JPH043715B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a color image signal synthesis method for synthesizing two color image signals to obtain a new composite color image signal.

(Prior Art) Conventionally, as a simple method for synthesizing two color image signals, a method has been used in which color image signals in the form of television signals are directly mixed.

Figure 1 shows a rotating head type magnetic recording and reproducing device (hereinafter referred to as VTR) that can obtain a composite color image signal using such a conventional composition method and record it.
FIG. 1 is a magnetic tape, and 2 is a cylindrical tape guide drum on which the tape 1 is wound approximately 180 degrees diagonally. 3 is a supply reel for the magnetic tape 1, and 4 is a take-up reel. The magnetic tape 1 runs in the direction of arrow 5, and the drum 2 rotates in the direction of arrow 6. Heads 7 and 7' are used during normal recording and reproduction, and heads 8 and 8' are used to record composite color image signals.

During normal recording, the color image signal input from the input terminal 10 is supplied to the recording signal processing circuit 12 via the changeover switch 11, and after being converted into a signal form suitable for magnetic recording by the recording signal processing circuit 12, the changeover switch 13 is turned on. The data are recorded on the magnetic tape 1 by the heads 7, 7' via the magnetic tape 1. At this time, switch 11 and switch 13 are each connected to the R side in the figure.

During normal playback, switch 13 and switch 15 are each connected to the P side in the figure. The reproduced color image signal reproduced by the heads 7 and 7' is supplied to the reproduced signal processing circuit 14 via the switch 13 and returned to the television signal.
It is output from terminal 16 via.

FIG. 2 is a diagram showing the state on the magnetic tape 1 recorded by the VTR shown in FIG. 1. 19A, 19
B, 19C, and 19D are tracks on which one field of color image signals are each recorded.If track 19A is recorded in head 7, track 19B is recorded in head 7', and track 19C is recorded in head 7. If the head 7 is now in the position shown in FIG. 2 and tracing the track 19C, the head 8 is arranged so as to trace the same part of the adjacent track 19D. Head 7'
The arrangement of the head 8' and the head 8' is also similar.

Next, the operation when recording a composite color image signal using the heads 8 and 8' will be explained. In this case, the switch 13 is connected to the P side in the figure, and the switch 11 and the switch 15 are each connected to the M side in the figure. The color image signal reproduced by the heads 7 and 7' is returned to a television signal by the reproduced signal processing circuit 14, and is supplied to the mixer 17 via the switch 15, where it is mixed with a new television signal input from the terminal 10. be done. At this time, the rotation servo of the drum 2 is performed using a vertical synchronization signal separated from the new television signal inputted from the terminal 10. Therefore, the timings of the reproduced color television signal and the new television signal coincide.
The composite color image signal obtained by the mixer 7 is converted into a signal form suitable for magnetic recording again by the recording signal processing circuit 18, and is then converted into a signal form suitable for magnetic recording by the heads 8, 8', on the track next to the track being traced by the heads 7, 7'. Yes, the data is recorded on the track that has already been played back by the heads 7, 7'.

However, when color image signals are synthesized using this method, there arise problems such as moiré of the color signals and changes in hue. That is, in the case of multiplexing, it is difficult to completely match the phases of one color signal and the other color signal. Moreover, by multiplexing both color signals, they influence each other and cause a phase shift, that is, a hue shift.

Therefore, conventionally, in television broadcasting, etc., a method has been used to synthesize two color image signals by switching and outputting the two color image signals according to the luminance signal level and the phase (hue) of the color signal of one color image signal. There is.

However, for example, when creating a switching signal according to the luminance signal level, a high luminance (white) or low luminance (black) background must be placed on the portion of one color image signal that is not desired to be combined. This can be achieved by shining a spotlight on the subject you want to photograph or by photographing a white wall in the background.
The shooting itself turned into a very large-scale project.

Furthermore, since the image signals are switched, the image signals that are discarded due to this switching are not reflected in the composite image signal at all. Therefore, the effect of duplicating two types of screens cannot be expected.

Furthermore, if the color image signal used to create the switching signal is close to the threshold value, there will be too many switching parts in one screen, making the screen very unsightly. Put it away.

(Objective) In view of the above-mentioned drawbacks, the present invention provides a color image that can obtain a good composite image signal without any unsightly appearance due to hue shift or switching without any special efforts when photographing color image signals to be composited. The purpose is to present a signal synthesis method.

