JPH09149311A - Imaging device - Google Patents

Abstract

(57) An object of the present invention is to improve the usability by making it possible to easily change the angle of view in an imaging device having an auto-zoom function that automatically controls the size of a subject to be constant. SOLUTION: In an image pickup apparatus having an auto-zoom function, a subject extracting means 6 for outputting a feature amount of a subject,
Control means 7 for automatically controlling the zoom magnification so that the size of the subject outputted by the subject extracting means becomes substantially equal to a predetermined reference value, and zoom buttons 12b, 12c for manually changing the zoom magnification of the zoom lens 1. A detection means 7 for detecting this zoom button input, a memory means 10 for storing a reference value, and a memory control means 11 for changing the reference value are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus, and more particularly to an image pickup apparatus having an auto zoom function for automatically performing zoom control.

[0002]

2. Description of the Related Art With the widespread use of image pickup devices represented by video cameras and movies, research and development relating to automation of camera operations have been actively conducted. As these automatic functions, auto iris, auto white balance, auto focus, etc. have been put to practical use. Also,
Even if the subject moves away or approaches, the zoom operation that was performed manually in the conventional imaging device is automated.
An auto-zoom function that keeps the angle of view constant has been proposed.
For example, in the device disclosed in Japanese Patent Laid-Open No. 7-154665, a zoom lens is controlled so as to detect a subject from a video signal and keep the size of the subject constant.

[0003]

By the way, there is a case where it is desired to manually perform a zoom operation to change the angle of view during shooting, but in the conventional apparatus, a method of changing the angle of view during the operation of the auto zoom is performed. Did not consider. Therefore, when changing the angle of view during the auto zoom operation, it is necessary to stop the auto zoom once, reset the angle of view, and then operate the auto zoom again, which is not convenient. .

An object of the present invention is to solve such a problem and to easily reset the angle of view even during the automatic zoom operation in an image pickup apparatus having an automatic zoom function for automatically making the size of a subject constant. An object of the present invention is to provide an image pickup device capable of performing.

[0005]

In order to achieve the above object, according to the present invention, a zoom lens, an imaging means for converting an optical image formed by the zoom lens into a video signal, and a subject portion extracted from the video signal. Then, the subject extraction unit that outputs the feature amount of the subject such as the size of the extracted subject, and the zoom magnification is automatically controlled so that the size of the subject output by the subject extraction unit becomes substantially equal to a predetermined reference value. Control means, a zoom button for manually changing the zoom magnification of the zoom lens, detection means for detecting this zoom button input, memory means for storing a reference value,
The image pickup device is configured by the memory control unit that changes the reference value.

The auto-zoom function is started by the input of the auto-zoom button, and controls the zoom lens so that the size of the subject detected by the subject extracting means is kept constant. At this time, it is possible to maintain a constant angle of view by storing the size of the subject at the start of auto-zoom as a reference value and comparing it with the detected size of the subject.

When the zoom button (tele button or wide button) for manual adjustment is operated during the automatic zoom operation, the detecting means detects the input of the zoom button for manual adjustment and automatically controls the zoom lens by the automatic zoom. Cancel temporarily and accept manual operation. Thereby, the operator can set the subject to an arbitrary angle of view by operating the zoom button for manual adjustment. When the operation using the zoom button for manual adjustment is completed, the detection means detects that the button input has been completed. At this time,
The memory control unit uses the size of the subject detected by the subject extraction unit as a new reference value. Then, after the change of the reference value is completed, the operation of the auto zoom is automatically started.

With the above operation, it is detected that the angle of view has been changed by the zoom button for manual adjustment, and after the reference value is changed, the control of the auto zoom is restarted. The angle of view in can be easily reset and the usability is improved.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Each embodiment of the present invention will be described below. FIG. 1 is a block diagram showing the arrangement of an image pickup apparatus according to the first embodiment of the present invention. In the figure, 1
Is a zoom lens, 2 is a CCD (Charge Coupled Devic)
e) image sensor such as 3) A / D (analog / digital) conversion circuit, 4 signal processing circuit, 5 D / A (digital / analog) conversion circuit, 6 subject extraction circuit, 7 zoom control circuit , 8 is a zoom motor for driving the zoom lens 1, 9 is an output terminal, 10 is a memory, and 11 is a memory control circuit. 12 is an operation button,
It has three buttons, an auto-zoom button 12a for switching on / off the auto-zoom function, a tele (T) button 12b for zooming up, and a wide (W) button 12c for zooming down.

