JPS58229B2 - Sen-Aid Kaizenhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION As a color imaging device, a color separation image of a subject is formed by a color separation filter, and this color separation image is captured by a single image pickup tube, and from this, a luminance signal and a color signal (carrier color There is a device that obtains a composite signal with

The present invention attempts to improve the sharpness of a luminance signal obtained from such an imaging device.

First, an example of a color separation filter will be explained with reference to FIG.

In FIG. 1, this filter has striped filter sections Ye, C, M, and W that transmit yellow light, cyan light, magenta light, and white light, respectively, and therefore:
Strives 5R2SG and sB indicate band-shaped parts that can transmit red light, green light, and blue light, respectively, and these stripes SR and SG are tilted by θ1 in opposite directions with respect to stripe SB. There is.

When this filter projects the color-separated image of the subject onto the photoelectric conversion surface of the image pickup tube, the electron beam is i-
1゜i+1. As shown in . . . , the stripes are arranged so as to scan in the array direction of the stripes corresponding to the stripe sB of the color separation image, but the second stripes 5R2SB and S
The pitches of G in the - direction corresponding to the scanning direction of this beam are mutually equal, and the width is 1/1 of the pitch.
It is now 2.

Further, the portions indicated by W that transmit substantially all color light and the portions indicated by diagonal lines that do not transmit substantially all color light are triangular and are sequentially arranged so as not to be adjacent to each other in the above-mentioned - direction.

Therefore, the parts marked R, B, and G pass only red, blue, and green colored light, respectively, and the parts marked RB, RG, and GB pass red and blue (i.e., magenta), red and green (i.e., yellow), and green. and blue (i.e., cyan) color light, respectively.

Note that d is the distance between positions corresponding to adjacent beam scanning positions.

In this case, if the effective scanning surface of the photoelectric conversion surface of the image pickup tube is, for example, 9 mm x 12 mm with a length-to-width ratio of 3:4, then the stripe image corresponding to the stripe SB is generated within this effective scanning surface. In order to form 186 lines, the above-mentioned pitch P should be 12 mm/186 on the photoelectric conversion surface.
That is, it is set to 64μ.

Further, if the number of effective scanning lines is 250, the above-mentioned distance d is converted to 9 mm/250, or 36 μ, on the photoelectric conversion surface. Therefore, in the above example, θ is selected to be about 30.6°.

Of course, the ratio of the length and width of the effective scanning surface is not 3:4 but, for example, 1:
2, the angle of inclination θ1 is also changed accordingly.

In the case of interlaced scanning, in the next field, the position corresponding to the beam scanning position is i-1, i in the figure.

i+1. It goes without saying that it will be between the positions shown.

For example, when the pitch P is selected as described above, the carrier frequency fc of each signal component is 3.58 MHz.

By color-separating the subject using such a filter, projecting the color-separated image onto the photoelectric conversion surface of the image pickup tube, and scanning it with an electron beam, each stripe 5R2SB and SG
Since the pitches in the - direction corresponding to the scanning direction of the electron beam are mutually equal, each color signal component of red, blue, and green is obtained as a signal converted into a carrier at the same carrier frequency. Since the directions of the inclinations are different from each other, the phase difference between adjacent horizontal scanning sections is.

The color signal components are different from each other.

That is, the composite signal Ei obtained from the image pickup tube in an arbitrary first horizontal scanning section is expressed as follows.

In this equation, since Ri+Bi+Gi is a luminance signal, it is denoted by Yi, and the mata R1C03(ωct
+……)=Ri, B15in(ωct+……)=Bi
, G1C03(ωct-...)=Gi, then Ri+
Since Bi+Gi is a color signal, it is denoted by Ci.

Here, α and β are the phase angles determined by the stripe inclination, α
R1αB and αG are the initial phase angles, and in the case of Fig. 1, α=
2/3π, β=0.

An example of the frequency spectrum of the signal Ei is shown in FIG.