(Example) FIG. 3 is a diagram showing a magnetic sheet recording/reproducing apparatus as an example of the synthesis method of the present invention. This embodiment is an example in which a color image signal corresponding to one field of television signals is recorded on a concentric recording locus on a rotating magnetic sheet, and is applied to a magnetic recording/reproducing apparatus that reproduces from the recording locus.

In this configuration, the operation during normal recording will first be explained. In FIG. 3, reference numeral 20 denotes a terminal to which a color television signal is input, and in this embodiment, the input color image signal will be described as an NTSC signal. 21 is a high frequency filter (hereinafter referred to as HPF) that separates the carrier color signal from the NTSC signal.
22 is a low frequency filter (hereinafter referred to as LPF) that separates the luminance signal. The luminance signal separated by the LPF 22 is supplied to the frequency modulator 25 through the terminals of the switches 23 and 24 shown as N in the figure. The FM modulated luminance signal frequency-modulated (hereinafter referred to as FM modulation) by the frequency modulator 25 is sent to the amplifier circuit 2.
6 to a mixer 27.

On the other hand, the carrier color signal separated by the HPF 21 is sent to the frequency converter 2 via the illustrated A terminal of the switch 28.
9. The color signal frequency-converted to a low frequency band by the frequency converter 29 is supplied to the mixer 27 via the amplifier circuit 30 and mixed with the above-mentioned FM modulated luminance signal. 1/60 second) is extracted and switch 32
The information is recorded on the magnetic sheet 36 by the recording/reproducing head 35 via the illustrated R terminal and the illustrated N terminal of each of the switches 33 and 34 while forming a concentric recording locus 37.

At this time, a vertical synchronizing signal is extracted from the luminance signal output from the LPF 22 by a vertical synchronizing signal separation circuit 38 and is supplied to a phase comparator circuit 40 via the R side of a switch 39. On the other hand, 41 is a phase detection pulse generation (hereinafter referred to as PG) magnet, and 42 is a
PG head, obtained from PG head 42
The PG pulse is supplied to the phase comparison circuit 40 via the R side terminal of the switch 43. Phase comparison circuit 40
The phase error output between the vertical synchronization signal and the PG pulse obtained is supplied to the control signal addition circuit 45 via the N-side terminal of the switch 44, and the speed control signal obtained by the speed control circuit 46 based on the PG pulse is supplied to the control signal addition circuit 45. is added. The rotation control signal for the motor 47 obtained by the control signal addition circuit 45 is supplied to a motor drive circuit 48 to control and drive the motor 47, and the phase is adjusted such that the vertical synchronization signal is recorded at a predetermined location on the magnetic sheet 36. is controlled to rotate the magnetic sheet 36 at a constant speed of 60 revolutions per second. 48 is an arrow indicating the direction of rotation of the magnetic sheet 36.

Next, the operation of the magnetic recording/reproducing apparatus shown in FIG. 3 during normal reproduction will be explained. In this case, switch 3
2, 39, and 43 are each connected to the P side terminal. The color image signal of one field reproduced by the recording/reproducing head 35 is sent to the N side terminals of switches 33 and 34,
The signal is supplied to the preamplifier 50 via the P-side terminal of the switch 32 and the N-side terminal of the switch 49. Then, from the reproduced color image signal amplified by the preamplifier 50, the HPF 51 converts the FM modulated luminance signal into the LPF 52.
The low-pass converted color signals are separated. The FM modulated luminance signal is FM demodulated (hereinafter referred to as
At the same time, it is processed to form a television signal. In other words, in order to eliminate the disturbance in the horizontal synchronization signal caused by repeatedly reproducing the image signal of the same field, 1/
Processing such as mutually outputting a signal via a 2-horizontal scanning period delay line (hereinafter referred to as 1/2 HDL) and a signal not via a 2-horizontal scanning period delay line every 1 field period is performed. However, the vertical synchronization signal is always output without going through 1/2HDL.

The reproduced luminance signal which has been processed in this manner and is in the form of a television signal is supplied to the mixer 56 via the N side of the switch 54 and the amplifier circuit 55. on the other hand
The low-frequency conversion color signal separated by the LPF 52 is frequency-converted to the original band by the frequency converter 57, and processed to form the television signal format as described above. The reproduced color signal thus obtained is supplied to the mixer 56 via the amplifier circuit 58.
At step 6, the signal is mixed with a reproduced luminance signal via an amplifier circuit 55 and outputted from an output terminal 59 as a reproduced color television signal.

