JPH0683430B2 - Image playback device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reproducing apparatus capable of directly or indirectly reproducing an output signal from an image pickup apparatus capable of special exposure as an image.

[0002]

2. Description of the Related Art In a video camera, the amount of incident light is automatically controlled by an auto iris or the like, but there is still a problem in the responsiveness of the servo loop and the mechanical responsiveness. When a solid-state image pickup device is used as the image sensor inside, the level of the video signal largely fluctuates with respect to the exposure error because the dynamic range is extremely narrow.

[0003]

By the way, in the case of continuous shooting such as movie shooting, the rise time can be expected enough, so such a problem is relatively small, but only one frame is required as in still shooting. When shooting, the rise of the exposure control system becomes a big problem, and therefore the error cannot be ignored, and it is difficult to correct such a large error by the AGC circuit generally provided in the video camera. Is.

In the case of a camera, the exposure is corrected by taking a special effect (for example, backlight compensation) at the time of photographing. When such an intentional exposure change occurs, the above-mentioned situation is encountered. There is a drawback in that the image signal obtained in the case of unintentional exposure deviation is at the same level, and the image reproducing device such as a printer or an image monitor cannot judge this.

Therefore, the operator must manually adjust the level while monitoring the reproduced image, but this is extremely inconvenient, and since the reproducing machine cannot distinguish the two, AGC is simply applied. It also has the drawback that it cannot

It is an object of the present invention to solve the above-mentioned drawbacks of the prior art and to provide an image reproducing apparatus capable of always performing appropriate exposure correction on a video signal output from an image pickup apparatus.

[0007]

An image reproducing apparatus of the present invention comprises a separating means for separating an instruction signal from an image signal in which an instruction signal relating to an exposure level control state of the image signal is multiplexed, and a separating means for separating the instruction signal. And an exposure level control means for controlling and outputting the exposure level of the image signal according to the designated instruction signal.

[0008]

According to the above construction, the drawbacks of the prior art can be solved, and proper exposure correction can always be applied to the video signal output from the image pickup device.

[0009]

The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a view showing an example of the arrangement of an image pickup apparatus according to the present invention. In this embodiment, exposure control information such as backlight compensation and AE lock is superposed on a video signal.

Light incident through the diaphragm 1 is converted into an electric signal in an image pickup device 2 such as an image pickup tube or a solid-state image pickup device, scanned by a scanning control circuit 3 and output as a time-series electric signal. .

The output from the image pickup device 2 is AE
The (Auto Exposure) control circuit 4 performs integration or the like at a predetermined cycle, and is used for feedback control of the diaphragm 1. By this, auto iris control is performed so that a constant light amount is always incident on the imaging device 2. There is.

On the other hand, the output of the image pickup device 2 is controlled by the AGC circuit 5 so as to have a constant level, and then converted into a signal suitable for recording or transmission in the signal processing circuit 6.

Reference numeral 7 is a mode instruction circuit, which supplies an instruction signal to the AE control circuit 4 and the like so as to switch the reference level of the AE according to ON / OFF of the switches 8 and 9.

The switch 8 is, for example, turned on at the time of backlight correction and is a switch for slightly raising the reference level of the AE, and the switch 9 is a switch for slightly darkening the screen, for example, at dusk or in a tunnel. Then, when the switch 9 is turned on, the reference level of the AE is set to be slightly lowered.

The output of the mode instruction circuit 7 is ID (Iden
The signal formation circuit 10 is supplied to
Forming an ID signal as an instruction signal for instructing the exposure state represented by ON / OFF of the switches 8 and 9,
This is superimposed on the output signal of the signal processing circuit 6 in the adder circuit 11, and the output is supplied to a recording device, a reproducing device, a transmitting device, or the like.

As the ID signal, a method in which a predetermined coded pulse is superimposed within the vertical blanking period of the video signal, or a low-frequency pulse whose 4H (horizontal period) is 1 bit is video. A method of superimposing it on the signal can be considered.

FIG. 2 is a diagram showing an example of the structure of the reproducing apparatus.
A video signal including an ID signal input from an external input terminal or a reproducing head is separated into a video signal and an ID signal by the ID separation circuit 12, and the ID signal is input to the determination circuit 13.

On the other hand, the video signal is level-adjusted via the AGC circuit 14, and then converted into a signal suitable for the video monitor 16 or a signal suitable for the printer 17 in the reproduction signal processing circuit 15.

Reference numeral 18 denotes a changeover switch for changing over and outputting the signal output from the reproduction signal processing circuit 15 to the video monitor 16 or the printer 17.

The gain or level in the AGC circuit 14 is controlled according to the output of the discriminating circuit 13.