Also, to explain this phase relationship using a vector diagram, the third
As shown in the original signal column of the figure, the phase of the red color signal component advances by 2/3π in the next horizontal interval compared to the previous horizontal interval, and the phase of the blue color signal component advances by 2/3π in the adjacent horizontal interval. The phase difference becomes zero, and the phase of the green color signal component in the next horizontal section is delayed by 2/3π with respect to the previous horizontal section.

Therefore, by performing appropriate phase shifts and arithmetic operations on the color signal components in three adjacent horizontal sections, the red, blue, and green color signal components Ri, Bi, and Gi can be separated.

A specific configuration for this purpose is shown in FIG. 4, for example.

That is, in the same figure, 11 is a subject, 12 is an image pickup tube, a main lens 13 is placed on the optical path between these, and the color separation filter 4 shown in FIG. 1 is placed at the imaging position. to form a color-separated image of the subject 11, and project this color-separated image onto the photoelectric conversion surface of the image pickup tube 12 using, for example, the field lens 15 and the relay lens 16, and from this, the above-mentioned composite signal is generated in the i+1th horizontal period. E1+1
get.

Note that in this example, fc is 5 MHz. The signal Ei+1 obtained in this way is supplied to a low-pass filter 21 with a band of, for example, 0 to 4 MHz to extract a luminance signal Yi+1, which is supplied to a delay line 22 and delayed by one horizontal period, so that the luminance signal is set in the violet+1st horizontal section. Obtain signal Yi.

Further, the signal Ei+1 from the image pickup tube 12 has a band of, for example, 4 to 4.
The color signal Ci is supplied to a 6MHz bandpass filter 24.
+1 is taken out and sequentially supplied to delay lines 25 and 26 which delay each one by one horizontal period, and in the i+1st horizontal period, the color signal Ci is obtained from the delay line 25, and the color signal C1-1 is obtained from the delay line 26. obtain.

Therefore, from the filter 24 and the delay lines 25 and 26, the color signals C1+1. C1 and C1-1 will be obtained simultaneously.

Among the color signals obtained simultaneously, the color signal Ci+1 is added through a phase shifter 31 that delays the phase by 2/3π, the color signal C1 is added as is, and the delayed color signal Ci is added through a phase shifter 32 that advances the phase by 2/3π. 37.

Therefore, the color signals Ci+1 . The phase relationship of each color signal component in Ci and C1-1 is as shown in the second column from the top of the third section, that is, the red color signal component Ri+
1. Ri and R1-1 are all in phase, and blue color signal components Bi+1. Bi and B1-1 have a phase difference of 2/3π from each other, and the green color signal component Gi+1. Gi and G
1-1 also have a phase difference of 2/3π.

Therefore, in the adder 37, the blue color signal components cancel each other out, and the green color signal components also cancel each other out, so the adder 37 outputs the red color signal components Ri+1, Ri and R1.
-1 addition signal is obtained.

Note that since these components Ri+1 and R1-1 are approximately equal to component Ri, this addition signal is 3Ri.

That is, it is the red color signal component 3Ri.

The red signal component 3Ri thus obtained undergoes envelope detection in a detection circuit 41 to obtain a red signal Rc.

Further, the color signals C1+1 . Ci and C1-1 are supplied to adder 38.

In this case, as shown in the third column from the top of FIG.
There is a double phase difference of /3π, and the blue color signal component Bi+1. Bi
and B1-1 are in phase with each other, and the green color signal component Gi+1. Since Gi and G1-1 have a phase difference of 2/3π, the adder 38 outputs the blue color signal component 3Bi.
is obtained.

These three blue color signal component peaks are envelope-detected by a detection circuit 42 to obtain a blue signal Bc.

Furthermore, through a phase shifter 33 that advances the phase of the color signal Ci+1 from the filter 24 by 2/3π, the color signal Ci from the delay line 25 is passed as is, and the color signal C1-1 from the delay line 26 is
The adders 3 through the phase shifters 34 that delay the phase by 2/3π
Supply to 9.

