (228
)(224)...Modulator, (225)...Adder,
(718)...Wideband IH delay line. Agent Yoshihiro Morimoto Figure f Figure 4 Figure 5 Figure 6 Figure 9 (A2 Figure 9 (Rof)

Claims (1)

[Claims] 1. Spatial modulation of at least two different colors using a mosaic or striped color filter, separating the signals obtained thereby, and obtaining signals of the two different colors using vertical correlation. ,
In a color television camera device that obtains a color television signal using these signals and a low frequency signal, a difference signal obtained by vertical correlation of the low frequency signal is used to correspond to the difference signal of the carrier signal or color difference signal. A color television camera device comprising: a first means for removing or suppressing a portion; and a second means for equally adding a signal obtained by the first means and a signal obtained by delaying the signal by one horizontal period. . λ The second means is configured to equally add the signal obtained by the first means and a signal obtained by delaying the signal by one horizontal period and then amplifying the portion corresponding to the difference signal. 2. The color television camera device according to item 1. 8. The second means delays the difference signal by one horizontal period and uses this signal to amplify a portion of the signal obtained from the first means 1 corresponding to the delayed difference signal; Claims 1 or 2 include a structure in which the signal obtained by the means described above is equally added to the signal delayed by one horizontal period.
Color television camera device as described in Section 1. 4. The output of the second means is synthesized with a signal obtained by delaying a low frequency signal of the image sensor output by one horizontal period to obtain a standard color television signal.
9. The color television camera device according to any one of items 8 to 8.