The optical image formed on the light receiving surface of the image pickup device 2 is photoelectrically converted by the zoom lens 1, and an analog image pickup signal is output. The signal processing circuit 4 includes the A / D conversion circuit 3
Then, a luminance signal and a color difference signal are generated from the image sensor signal converted into a digital signal in step 1, and known signal processing such as gamma correction and white balance correction is added to generate a video signal. This output video signal is converted into an analog signal by the D / A conversion circuit 5 and output from the output terminal 9.
The subject extraction circuit 6 is a circuit for extracting a subject portion from a video signal, further obtains a feature amount such as the area of the extracted subject portion, and outputs the value. The feature amount of the subject is calculated for each screen, that is, for each field or frame in the television signal. The memory 10 holds a reference value for automatic zoom control, and the memory control circuit 11 controls writing and reading of the reference value. The zoom control circuit 7 compares the area of the subject output from the subject extraction circuit 6 with the reference value output from the memory 10 to calculate a zoom magnification at which the area of the subject becomes substantially equal to the reference value, and the zoom motor 8 Is driven to feedback control the zoom lens 1. The zoom control circuit 7 may be composed of a microcomputer.

The operation of the subject extraction circuit 6 will be described in more detail. 2 is a block diagram showing the configuration of the subject extraction circuit 6 of FIG. 1, in which 20 is a binarization circuit, 21 is a comparison circuit, 22 is a region growing circuit, 23 is a memory, 24 is a feature amount calculation circuit, Reference numeral 25 is a sampling circuit, and 26 is an extraction condition setting circuit.

The subject extraction circuit 6 includes a signal processing circuit 4
The subject is extracted using the luminance signal and the color difference signal output from (FIG. 1). The input video signal from the signal processing circuit 4 to the subject extraction circuit 6 is a luminance signal Y and two types of color difference signals C _R ,
It is a signal containing C _B (collectively represented as C). The binarization circuit 20 extracts a subject from these Y and C signals as follows.

The subject generally has a brightness and chromaticity different from those of the background portion. Therefore, a portion that satisfies the conditions of constant luminance and chromaticity is extracted as a subject. For example,
When a person is set as the tracking target, the flesh-colored portion may be extracted. If the luminance Y and the chromaticity C ′ of the skin color of the person's face are in a region satisfying the following expression: Y _L <Y <Y _H …… Equation C _L ′ <C ′ <C _H ′ ... The conversion circuit 20
， High level is output for the input that satisfies the condition of the expression, and low level is output when it is not satisfied. That is, the high level is output only in the subject part.
Value. , A constant Y that sets the extraction condition in the formula
_The extraction condition setting circuit 26 sets _L , Y _H , C _L ′, and C _H ′ based on the sampling values of the Y and C signals output by the sampling circuit 25. For example, the value obtained by adding or subtracting the variance obtained by multiplying the average of the sampled values by a certain constant may be set. The sampling and extraction conditions are set according to the control signal output from the zoom control circuit 7. Normally, the extraction condition is set when the auto zoom button is input. The region thus binarized and extracted is called an extraction candidate region.

The comparison circuit 21 compares the extraction candidate area with the subject area already recorded in the memory 23 to generate a new area signal. Normally, the comparison circuit 21 may be configured by an AND circuit that obtains a logical product, and therefore outputs a signal that becomes high level only in the common portion of the extraction candidate area and the subject area.

The region growing circuit 22 is a circuit for expanding the region output by the comparing circuit 21 once. In order to do this, as an output of a certain pixel, the logical sum of the pixel and the input signal corresponding to the peripheral pixel may be taken as the output signal. Such enlargement processing and its hardware configuration are described, for example, on page 50 of "Industrial image processing".

The output of the region growing circuit 22 is recorded in the memory 23 as a new subject region. Feature quantity calculation circuit 2
Reference numeral 4 obtains characteristics such as the center of gravity and area of the subject area, and outputs them to the zoom control circuit 7 (FIG. 1). These series of operations are
It is repeated every field or every frame in the video signal.