During normal playback, the vertical synchronization signal separation circuit 60
The reproduced vertical synchronizing signal separated by is supplied to the phase comparator circuit 40 via the P side terminal of the switch 39,
Reference oscillator 61 via P side terminal of switch 43
The phase is compared with the output reference signal of The phase control signal obtained by the phase comparator circuit 40 is added to the speed control signal by a control signal addition circuit 45 in the same way as during normal recording. The rotation of the motor 47 is controlled via a motor drive circuit 48.

The operation of obtaining a composite color image signal in the magnetic recording/reproducing apparatus of this embodiment will be described below. At this time, switches 23, 24, 33, 34, 4
All switches 4, 49 and 54 are connected to the M side terminal, switch 32 is connected to the R side terminal and switch 7 is connected to the R side terminal.
9 are respectively connected to the P side terminals.

The color image signal recorded on the concentric recording locus 37 on the magnetic sheet 36 is reproduced by the auxiliary head 62. The reproduced color image signal is separated into an FM modulated luminance signal and a low frequency conversion color signal by the HPF 51 and LPF 52 as in normal reproduction, and the FM modulated luminance signal is converted to the DEM and the above-mentioned horizontal synchronization signal by the FM demodulator 57. Processing is performed to eliminate the disturbance. On the other hand, the low frequency converted color signal is returned to its original band by the frequency converter 57, and the same processing is performed. The reproduced luminance signal obtained in this way is the M of the switch 54.
The reproduced color signal is supplied to the adder 63 and the differential amplifier 64 through the side terminal, and the reproduced color signal is sent to the color signal changeover switch 28.
is supplied to the C terminal of

On the other hand, the color television signal to be combined with this reproduced color image signal is supplied from the terminal 20 in the same way as during recording, and the carrier color signal is
The luminance signals are separated by the LPF 22. The separated luminance signal is supplied to an adder 63 and a differential amplifier 64 via the M-side terminal of the switch 23.
The carrier color signal separated by HPF21 is sent to switch 2.
Connected to the A terminal of 8.

In the differential amplifier 64, the color image signal reproduced from the magnetic sheet 36 (hereinafter referred to as a reproduced signal)
A level proportional to the difference between the luminance signal level of the color image signal (hereinafter referred to as input signal) newly input from the terminal 20 is obtained, and this is supplied to the stretching circuit 65. The stretch circuit 65 changes the switch 28, which is always connected to the A terminal during normal recording, from A to A according to the output of the differential amplifier 64.
Connect to either terminal C.

Generally, when obtaining a composite color image, the color with the higher luminance signal level of the two color image signals in each part of the image is important, and the image will be easier to see if that color is output. Therefore, the differential amplifier 6
The brightness signal levels of the reproduced signal and the input signal are compared in each part of the image by the output of 4, and the switch 28 is changed so that the stretch circuit 65 outputs the color signal of the image signal with the higher brightness signal level. . That is, taking the device shown in FIG. 3 as an example, when the luminance signal level of the reproduced signal is high, the switch 28 is connected to the C terminal, and when the luminance signal level of the input signal is high, the switch 28 is connected to the A terminal. . 66
is a threshold adjustment circuit which adjusts the threshold level of the stretch circuit 65. For example, if the luminance signal of the reproduced signal is a positive input and the luminance signal of the input signal is a negative input in the differential amplifier 64, the threshold level is set to 0 level in the above example, and if you want to give more importance to the color signal of the reproduced signal. In this case, set the threshold level to a negative level, and conversely, if you want to give more importance to the color signal of the input signal, set the threshold level to a positive level. By doing this, more color signals of the color image signal to be emphasized are outputted.

Since the color burst signal is multiplexed on the back porch of the horizontal synchronizing signal, the luminance signal level of that portion is zero level for both the reproduced signal and the input signal. Therefore, in the configuration shown in FIG. 3, the threshold adjustment circuit 66 may set the threshold level to a positive or negative level as described above, and output the color burst signal in the reproduced signal or the color burst signal in the input signal.

Although not shown, another method is to multiplex the average value of two color burst signals (although they should be the same signal, there may be a phase shift, etc.)
A possible method is to use the color burst signal of the reproduced signal or the input signal, which color signal is output for a longer period of time.