With this configuration, even if the exposure level is changed for the purpose of achieving a special effect when AE control is performed, this information is superposed on the video signal as an ID signal and output, so that it is reproduced on the reproducing side. The level of the input video signal can be automatically adjusted based on this ID signal.

FIG. 3 is a diagram showing a concrete configuration example of the mode instructing circuit 7 and the ID signal forming circuit 10 in FIG.

Reference numerals 19 and 20 are resistors, 21 is an exclusive OR gate, 22 and 23 are AND gates, 24 is a ring counter, and the horizontal synchronizing signal Hd is input to the ring counter 24 as a clock. A second output Qn and a (n + 1) th output Qn + 1 are supplied to the AND gates 22 and 23, respectively.

The ring counter 24 is reset by the vertical synchronizing signal Vd and returns to "0" so that the horizontal scanning line segment of one field can be counted.

Note that n and (n + 1) respectively correspond to two predetermined horizontal scanning line addresses within the vertical blanking period, and these addresses are, for example, within the blanking period preceding the video signal in time. It is desirable that it is after the equalization pulse.

Since the configuration is as shown in the figure, Qn and Qn + 1 are respectively "1" and "0" in the 2H period at a predetermined timing of the vertical blanking period on the front side of the video signal of one field, and subsequently, Qn, Q during the next 1H period
n + 1 is "0" and "1", respectively.

When Qn is "1", the information of the switch 8 is read, and when Qn + 1 is "1", the information of the switch 9 is read.

The ON / OFF information of the switches 8 and 9 is added to the video signal by the adder 11 as a 2-bit ID signal.

The exclusive OR gate 21 is for eliminating the state where both the switches 8 and 9 are turned on.

FIG. 4 is a diagram showing an example of the configuration of the AE control circuit 4. The output from the image pickup device 2 is supplied to an integrating circuit 25 which performs integration at a predetermined cycle and is used as photometric information.

The photoelectric information input to the integrating circuit 25 may be the output of a photometric sensor provided separately from the image pickup device 2.

Reference numeral 26 is a frequency dividing circuit which divides the vertical synchronizing pulse Vd, for example, to form a reset signal for the integrating circuit 25.
The output of the integrating circuit 25 is input to the differential amplifier 26 and compared with the reference voltage Vref.
Supply to.

The driver 27 drives the diaphragm 1 by increasing the differential output.

Further, the input of the differential amplifier 26 can be switched and connected to the manual aperture value setting circuit 33 side by the auto / manual switch 32.

Reference numeral 34 is a potentiometer which works in conjunction with an aperture value setting dial (not shown).

Therefore, the automatic / manual selector switch 3
When 2 is switched to the a side, automatic exposure control is performed based on the output of the integrating circuit 25, and when it is switched to the b side, manual aperture control based on the aperture value setting dial is possible.

On the other hand, in the present embodiment, the reference voltage Vref of the differential amplifier 26 is variable, and there are three kinds of voltages: a reference voltage V1 slightly higher than the reference voltage V2 in the standard mode and a voltage V3 slightly lower than the reference voltage V2. It is possible to switch with and.

Reference numeral 28 is a constant voltage source, and 29 to 31 are analog switches (ASW) for selectively introducing these voltages V1 to V3 to the differential amplifier 26, respectively, by gates 35 to 37, respectively. Controlled.

A switch 8 is provided to each of the gates 35 to 37,
The output of 9 is input, and switches 8 and 9 are (0,
At the time of 0), only the analog switch 30 is opened and (1,
At the time of 0), only the analog switch 29 is opened and (0,
In the case of 1), the logic circuit is formed so that only the analog switch 31 is opened.

Since it is constructed in this way, the switch 8
When is ON, diaphragm 1 opens more than standard level,
On the contrary, when the switch 9 is ON, the diaphragm 1 is closed more than the standard level.

Therefore, the level of the video signal is increased or decreased from the standard level depending on the case, but since the increase / decrease information is superimposed on the video signal as the ID signal,
At the time of reproduction, the reproduction can be performed without canceling the increase or decrease in the level of this video information.

FIG. 5 is a diagram showing an example of such a gain control method on the reproducing side, and the same numbers as those in FIG. 2 indicate the same elements.

In the figure, 38 is the ring counter 24 shown in FIG.
A ring counter having the same function as the vertical sync signal V
The horizontal synchronizing signal Hd is reset by d and counts the horizontal synchronizing signal at the same timing as the ring counter 24, that is, the nth and (n + 1) th horizontal synchronizing signals after vertical synchronization are extracted by the gates 39 and 40.