In this case, as shown in the bottom column of FIG. 3, the red color signal components Ri+1°Ri and R1-1 have a phase difference of 2/3π, and the blue color signal components Bi+1. Bi and B1-
1 have a phase difference of 2/3π from each other, but the green color signal component Gi+1. ．． Since Gi and G1-1 are in phase with each other, the adder 39 obtains a green color signal component 3Gi.

This green color signal component 3Gi undergoes envelope detection in a detection circuit 43 to obtain a green signal Gc.

In this case, the reason why the delay time of the delay line 22 is set to one horizontal period as the luminance signal Yi is that the three primary color signals Rc, Bc, and Gc are used as the color signal Ci+1. Since the luminance signal is obtained from Ci and C1-1, the three primary color signals Re,
This is to match the temporal correspondence with Bc and Gc.

Therefore, in a simple type, it is not necessary to do this, and in that case, the delay time of the delay line 22 should correspond only to the time delay of the color demodulation system, for example, 0.7 to 0.8μ.
It may be about seconds.

Incidentally, the image pickup tube 12 is considered to be an optical-to-electrical conversion means, but since its conversion characteristics are generally non-linear, it causes level unevenness in the luminance signal for the reasons described below.

That is, for the sake of simplicity, the image pickup tube 12 is shown in FIG.
is composed of an ideal image pickup tube 101 with no nonlinearity and a signal transmission circuit 102 with nonlinear input/output characteristics, and the nonlinear characteristics of the transmission circuit 102 are shown by the curve 103 in FIG. From the image pickup tube 101, a composite signal Eo of a luminance signal Yo not affected by non-linear characteristics and a chrominance signal Co is obtained, and this is transmitted to a transmission circuit 102 to combine a luminance signal Yi affected by non-linear characteristics and a chrominance signal Eo. It can be regarded as a composite signal Ei with the signal Ci.

However, in this case, when the color signal Co passes through the transmission circuit 102, the color signal Co is detected due to its non-linear characteristic 103.

At this time, since the color signal Co has all the color information, the detected signal is nothing but a luminance signal, and the luminance signal resulting from this detection effect is mixed into the original luminance signal Yo.

That is, the color signal Co is detected by the non-linear characteristic 103 to form a luminance signal, and this luminance signal and the original luminance signal Yo
A mixed signal of the luminance signal Yi is obtained as the luminance signal Yi.

If the stripe width of the color separation filter 14 is 1/2 of the pitch, as shown in FIG. However, in the case of the non-linear characteristic 103, the level of the luminance signal Yi in the signal Ei (shown by a dashed dotted line) is equal to the color signal Ci due to the detection effect.
1/2 of the peak-to-peak level of (as shown by the dotted line)
It will increase more than that.

This increase is the luminance signal component formed by detecting the color signal co, and as is clear from the figure, the increase increases as the level of the signal Eo increases, that is, when the subject 1
1 becomes larger as it becomes brighter, so as a result, the luminance signal Yi
This causes level unevenness, which appears as uneven brightness on the playback screen.

Further, when the non-linear characteristic of the transmission circuit 102 is shown by the curve 104, the level of the luminance signal Yi in the signal Ei decreases to less than 1/2 of the peak-to-peak level of the color signal Ci, and the decrease amount is The higher the brightness, the more
Similar brightness unevenness also occurs.

Therefore, in this example, when a circuit is provided to correct the level unevenness of the luminance signal Yi, this correction circuit is used for the color signal Ci.
Detects the level of the luminance signal Yi and uses the detection signal to
This is to correct the level of.

That is, the luminance signal Yi is supplied from the delay line 22 to the subtracting circuit 51, and the color signal Ci corresponding to the luminance signal Yi from the delay line 25 is supplied to the detection circuit 52, so that, for example, in response to the non-linear characteristic 103, a positive polarity signal is obtained. Obtain the detected signal.