The operation of the subject extraction processing described above will be described by taking the case where the image shown in FIG. 3A is input as an example. As shown in FIG. 3A, it is assumed that there are two persons on the screen and that the person at the center of the screen is desired to be tracked.
In the binarization circuit 20, when the extraction condition is set to extract the skin color part and the face of the person is extracted, the output image of the binarization circuit 20 is as shown in FIG. Is extracted. If the extraction of the person at the center of the screen has already started, the area growth circuit 22 is stored in the memory 23.
An image as shown in (d) of FIG. However, at this time, the movement of the person can be ignored. The input of the comparison circuit 21 is the two images of (d) of FIG. 3 and (c) of FIG. 3, and the output thereof is the image shown in (c) of FIG. .

By the above operation, the target subject can be extracted. In the above explanation,
Although the movement of the subject can be ignored, even if there is movement, extraction can be performed by the same operation as long as the extraction candidate region and the subject region output from the memory 23 overlap. It is necessary to give an initial value of the subject area to the memory 23 when starting the extraction, but for example, an appropriate small area may be given to the center of the screen.

The zoom operation method in the first embodiment will be described below. FIG. 4 is a diagram showing a control flow of the auto zoom. First, the auto zoom button 12
When the user presses a, the zoom control circuit 7 determines the button input (step S1) to enter the automatic zoom mode. Now, for example, the object in the center of the screen is regarded as a subject, and the subject extraction conditions are automatically set to set the subject (step S2), and the size of the subject output from the subject extraction circuit 6 is written in the memory 10. Thus, the reference value is set (step S3). Hereinafter, the auto-zoom control is performed by the above method (step S4), and even if the subject moves away or approaches, it is possible to automatically shoot in a certain size.

The angle of view is changed during auto-zoom as follows. When it is desired to change the size of the subject during the operation of the auto zoom, the tele button 12b and the wide button 12c are used as in the case of the manual zoom.
If there is an input from the tele button 12b or the wide button 12c in the auto zoom mode, the zoom control circuit 7 detects this (step S5). At this time, the control of the zoom lens by the auto zoom is temporarily stopped (step S6), and the manual zoom control is performed as in the manual mode (step S8).
During this time, the photographer operates the tele / wide buttons 12b and 12c to set a desired angle of view. When this operation is completed, the auto zoom control is started again. However, the reference value is updated by the memory control circuit 11 immediately before the start of the automatic zoom control (step S9). After changing the reference value in this way, the process returns to the automatic zoom control in step S4. In this way, the zoom magnification is automatically controlled so as to maintain the size of the subject reset by the manual operation.

As described above, in the first embodiment of the present invention,
The subject size can be easily changed by operating the tele / wide button during the operation of the auto zoom that automatically controls the subject size to be constant, thus improving the usability of the auto zoom function.

The portion 1 surrounded by a broken line in FIG.
3, that is, the zoom control circuit 7, the memory 10, and the memory control circuit 11 may be configured by a single microcomputer. By doing so, the circuit scale can be reduced.

Next, a second embodiment of the present invention will be described. To make the auto zoom function work well,
The imaging device needs to correctly extract the subject. If you cannot extract the target subject due to multiple objects in the screen or poor lighting conditions,
Auto zoom may not work as intended by the photographer. Therefore, it is convenient if the operator can confirm the extraction state of the subject. In the second example of the present embodiment,
The image pickup device is provided with at least a display unit that functions as an electronic viewfinder, and the extraction state of the subject is displayed together with the image.

FIG. 5 is a block diagram showing the structure of an image pickup apparatus according to the second embodiment of the present invention. In FIG. 5, the same components as those of the above-described embodiment are designated by the same reference numerals. However, the description thereof is omitted to avoid duplication (this also applies to each of the following embodiments). In FIG. 5, reference numeral 50 is a display unit using a liquid crystal display or the like. The subject extraction circuit 6 is configured to output a rectangular marker surrounding the extracted subject, add the video signal and this marker with the addition circuit 51, and output the added signal to the display unit 50. When the auto zoom button 12a is pressed once, the object in the center of the screen is recognized as a subject, and the subject is extracted by sampling the video signal and setting the extraction conditions as described above.