41 and 42 are RS flip-flops (R) set by the high level outputs of the gates 39 and 40.
-SFF) and is reset by the vertical synchronizing signal Vd.

The Q output of the R-SFFs 41 and 42 is the gate 4
3 to 45 and three potential levels V1, V2, and V3 (V1 <V2 <formed by the constant voltage source 46).
Analog switch (AS) to select one of V3)
W) Control 47-49.

Reference numeral 50 is a transistor such as an FET whose gate is controlled by this voltage, and the impedance changes depending on the voltage level of the gate.

Reference numeral 55 is also a transistor such as FET having the same variable impedance function as the transistor 50.

Reference numerals 51 and 52 denote voltage dividing resistors, and these resistors 51 and 52 and the transistors 50 and 55 cause
Input level can be controlled.

Reference numeral 53 is an amplifier, the output of which is rectified by a low-pass filter (LPF) 54 to control the gate of the transistor 55 by negative feedback. Therefore, the circuits 51 to 55
Form an AGC circuit.

In the present embodiment, the transistor 50 is further provided to control the input level to the AGC circuit.

The output of the amplifier 53 is guided to the reproduction processing circuit 15 described above.

With this configuration, the transistor 50 is used when the AE control is performed based on the normal reference level during image pickup, that is, when the outputs of the gates 39 and 40 are "0" and "0", respectively. A voltage V2 is applied to the gate of the gate, and the impedance becomes a predetermined impedance (Z2).

When the AE level is raised for the purpose of backlight compensation during image pickup, that is, when the gates 39 and 40 are "1" and "0", respectively, the voltage of the gate of the transistor 50 is lower than the voltage V2. The voltage V1 is applied, the impedance Z1 of the transistor 50 becomes higher than Z2, the level of the signal input to the amplifier 53 increases slightly, and the reproduced image becomes bright.

On the contrary, when the reference level of the AE is lowered at the time of image pickup, that is, when the gates 39 and 40 are "0" and "1", respectively, the voltage V3 higher than the voltage V2 is applied to the gate of the transistor 50. As a result, the impedance Z3 of the transistor 50 becomes lower than Z2, the input signal level of the amplifier 53 is slightly decreased, and the reproduced image becomes dark.

In the embodiment, the AE at the time of image pickup and the reference level of the AGC on the reproducing side can be switched in three steps.
Needless to say, the switching may be performed in more stages or continuously.

In the embodiment, on the reproducing side, for example, 3
Although two different AGC levels are selected, when the normal AE level is picked up on the image pickup side, the AG on the playback side is selected.
When C is operated and the AE level is raised or lowered with respect to the standard level on the imaging side, the AGC on the reproducing side may be disabled.

Further, although the reference voltage of the differential amplifier on the image pickup side is changed in the embodiment, what kind of signal may be used if the level of the signal for controlling the diaphragm is changed? But good.

Further, as described above, the ID signal may be superimposed on the video signal in any form.

Further, in the present embodiment, the level control of the video signal is performed in relation to the reproducing side AGC circuit.
The gain may be adjusted according to the ID signal or the signal attenuation rate may be controlled by an attenuator or an amplifier which is completely different from the C circuit.

Next, FIG. 6 is a diagram showing another embodiment of the present invention. In this embodiment, the AE lock switch 56 is turned on and off.
F is superposed on the video signal as an ID signal, whereby the diaphragm is fixed, and the level fluctuation of the video signal during that time is reproduced as it is.

That is, as shown in FIG. 7, in the regenerator, the output of the ID separation circuit 12 is discriminated by the discrimination circuit 13, and when the AE lock is applied, the gain of the amplifier 57 in the feedback loop of the AGC circuit is attenuated or zero. I am trying to

As a result, when the AE is locked, the playback side A
The GC does not work at all, or the shooting effect intended on the imaging side is not canceled, and when the feedback amount is attenuated, a slight level fluctuation is suppressed.

In the embodiment of FIG. 5, since the entire input level to the AGC circuit 14 is changed, the AGC circuit 1
4 may correct the intentional variation of the input level, but the configuration shown in FIG. 7 only changes the way the AGC works, so the problem of the configuration in FIG. 5 does not occur.

FIG. 8 is a view for explaining another embodiment of the present invention, which is effective when the response and accuracy of the aperture control are uneven.

That is, the brightness of the image is detected by the photometric element in advance before the main image pickup, and the aperture value is determined by the photometric circuit 59. The aperture value is set to this aperture value or the aperture value of the manual aperture value setting circuit 33. It is controlled based on

Reference numeral 60 is a switch for switching the both.