In this case, since the color signal Ci is detected as it is, the detected signal is nothing but the luminance signal Yi (however, the band is rather narrow), and its level is proportional to the level of the color signal Ci.

Therefore, this brightness signal Yi is set to a predetermined level by an attenuator 53 and then supplied to a subtracter 51 to subtract the brightness signal Yi from the attenuator 53 from the brightness signal Yi from the delay line 22.

Therefore, as described above, the level of the luminance signal Yi from the delay line 22 becomes smaller as the level of the chrominance signal Ci increases, and on the other hand, the level of the luminance signal Yi from the attenuator 53 is proportional to the level of the chrominance signal Ci. A luminance signal Yi corrected to a constant level is obtained from the device 51 regardless of the level of the color signal Ci.

In this case, when the delay time of the delay line 22 corresponds to the time delay of the color demodulation system, the color signal Ci+1 from the filter 24 is supplied to the detection circuit 52 instead of the color signal Ci from the delay line 25. Good too.

The present invention aims to improve the sharpness of such a single-tube color imaging device, since the band of the luminance signal Yi is restricted and the sharpness tends to decrease.

Therefore, in the present invention, preshoot and overshoot are added to the luminance signal Yi to improve the sharpness.

That is, the three primary color signals Rc from the detection circuits 41, 42 and 43
, Bc and Gc are supplied to an adder 54 to obtain a luminance signal Yc.

In this case, since the band of the color signal Ci is relatively narrow, the band of the luminance signal Yc is also relatively narrow (see Fig. 2).If the luminance signal Yi is a rectangular wave as shown in Fig. 7A, for example, the luminance signal The signal Yc is a signal with gradual rises and falls, as shown by the solid line in FIG.

(In this case, the delay circuits 22, 25, and 26 cause the signal Yi
and Yc have a phase relationship as shown in FIG.
1 to subtract the luminance signal Yc from the luminance signal Yi.

Therefore, the subtracter 51 obtains a luminance signal Yw with preshoot and overshoot and improved sharpness in the horizontal direction, as shown in FIG.

Further, in this case, the luminance signal Yc is transmitted during three horizontal periods i+1.
Color signals C1-h, Ci and C1- at i and i-1
1, the sharpness in the vertical direction is improved as well as the sharpness in the horizontal force direction.

On the other hand, the photoelectric conversion surface and optical system of the image pickup tube 12 have the highest resolution at the center and are blurred at the periphery, resulting in a decrease in the sharpness of the three primary color signals and color shading.

Therefore, in this example, a circuit for correcting the three primary color signals is also provided.

That is, an arithmetic circuit 56 is provided, to which the three primary color signals Rc, Bc, and Gc from the detection circuits 41, 42, and 43 and the luminance signal Yw from the subtracter 51 are supplied, and the adder 54
The luminance signal Yc from is set to a predetermined level by an attenuator 57 and then supplied to the arithmetic circuit 56 to perform the following calculation.

In this case, the signals R2, Bc, Gc, and Yc have relatively narrow bands as described above, while the signal Yw has a wide band, but if the wide band three primary color signals are Rw, Bw, and Gw, then (
Rw+Bw+Gw=Yw), generally Rw=k·Rc, Bw=k·Bc, and Gw=k·Gc.

However, k is a coefficient that changes depending on the state of blur of the image of each part on the photoelectric conversion surface of the image pickup tube 12, and is 0≦≦1.

Therefore, when performing the above calculation in the calculation circuit 56,
Regardless of the value of K, the levels of the three primary color signals Bc, Bc, and Gc are constant, that is, the three primary color signals Rw, BW, and Gw have high resolution regardless of the state of blur.

Also, by setting the level to a constant level, color shading will not occur.

With the high resolution thus obtained.

That is, the broadband three primary color signals Rw, Bw and Gw are, for example, N
The signal is supplied to the TSC encoder 60.

This NTSC encoder 60 is configured as shown in FIG. 8, for example.