The thus obtained composite color signal is again converted to a low frequency signal by the frequency converter 29 and is supplied to the mixer 27 via the amplifier 30. On the other hand, the luminance signal is obtained by adding the luminance signal of the input signal and the luminance signal of the reproduced signal in an adder 63, and then FM modulation and related processing are performed in the FM modulator 25 via the M side terminal of the switch 24. It is supplied to the mixer 27 through the. The composite image signal obtained by the mixer 27 is extracted for one field by the gate circuit 31 and sent to the magnetic sheet 36 via the R side terminal of the switch 32, the M side terminal of the switch 33, the delay circuit 67, and the M side terminal of the switch 34. recorded. The delay circuit 67 is for correcting a time axis shift due to a phase shift between the heads 35 and 62, and when this composite signal is recorded, it is recorded at the same position as during normal recording.

Next, the operation of the servo system during recording of this composite color image signal will be explained. The vertical synchronization signal separation circuit 38 separates the vertical synchronization signal from the luminance signal of the input signal, and the vertical synchronization signal separation circuit 60 separates the vertical synchronization signal from the luminance signal of the reproduced signal.
These two vertical synchronization signals are each sent to a phase comparator circuit 68.
The phase comparison circuit 68 supplies a phase control signal to the control signal addition circuit 45 via the M side terminal of the switch 44 in order to match the phases of both vertical synchronization signals. Based on the PG pulse obtained from this phase control signal PG head 42, the speed control circuit 46
The signal is added to the speed control signal obtained in step 1, drives the motor drive circuit 48, and controls the motor 47. In this way, the phases of the reproduced signal and the input signal are matched.

According to the embodiment described above, since the color signal of either the input signal or the reproduced signal is output, the two color signals do not influence each other. Also, there is no longer a need to use special techniques when shooting. Then, a good composite color image signal can be combined and recorded as a still image using one device.

FIG. 4 is a diagram showing an example in which the synthesis method of the present invention is applied to a _VTR . Components similar to those in FIG. 3 are given the same numbers. In the case of VCR,
Since there are almost no changes to the signal processing circuit, a description thereof will be omitted.

First, the operation during normal recording will be explained. The color television signal input from the terminal 20 is processed as described above and then transferred to the magnetic tape 69.
Each field is recorded by the heads 71 and 72 on the rotating drum 70. Switching between head 71 and head 72 is performed by a head switching circuit 73. Although not shown, the head switching circuit 73 is controlled by a vertical synchronizing signal separated from the input color television signal. That is, it is controlled by a vertical synchronizing signal separated by a vertical synchronizing signal separation circuit 38' in the figure.

The rotation of the drum 70 is controlled by the PG head 42' in the same way as the rotation of the magnetic sheet 36 in FIG.
A speed control signal is obtained by the PG pulse obtained from the PG magnet 41', and a phase control signal obtained by comparing the phases of the vertical synchronization signal and the PG pulse separated by the vertical synchronization separation circuit 38' with the phase comparator 40'. The control signal addition circuit 45' adds the signals to control the rotation of the rotary drum 70.

A capstan motor 75 that drives the capstan 74 obtains a speed control signal in a speed control circuit 77 based on an FG signal obtained from a signal generator 76 for detecting rotation of the capstan motor 75 (hereinafter referred to as FG). By driving the capstan motor drive circuit 78 using the speed control signal, the rotation speed is controlled to be constant.

On the other hand, the vertical synchronization signal separated by the vertical synchronization signal separation circuit 38' is sent to the control head 80 as a control signal via the R side terminal of the switch 79.
The data is recorded on the edge of the magnetic tape 69.

Next, the operation during normal playback will be explained. The color image signals reproduced by the heads 71 and 72 pass through the head switching circuit 73 and the P side terminal of the switch 32, undergo signal processing as described above, and are converted into the original color television signal form and output from the output terminal 59. . Note that the head switching circuit 73 is controlled by a vertical synchronizing signal separated from the reproduced luminance signal.

The drum servo during normal playback is similar to the control of the rotating magnetic sheet in FIG. A circuit 40' compares the phases and obtains a phase control signal. The speed control signal obtained from the speed control circuit 46' and this phase control signal are added in a control signal addition circuit 45', and the drum motor 70 is driven via the drum motor drive circuit 48'.

Next, control of the capstan 74 will be explained. First, a speed control signal obtained by the speed control circuit 77 is obtained based on the FG signal obtained in the same manner as during recording, and is supplied to the control signal addition circuit 81. Also, the control signal recorded on one end of the tape 69 during normal recording is reproduced by the control head 80.
This control signal is supplied to the phase comparison circuit 82 via the switch 79. This phase comparison circuit 8
2, the vertical synchronization signal separation circuit 6 is selected from the reproduced luminance signal.
The phases of the vertical synchronizing signal and the reproduction control signal separated at 0' are compared. The output of the phase comparison circuit 82 is supplied as a phase control signal to the control signal addition circuit 81, which adds the speed control signal, and the output of the control signal addition circuit 81 is used to add the speed control signal to the capstan motor drive circuit 78. is under control.