However, since the responsiveness of the aperture is extremely low compared to the image pickup time, the actual aperture state at the time of image pickup includes some error with respect to the set value in the manual aperture value setting circuit 33 or the photometric circuit 59. There is a thing.

When reading the signal of the imaged image, the actual exposure level is detected by measuring the average level or integration level of this signal by the photometric circuit 61, and this level and the manual or AE before imaging are detected. By comparing with the comparator 62 the set level by
An error signal is formed, and the error signal is formed by the ID signal forming circuit 1
It is also possible to correct the aperture error on the reproducing side by converting the ID signal at 0 and superimposing it on the video signal obtained through the signal processing circuit 6.

In this case, although the circuit configuration on the reproducing side is not shown, the gain of the AGC circuit, the input signal level, the feedback amount or the like may be adjusted according to the ID signal during reproduction.

FIG. 9 is a simplified configuration of the embodiment of FIG. 8 described above. In still photography in which the responsiveness of the aperture is a particular problem, the gain on the reproducing side is increased by a predetermined amount. Alternatively, the number is reduced.

That is, when the still mode and the movie mode are set to be switched for image pickup, the switch 63 is switched to selectively superimpose the output of the still ID signal generator 64 or the movie ID generator 65 on the video signal.

On the reproducing side, if this ID signal is discriminated and it is a still ID signal, the gain of the amplifier 66 provided in front of the AGC circuit 14 is increased or decreased by a predetermined amount.

This method is based on the premise that the aperture is fully closed or fully opened in the initial state before photographing.
For example, when starting from the fully closed state, the aperture errors at the time of capturing the image of the device 2 are averaged over all apertures, and the gain of the amplifier 66 is increased by an amount corresponding to this average aperture error. On the contrary, when the diaphragm is fully opened, the gain of the amplifier 66 is decreased by an amount corresponding to the average diaphragm error.

In this case, since the error corresponding to each aperture value can be experimentally obtained, the aperture value data or the error data at the aperture value may be superposed as an ID signal on the video signal. Well, by doing so, it is possible to more accurately correct the aperture error.

As described above, according to the present embodiment, even when the exposure level is raised or lowered with respect to the standard level for the purpose of obtaining a special effect during image pickup, this effect is canceled by the AGC circuit on the reproducing side. If the exposure is fixed, such as AE lock, the function of the AGC circuit on the reproducing side is reduced or cut so that the change in the image level at the time of image capturing can be reproduced as it is.

Further, according to this embodiment, the actual aperture state is compared with the set aperture, the ID signal corresponding to the error is superimposed, and the error is corrected based on the ID signal during reproduction. Therefore, regardless of the responsiveness of the aperture, a screen with the desired brightness can always be obtained, and the AGC on the imaging side is correspondingly increased.
The circuit can be simplified and the device can be downsized.

Further, according to the present embodiment, in the case of the still image pickup, the ID signal is instructed to increase or decrease the gain on the reproducing side by a predetermined amount. The gain adjustment circuit is simplified.

[0079]

As described above, according to the present invention, there is provided an image reproducing apparatus which solves the drawbacks of the prior art and can always perform proper exposure correction on a video signal output from an image pickup apparatus. You will be able to do it.

[Brief description of drawings]

FIG. 1 is a diagram showing a first configuration example of an image pickup apparatus of the present invention.

FIG. 2 is a diagram showing a first configuration example of an image reproducing device.

FIG. 3 is a diagram showing a configuration example of a mode instruction circuit and an ID signal forming circuit in FIG.

4 is a diagram showing a configuration example of an AE control circuit in FIG.

5 is an ID separation circuit, a discrimination circuit and an AG in FIG.
It is a figure which shows the structural example of C circuit.

FIG. 6 is a diagram showing a second configuration example of the image pickup apparatus of the present invention.

FIG. 7 is a diagram showing a second configuration example of the image reproducing apparatus of the present invention.

FIG. 8 is a diagram showing a third embodiment of the image pickup apparatus of the present invention.

FIG. 9 is a diagram showing another embodiment of the image pickup apparatus and the image reproducing apparatus of the present invention.

[Explanation of symbols]

 1 Aperture 2 Imaging Device 7 Mode Instructing Circuit 8 Switch for Exposure Increase 9 Switch for Exposure Decrease 10 ID Signal Forming Circuit

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location H04N 5/91 H 4227-5C L 4227-5C

Claims (1)

[Claims] 1. A separating means for separating an instruction signal from an image signal in which an instruction signal relating to an exposure level control state of the image signal is multiplexed, and the exposure of the image signal according to the instruction signal separated by the separating means. An image reproducing apparatus having an exposure level control means for controlling and outputting a level.