That is, the three primary color signals Rw, Bw, and color signals from the correction circuit 56 are supplied to an adder 61 and added to obtain a broadband luminance signal Yw, and this signal Yw and the blue signal Bw from the correction circuit 56 are supplied to a subtracter 62. The blue color difference signal Bw-Yw is obtained, and this is supplied to the balanced modulator 63 to obtain a balanced modulation signal based on the blue color difference signal, and the signal Yw from the adder 61 is
The red signal Rw from the correction circuit 56 is supplied to a subtracter 64 to obtain a red color difference signal Rw-Yw, which is then supplied to a balanced modulation circuit 65 so that the balanced modulation signal by the blue color difference signal has a phase of π. A balanced modulation signal using a red color difference signal shifted by /2 is obtained.

Then, each balanced modulation signal based on the blue and red color difference signals from the modulators 63 and 65 is supplied to an adder 66 and added to obtain a quadrature two-phase balanced modulation signal based on the red and blue color difference signals. The adder 61 supplies the brightness signal Yw, and the signal generator 67 supplies the vertical and horizontal synchronizing signals and the burst signal.
A color video signal based on the TSC system is obtained and taken out to an output terminal 68.

Alternatively, if the correction circuit 56 is not provided, the encoder 6
0 is configured as shown in FIG. 9, for example.

That is, in this case, 3 from the detection circuits 41, 42 and 43
The primary color signals Rc, Bc and Gc are supplied to an adder 61 to obtain a luminance signal Yc, and the subtracters 62 and 64 provide a signal Y.
c and the blue and red color difference signals Bc-Y from the signals Be and Bc.
c and Bc-Yc, and by supplying the broadband luminance signal Yw from the subtracter 51 to the adder 66, an NTSC color video signal is obtained at the terminal 68.

Thus, according to the present invention, a color video signal with improved sharpness can be obtained.

Moreover, the configuration for this purpose is extremely simple.

FIG. 10 shows a concrete connection example of the color demodulation system described above.

That is, the composite signal Ei+t obtained from the image pickup tube 12 is input from the input terminal 111→transistor 112→transistor 113.
The signal is supplied to the delay line 22 through the transistor 115 to be delayed by the time delay of the color demodulation system (or one horizontal period), and then supplied to the trap circuit 114 to remove the color signal Ci and obtain the luminance signal Yi. The signal is supplied to the transistor 116 of the subtraction circuit 51 through the terminal 117 to obtain a broadband luminance signal Yw.

Further, the signal Ei+t from the transistor 112 is supplied to the band-pass filter 24 to extract the color signal C1+1, and thereafter the signal processing described above is performed and the detection circuits 41, 42 and 4
3, the three primary color signals Re, Bc and Gc are obtained and sent to the terminal 124 through transistors 121, 122 and 123.
, 125 and 126.

Furthermore, the color signal C1+ is supplied from the filter 24 to the detection circuit 52 through the transistor 131.

The detection circuit 52 is bipolar so as to obtain positive and negative detection signals, that is, brightness signals Yi+1 and -Yi+i of positive polarity and negative polarity. A brightness signal of a predetermined level is obtained with positive or negative polarity, and this is transmitted to transistor 1.
32 to the transistor 116, and is added to or subtracted from the luminance signal Yi+t from the transistor 115 to correct level unevenness of the luminance signal Yi+1.

Further, a common load resistor 134 is connected to the collectors of the transistors 121, 122, and 123 to form an adder 54, where a luminance signal Yc is obtained, and this is transmitted to the transistor 1.
The brightness signal Yi+1 from the transistor 115 is supplied to the transistor 116 through the variable resistor 55 connected to the collector of the brightness signal Yi+1, thereby improving the sharpness of the brightness signal Yi+1 from the transistor 115.

In this case, the phase delay amount of the phase shifters 32 and 33 and the phase shifter 3
It is also possible to change the connection of the adders 37, 38 and 39 as shown in FIG. 11 by setting the phase advance amount of 1 and 34 to 1/3π.

Next, an example of the case where the present invention is applied to an imaging device using another pattern type as the filter 14,
Let's explain starting with the filter 14.