Next, the operation when obtaining a composite color image signal will be explained. Heads 83 and 84 are auxiliary heads for reproduction only, and are arranged to scan the magnetic tape 69 in advance of heads 71 and 72, respectively. The color image signals reproduced by the heads 83 and 84 are supplied to a reproduced signal processing circuit via a head switching circuit 85 and the M side terminal of the switch 49. Head switching circuit 85 is controlled by a vertical synchronizing signal separated from the color image signal reproduced by heads 83 and 84. That is, it is controlled by the vertical synchronization signal separated by the vertical synchronization separation circuit 60'.

A color television signal to be combined with this reproduced color image signal is inputted from the input terminal 20, and a combined color image signal is obtained similarly to the apparatus shown in FIG. This composite color image signal is recorded by the heads 71 and 72 via the switch 32, the switch 33, the delay circuit 67, the switch 34, and the head switching circuit 73 on the track on the magnetic tape 69 that the heads 83 and 84 have just traced. Ru. Note that the delay circuit 67 delays by the phase difference between the heads 71, 72 and the heads 83, 84, but if the heads are arranged as shown in FIG. 2, the delay circuit 67 is not necessary.
In this case, the head switching circuit 73 converts the vertical synchronizing signal separated from the composite color image signal delayed by the delay circuit 67 or the vertical synchronizing signal separated from the reproduced signal and the input signal by the delay time of the delay circuit 67. Controlled by a delayed signal.

The rotation control of the drum 70 when obtaining a composite color image signal is also similar to the control of the magnetic sheet in the apparatus shown in FIG. First, a speed control signal is generated using a PG pulse and is supplied to the control signal addition circuit 81.
On the other hand, as a phase control signal, a vertical synchronization signal separated from each of the reproduced signal and input signal is sent to the phase comparator 6.
The phase is compared at 8' and the phase error signal is used.
This phase error signal is supplied to the control signal addition circuit 45' via the M side terminal of the switch 44' and added to the speed control signal. and control signal addition circuit 4
The rotation control signal obtained at step 5' is supplied to the drum motor drive circuit 48' to control the rotation of the drum 70.

Next, the control of the capstan 74 when obtaining a composite color image signal is exactly the same as during normal reproduction, since the heads 83 and 84 are traced as if the heads 71 and 72 are tracing them.

By configuring the VTR as described above, it is possible to obtain a composite color image signal without causing color unevenness or hue shift, and without using special techniques during shooting. Further, it is possible to synthesize and record such a good composite image signal of a moving image using a single device.

FIG. 5 is a diagram showing another example of the synthesis method of the present invention. In FIGS. 3 and 4, the explanation was given using an example of a device that records and reproduces color image signals.
In FIG. 5, only the configuration of the parts to be synthesized is shown for the sake of simplicity. 90 is a terminal to which the first luminance signal separated from the first color image signal is input; 91
Similarly, 92 is a terminal to which the first color signal separated from the first color image signal is input, 92 is the terminal to which the second luminance signal separated from the second color image signal is input, and 93 is the same terminal. This is a terminal into which a second color signal separated from the second color image signal is input.

The first luminance signal and the second luminance signal are each supplied to an adder 94 to obtain a composite luminance signal. This composite luminance signal is supplied to mixer 95. For example, if you add an intermediate-level luminance signal (corresponding to gray) and an intermediate-level luminance signal, it seems that a high-level luminance signal will be obtained.
Generally, in systems that handle such image signals,
An automatic gain control circuit is provided to obtain a composite luminance signal that has an average level even when added.

On the other hand, the first color signal and the second color signal are supplied to the A terminal and C terminal of the switch 96, respectively. 1st
The luminance signal and the second luminance signal are each further supplied to a level comparison circuit 97 for level comparison.
Reference numeral 98 denotes a switching signal generation circuit that receives the output of the level comparison circuit 97 and generates a switching signal for switching the connection of the switch 96.

6A to 6D are diagrams showing examples of input/output characteristics of the switching signal generation circuit 98.