At this time, a quadrangle surrounding the extracted subject is displayed on the display unit 50. An example of this screen display is shown in FIG.
Shown in FIG. 6A is an image in the case of being correctly extracted, in which a person is a subject, and a quadrangle (marker 60) surrounding the person is superimposed. On the other hand, when the extraction state is poor and the quadrangle does not surround the subject as shown in FIG. 6B, the auto zoom button 12a is pressed to cancel the auto zoom, and then the auto zoom button 12 is pressed again.
Press a to reset the subject. There are many methods for displaying the extraction state, and a rectangle surrounding the subject may be displayed as shown in FIG. 6, or the subject area signal extracted by the subject extracting circuit 6 may be displayed as an image. It may be displayed by being superimposed on the signal.

As described above, the display of the extracted subject area may be performed only when the subject is set, but it may be displayed during the operation of the auto zoom. In this case, you can check the extraction status of the subject even during the automatic zoom operation.
When the extraction state deteriorates, the automatic zoom mode can be canceled or the subject can be reset.

As described above, in the second embodiment of the present invention, the photographer can confirm the extraction state of the subject, and after confirming that the subject is extracted well, the automatic zoom can be operated. , It is possible to prevent the malfunction of the auto zoom.

Next, a third embodiment of the present invention will be described. FIG. 7 is a block diagram showing the arrangement of an image pickup apparatus according to the third embodiment of the present invention. In the third embodiment of the present invention, a button 70 for subject setting is provided exclusively. When the subject setting button 70 is pressed once, a marker is displayed in the center of the screen. Adjust the direction of the camera so that the marker is on the subject, then press the subject setting button 7 again.
When 0 is pressed, the extraction area is displayed. When the subject setting button 70 is pressed again, the subject setting is completed.
When the auto zoom button 12a is pressed in this state, the auto zoom control is started, and when the auto zoom button 12a is pressed again, the auto zoom mode is released. The subject setting is valid even after the auto-zoom mode is released, and the subject information set last time is maintained even when the auto-zoom mode is entered again. The operation of changing the angle of view during the operation of the auto zoom is the same as in the first embodiment described above.

In the third embodiment, since the subject setting button 70 is provided separately from the auto zoom button 12a, the set subject information can be maintained and the operability is improved in the following points. That is, when zooming is temporarily stopped during the auto zoom mode and the same subject is to be photographed again in the auto zoom mode, it is not necessary to reset the subject when returning to the auto zoom mode. Moreover, when resetting the subject, it is not necessary to go through the auto zoom mode once.

Next, a fourth embodiment of the present invention will be described. FIG. 8 is a block diagram showing the arrangement of an image pickup apparatus according to the third embodiment of the present invention. In FIG.
80 is an AF (Auto Focus) that controls the focus lens
A motor and 81 are diaphragms.

In the fourth embodiment of the present embodiment, AE (Auto Exposure) and AF (Auto Focus) are combined with auto zoom. The subject is extracted in the automatic zoom control, and this subject information is used not only for the zoom control but also for AE and A.
It is also effective for F control. AE is a control for optimizing the brightness of the screen, but an important part in the screen is the subject.
Further, AF is a control for focusing, but even if the background portion is in focus, it is meaningless if the subject is not in focus. At this time, if it is known where the subject is on the screen, it is advantageous for AE and AF control. In the fourth example of the present embodiment, the zoom control is automatically performed, and at the same time, the performance of the AE and AF control is improved, so that the operability of the zoom is improved as in the other examples.
The image quality is also improved.

[0032]

As described above, according to the present invention, in an image pickup apparatus having an automatic zoom control function for keeping the size of a subject constant, the angle of view can be easily set, so that the image pickup apparatus is easy to use. Can be provided.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing a configuration example of a subject extraction circuit in FIG.

FIG. 3 is an explanatory diagram showing an example of an image for explaining the operation of the subject extraction circuit in the first embodiment example of the present invention.

FIG. 4 is a flowchart showing a processing flow of zoom control in the first embodiment example of the present invention.

FIG. 5 is a block diagram showing a configuration of an image pickup apparatus according to a second embodiment example of the present invention.

FIG. 6 is an explanatory diagram showing an example of a subject region display image in the second embodiment example of the present invention.

FIG. 7 is a block diagram showing a configuration of an image pickup apparatus according to a third embodiment example of the present invention.

FIG. 8 is a block diagram showing a configuration of an image pickup apparatus according to a fourth embodiment of the present invention.

[Explanation of symbols]

 1 Zoom Lens 2 Image Sensor 3 A / D Conversion Circuit 4 Signal Processing Circuit 5 D / A Conversion Circuit 6 Subject Extraction Circuit 7 Zoom Control Circuit 8 Zoom Motor 9 Output Terminal 10 Memory 11 Memory Control Circuit 12 Operation Button 12a Auto Zoom Button 12b Tele button 12c Wide button 13 Microcomputer 20 Binarization circuit 21 Comparison circuit 22 Region growth circuit 23 Memory 24 Feature amount calculation circuit 25 Sampling circuit 26 Extraction condition setting circuit 50 Display section 51 Addition circuit 60 Marker 70 Subject setting button 80 AF motor 81 aperture

Claims (8)

[Claims] 1. A zoom lens for continuously changing an optical zoom magnification, an imaging means for converting an optical image formed by the zoom lens into a video signal, and a subject extracted from the video signal, at least A subject extracting unit that outputs a feature amount including the size of the subject, a memory unit that stores the feature amount as a reference value in zoom control, and a size of the subject that is output by the subject extracting unit is stored in the memory unit. The zoom control means for automatically controlling the zoom magnification of the zoom lens and the automatic control of the zoom magnification by the zoom lens are temporarily stopped and the zoom magnification is manually changed so as to be substantially equal to the reference value. For manually inputting the zoom operation by the manual input means or during the completion of the input operation to the memory means. An image pickup apparatus comprising: a memory control unit that writes the characteristic amount and changes the reference value. 2. The zoom operation according to claim 1, wherein zoom mode switching means is provided, and an automatic zoom mode for performing zoom control according to claim 1 and automatic zoom magnification control are stopped, and a zoom operation is performed by the manual input means. An image pickup apparatus characterized in that it is configured to be able to switch to a manual zoom mode for performing only. 3. The feature according to claim 1, wherein at the same time when the automatic control of the zoom magnification is started, the subject extraction unit starts the extraction of the subject, and the memory control unit causes the memory unit to store the features. An imaging device, which writes a quantity. 4. A zoom lens for continuously changing an optical zoom magnification, an image pickup means for converting an optical image formed by the zoom lens into a video signal, and a subject setting means for setting a subject. A subject extracting unit that extracts a subject from the video signal and outputs a feature amount including at least the size of the subject; a memory unit that stores the feature amount as a reference value in zoom control; and an output from the subject extracting unit. The zoom control means for automatically controlling the zoom magnification of the zoom lens and the automatic control of the zoom magnification by the zoom lens are temporarily set so that the size of the subject becomes substantially equal to the reference value stored in the memory means. Manual input means for manually changing the zoom magnification while stopping, and a zoom operation input period by the manual input means An image pickup apparatus comprising: a memory control unit that writes the characteristic amount into the memory unit and changes the reference value when the input is completed, or an image of a portion designated by the subject setting unit. An image pickup apparatus, which acquires information and determines an initial extraction condition for subject extraction using the image information. 5. The automatic focusing device according to claim 1, further comprising: an automatic focusing unit that automatically focuses, and controls to focus an image in the subject extraction area. Image pickup device. 6. The image pickup device according to claim 1, further comprising an exposure control unit, which controls exposure so that a luminance signal level of an image in a subject extraction area becomes constant. . 7. A zoom lens for continuously changing an optical zoom magnification, an image pickup means for converting an optical image formed by the zoom lens into a video signal, and a subject extracted from the video signal, at least A subject extracting unit that outputs a feature amount including the size of the subject, a memory unit that stores the feature amount as a reference value in zoom control, and a size of the subject that is output by the subject extracting unit is stored in the memory unit. The zoom control means for automatically controlling the zoom magnification of the zoom lens and the automatic control of the zoom magnification by the zoom lens are temporarily stopped and the zoom magnification is manually changed so as to be substantially equal to the reference value. For manually inputting the zoom operation by the manual input means or during the completion of the input operation to the memory means. Memory control means for writing the characteristic amount and changing the reference value, synthesizing means for superimposing the extracted subject region on the video signal, and display means for displaying an output signal of the synthesizing means are provided. An imaging device characterized by the above. 8. The image pickup apparatus according to claim 7, wherein the subject area is displayed by a quadrangle that circumscribes the subject.