FIG. 12 shows the filter 14, and as shown in FIG. 13, two of the red, blue and green color signal components are obtained as carrier signals at the same carrier frequency. The other one is obtained as a carrier signal with a carrier frequency twice as high as the above carrier frequency, and for two color signal components with the same carrier frequency, the next horizontal interval is compared to the previous horizontal interval. The phase shifts are different from each other, and the phase differences between adjacent horizontal sections of the two color signal components are each different from π or an integer multiple thereof.

The example shown in FIG. 12 is a case in which red and blue color signal components are obtained at the same carrier frequency.

That is, in the example of FIG. 12, the stripes SR and sB extend in directions opposite to each other and inclined by θ6 with respect to the extending direction of the stripe sG.

For example, if the pitch P is selected as described above, the carrier frequency fc of the green color signal component will be 3.58 MHz for any filter, and the carrier frequency of each red and blue color signal component will be 1.79 MHz. become.

Moreover, since the inclination directions of the stripes SR and sB are different, the phase shift of the next horizontal section with respect to the previous horizontal section is different for the red and blue color signal components, and as is clear from the figure, the stripe The positional shift in the - direction corresponding to the beam scanning direction between the positions corresponding to the temporally adjacent scanning positions of the SR and SB beams is 4/3P in the example of Fig. 12. Since the pitch 2P in the − direction corresponding to the scanning direction of the beams of the second-order stripes SR and SB does not match half P or an integral multiple thereof, for the red and blue color signal components of the same carrier frequency, The phase difference between adjacent horizontal sections becomes different from π or an integral multiple thereof.

That is, in this case, the color signal component becomes a rectangular wave signal and contains only odd harmonic components, and the second harmonics of the red and blue color signal components do not mix into the green color signal component.
A composite signal Ei obtained from the image pickup tube in an arbitrary i-th horizontal scanning section is expressed as.

In this equation, Ri+Bi+Gi is a color signal, of which Ri+j3i is indicated by Ci.

As shown in the original signal column of Figure 14, the phase of the red color signal component in the next horizontal section is 4/3π ahead of the previous horizontal section, and the phase of the blue color signal component is advanced by 4/3π in the next horizontal section. The phase is delayed by 4/3π.

Therefore, the green color signal component Gi can be separated in terms of frequency, and the remaining red and green color signal components Ri and Bi can be delayed by signal delay operation using the phase difference between each horizontal scanning section. Separation can be achieved by applying appropriate phase shifts and arithmetic operations.

A specific configuration for this purpose is shown in FIG. 15, for example.

That is, the signal Ei-h is supplied to the low-pass filter 21 to take out the luminance signal Yi+1, which is supplied to the delay line 22 and delayed by one horizontal period to obtain the luminance signal Yi in the i+1th horizontal period.

Further, the signal Ei+1 from the image pickup tube 12 is supplied to the bandpass filter 23 to extract the green color signal component Gi+1, and is supplied to the delay line 27 which delays it by one horizontal period to obtain i +
During the first horizontal period, a green color signal component Gi is obtained, which is supplied to a detection circuit 43 for envelope detection to obtain a green signal Gc.

Further, the signal Ei+1 from the image pickup tube 12 is supplied to the bandpass filter 24 to extract the color signal Gi+t, which is sequentially supplied to the delay lines 25 and 26 which delay each one by one horizontal period. From is the color signal C
i is obtained, and a color signal C1-1 is obtained from the delay line 26.

Therefore, the color signals Gi+1, Ci and C1-1 are obtained simultaneously from the filter 24 and the delay lines 25 and 26.

Among the color signals obtained simultaneously in this way, the color signal Ci+1 is added through a phase shifter 31 that delays the phase by 4/3, the color signal Ci is added as is, and the color signal C1-1 is added through a phase shifter 32 that advances the phase by 4/3π. 37.

Therefore, the color signals Ci+1 . The phase relationship between the red and blue color signal components in Ci and C1-1 is the first
As shown in the middle column of Figure 8, the red color signal component Ri
+1. Ri and R1-1 are all in phase, and blue color signal components Bi+1. Bi and B1-1 have a phase difference of 2/3π.

Therefore, since the blue color signal components cancel each other out in the adder 37, the adder 37 outputs a sum signal of the red color signal component Ri+1°Ri and Ri+t (this is equivalent to the signal component Ri, henceforth the red color signal component Ri ) is obtained.

The red color signal component Ri thus obtained is subjected to envelope detection in a detection circuit 41 to obtain a red signal Rc.

Further, among the color signals obtained simultaneously from the filter 24 and the delay lines 25 and 26, the color signal C1+1 is phase-advanced by 4/3π. The signals are supplied to an adder 38 through a phase shifter 36 that delays the phase.

In this case, as shown in the lower column of FIG. 18, red color signal components Ri+1. Ri and R1-1 have a phase difference of 2/3π, and the blue color signal component Bi+1. Since Bi and B1-1 are in phase with each other, the adder 38 obtains the blue color signal component Bi.

This blue color signal component Bi undergoes envelope detection in a detection circuit 42 to obtain a blue signal BC.

In this example, as a circuit for correcting the level unevenness of the luminance signal, the color signal Ci corresponding to the luminance signal Yi is supplied from the delay line 25 to the detection circuit 52, and the non-linear characteristic 10 is
3, a positive detection signal is obtained, and the level unevenness of the luminance signal Yi is corrected in the same manner.

As described above, according to the present invention, a color video signal with improved sharpness can be obtained, and the configuration thereof is very simple.

In the above case, a television camera is constructed, but the color separation images obtained are captured on a black and white photographic film, and after the captured film is subjected to necessary processing such as developing, fixing and printing, it is transferred to a naked image tube. 12, a color-separated image is projected onto the image pickup tube 12, and therefore a color image signal can be obtained in the same way.

It is also possible to record the composite signal Ei on a film or the like by electron beam recording, and to reproduce the recorded film or its print film using a dedicated player.

Alternatively, a hologram can be used to perform something similar to so-called selector vision.

[Brief explanation of the drawing]

Figure 1 is a diagram of an example of a color separation filter, Figure 2 is a diagram showing the frequency spectrum of a signal obtained by this, Figure 3 is a spectrum diagram for explaining the signal, and Figure 4 is an example of a demodulation circuit. The system diagram, Figures 5 and 6 are diagrams for explaining the nonlinearity of the image pickup tube, Figure 7 is a waveform diagram for explaining sharpness, and Figures 8 and 9 are diagrams for explaining the NTSC encoder. An example system diagram, FIGS. 10 and 11 are connection diagrams of other examples of the demodulation circuit, and FIG. 12 is a diagram of another example of the color separation filter.
FIG. 13 is a frequency spectrum diagram of the signal obtained thereby, FIG. 14 is a vector diagram for explaining the signal, and FIG. 15 is a system diagram of another example of the demodulation circuit. 11 is a subject, 12 is an image pickup tube, 14 is a color separation filter,
21 is a low pass filter, 24 is a band pass filter, 2
5 and 26 are delay lines that delay one horizontal period, 31 to 34
is a phase shifter, 37 to 39 and 54 are adders, 41 to 43 and 52 are detection circuits, 51 is a subtracter, 53.55 and 57
is an attenuator, 56 is an arithmetic circuit, 60 is an NTSC encoder, and 68 is an output terminal.

Claims (1)

[Claims] 1. Obtain a luminance signal and a carrier color signal from an image pickup tube, demodulate the color signal using the carrier color signal of a horizontal scanning amount adjacent to each other, obtain a composite luminance signal from the demodulated color signal, and A method for improving sharpness, wherein a composite brightness signal obtained from the signals is set to a predetermined level, and then added to or subtracted from the brightness signal from the image pickup tube to improve the sharpness of the brightness signal.