According to the characteristics shown in FIG. 6A, when the level of the first luminance signal is higher than the level of the second luminance signal, that is, when the output of the level comparison circuit 97 is a positive output, the switching signal generation circuit 98 switches the switch 96. It outputs an output (high level in the figure) that connects the terminal A to the terminal A shown in the figure. Conversely, when the level of the second luminance signal is higher than the level of the first luminance signal, an output is made that connects the switch 96 to the illustrated terminal C. This characteristic takes into account that the color with the higher luminance signal in the two color image signals is important, and the results are similar to those of the embodiments shown in FIGS. 3 and 4. get. Further, as shown in the explanation of FIGS. 3 and 4, it is possible to give importance to the first or second color image signal. In other words, in order to give importance to the first color image signal, it is sufficient to shift the characteristics of the switching signal generation circuit 98 in the direction of arrow 99 in FIG. 6A, and vice versa. If you want to have it, just shift it in the direction of arrow 100.

The characteristics shown in Figure 6B are based on the fact that when there is almost no difference between the level of the first luminance signal and the level of the second luminance signal, it will be unnatural no matter which color signal is output. I'm putting it in. That is, if there is a certain level difference, the switch 96 is connected to the A terminal or the C terminal, and either the first color signal or the second color signal is mixed with the aforementioned composite luminance signal in the mixer 95. If the level difference is small, the switch 96 is connected to the low terminal, and neither the first color signal nor the second color signal is supplied to the mixer 95, and a black and white signal is obtained for that portion.

The characteristics shown in FIGS. 6C and 6D show the characteristics when color signals are not multiplexed when the difference between the level of the first luminance signal and the level of the second luminance signal is too large. By shifting the characteristics shown in FIGS. 6B, C, and D in the direction of arrow 99 or arrow 100, it is possible to emphasize the first or second image signal.

To obtain a simple composite color image signal without causing color unevenness or hue shift since only one color signal is multiplexed even when a composite image signal is obtained with the configuration shown in FIGS. 5 and 6. I can do it. Moreover, one of the color image signals does not need to be specially processed as in the prior art, and a composite color image signal that does not look unsightly can be obtained regardless of the color image signals to be composited.

In the apparatuses shown in FIGS. 3 and 4, most of the recording signal processing circuit and reproduction signal processing circuit are omitted for the sake of simplicity. For example, circuits known from conventional VTRs, such as clamp circuits, automatic gain control circuits, clip circuits, automatic phase control circuits, etc., are omitted because they are not directly related to the present invention.

Furthermore, it goes without saying that the format of the color image signal and the recording method of the recording/reproducing apparatus to which the present invention is applied are not limited to those shown in the embodiments.

(Effects) As explained above, in the color image signal synthesis method of the present invention, only one color signal of two color image signals is appropriately multiplexed, so color unevenness, color shift, etc. do not occur as in the conventional method. There is no need for special operations when photographing color image signals to be synthesized, and a good synthesized color image signal can be obtained with a simple device and operation.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a VTR using a conventional compositing method, Fig. 2 is a diagram showing a state recorded on a magnetic tape by the VTR shown in Fig. 1, and Fig. 3 is a diagram showing one example of the compositing method of the present invention. FIG. 4 is a diagram showing a magnetic sheet recording/reproducing apparatus as an embodiment, FIG. 4 is a diagram showing a VTR as another embodiment of the present invention, FIG. 5 is a diagram showing another example of the synthesis method of the present invention, and FIG. Figures A to D are diagrams showing examples of input/output characteristics of the switching signal generation circuit. 28 is a color signal changeover switch, 63 is an adder,
64 is a differential amplifier, 65 is a stretch circuit, 94
95 is an adder, 95 is a mixer, 96 is a color signal switching switch, 97 is a level comparison circuit, and 98 is a switching signal generation circuit.

Claims (1)

[Claims] 1. A first luminance signal separated from the first color image signal and a second luminance signal separated from the second color image signal.
and the first color image signal separated from the first color image signal to obtain a composite brightness signal.
and a second color signal separated from the second color image signal are multiplexed onto the composite luminance signal to obtain a composite color image signal. . 2. Claims characterized in that either the first color signal or the second color signal is multiplexed into the composite brightness signal depending on the levels of the first and second brightness signals. 2. The method for synthesizing color image signals according to item 1. 3. Comparing the levels of the first luminance signal and the second luminance signal, and multiplexing the color signal separated from the color image signal corresponding to the luminance signal with the higher level onto the composite luminance signal. A method for synthesizing color image signals according to claim 2, characterized in that: 4 Multiplexing either the first color signal or the second color signal into the composite brightness signal only when the level difference between the first brightness signal and the second brightness signal is greater than or equal to a predetermined value. A color image signal synthesis method according to claim 2 or 3, characterized in that: