JP2776426B2 - Zooming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zooming system for a video camera.

[0002]

2. Description of the Related Art Conventionally, there has been a mechanical zooming method in which a zoom lens is mechanically and continuously moved as zooming of a video camera. Further, there is also an extender insertion type zooming method in which an extender is used for this purpose and the magnification is instantaneously changed by inserting the extender into a lens system when desired. Further, in addition to the mechanical zooming method, an electronic zoom combined method of electronically zooming using a field memory in order to achieve a higher magnification when a predetermined magnification is reached. Zooming method.

[0003]

By the way, in the present consumer video camera, high speed zooming,
In some cases, there is a demand for a slower zooming or a multifunctional zooming system that allows the size of the angle of view to be changed in multiple stages in an instant. Further, in addition to that, further reduction in size and weight and reduction in price are required.

In response to these demands, in the mechanical zooming system and the electronic zooming system, the zooming speed is low and the zooming is continuously performed. To do so, the eyes were very tired for the operator. In some cases, slower zooming is desired, and in such a case, the request cannot be answered.

Further, in the zooming system of the extender insertion system, although the magnification can be changed only once in a moment, it cannot be switched in multiple stages, and the apparatus becomes large and heavy. There was a problem that said. Therefore, a problem to be solved by the present invention is to solve the above problems.

[0006]

SUMMARY OF THE INVENTION The present invention aims at providing a zooming system having the following constitutions 1) and 2) in order to solve the above-mentioned problems. 1) a mechanical zoom system for changing an incoming optical image to a predetermined magnification by moving a zoom lens system having a zoom characteristic represented by a predetermined straight line or curve; The zoomed image from the lens lens system is photoelectrically converted by a solid-state imaging device, the photoelectrically converted image signal is stored in a storage unit, and the stored image signals are sequentially read out and scaled to a predetermined magnification. In the zooming system including an electronic zoom system, the electronic zoom system is scaled so as to cancel out the zoom characteristic of the mechanical zoom system at predetermined intervals, and is sequentially read out. The angle of view of the image signal
A zooming method characterized in that the magnification is changed stepwise.

2) a mechanical zoom system which has a zoom characteristic in which an incoming optical image is represented by a predetermined straight line or curve and moves the zoom lens system at a predetermined speed to change the magnification to a predetermined magnification; The scaled image from the zoom lens system is photoelectrically converted by a solid-state imaging device, the photoelectrically converted image signal is stored in a storage unit, and the stored image signals are sequentially read out and scaled to a predetermined magnification. In the zooming system comprising an electronic zoom system for, in the electronic zoom system, the sequentially read image signal, by changing the zoom characteristic represented by a predetermined straight line or curve,
A combination of the zoom system and the mechanical zoom system
Double speed is faster than the variable speed of the mechanical zoom system.
Or a zooming method characterized in that selection can be made to be slow .

[0008]

This is a method in which an incoming optical image is scaled by a mechanical zoom system, this image is temporarily stored in a storage means, the stored image is read out, and scaled by an electronic zoom system. In the electronic zoom system, the zooming characteristic of the mechanical zoom system is scaled so as to be canceled at predetermined intervals to obtain an angle of view that changes in a stepping manner. Further, in the electronic zoom system, the zoom of the mechanical zoom system is used.
Zoom characteristic expressed by a predetermined straight line or curve
Change the magnification speed by changing the magnification with the system characteristics.

[0009]

An embodiment of the present invention will be described below with reference to the drawings. First, the principle of the zooming method according to the embodiment of the present invention will be described. FIG. 1 is a straight line showing the zoom characteristics of a mechanical zoom system. The vertical axis indicates the zoom magnification, and the horizontal axis indicates the zooming operation time. This
The straight line is a straight line that can be expressed by logY = kt if the inclination is k. FIG. 2 is a curve showing the zoom characteristic of the electron zoom system. In this figure, zooming from zoom magnification 2
A straight line having a slope of -k is repeated at a predetermined cycle.

For example, when the mechanical zoom system and the electronic zoom system are combined, the inclinations k and -k of each other are canceled at predetermined intervals, and a step-like combined curve as shown in FIG. Is obtained. This composite curve means that the magnification can be switched in multiple stages in an instant. The number of switching steps ST can be obtained by the following equation.
The desired number of steps is obtained. That is, if the mechanical zoom magnification is n times and the electron zoom magnification is m times, a relational expression of ST ≦ logn / logm is established. For example, the mechanical zoom magnification is 8 times and the electronic zoom magnification is 8 times. Assuming that the zoom factor is 2, the number of switching steps is three. If the mechanical zoom magnification is 8 times and the electronic zoom magnification is 1.5 times, the number of switching steps is 5 steps.

Next, an embodiment of this step-like zooming method (hereinafter referred to as stepping zooming method) will be described based on a specific example applied to an image pickup apparatus. FIG. 4 is a schematic block diagram of the imaging device. In FIG. 1, reference numeral 1 denotes a zoom lens system having a built-in focus lens. The imaging light coming from the zoom lens system 1 is photoelectrically converted by a CCD (solid-state image sensor) 2, and this signal is transmitted to the next stage. An S / H (sample hold) AGC (auto gain control) circuit 3 is provided, where the incoming signal is sampled and gain controlled. You.

Further, this signal is supplied to an A / D (analog / digital) conversion circuit 4, where it is converted into, for example, a 9-bit digital signal. The digital signal is further supplied to a luminance signal processing circuit 5, where the digital signal is subjected to signal processing such as optical black clamp, gamma correction, color signal removal, and aperture correction. The output signal is supplied to an edge detection / integration circuit 6, a color signal processing circuit 7,
It is supplied to the motion vector detection circuit 8 and the interpolation / electronic zoom circuit 9, respectively.

The edge detection / integration circuit 6 extracts a high-frequency component to detect focus information, or obtains an integrated value for each block by dividing the screen into a plurality of parts by an integrator in this circuit. The information is supplied to the microcomputer 10 through the data bus a. On the other hand, the microcomputer 10 is supplied with positional information of the zoom lens and the master lens in the zoom lens system 1, and here, these information and the edge detection / integration circuit 6 are supplied. Based on this information, the in-focus position of each lens, the aperture value of the iris, the shutter speed of the CCD 2, etc. are calculated, and the microcomputer 1
A zoom correction amount is read from a table in 0, and respective drive signals for driving the CCD drive circuit 11, the AF drive circuit 12, the iris drive circuit 13, and the lens drive circuit 14 are generated. And supplied to each circuit. Thus, a so-called mechanical zoom system is formed.

On the other hand, in the color signal processing circuit 7, line-sequential color difference signals RY and BY are extracted by a matrix circuit in this circuit, and these color difference signals are subjected to processes such as gamma correction and noise reduction. Thereafter, the line-sequential color difference signals are synchronized and supplied to the interpolation / electronic zoom circuit 9 at the next stage. On the other hand, the motion vector detection circuit 8 detects a motion vector based on the incoming current signal and the signal of each representative point one field before, and this data is transmitted via the data bus b. It is supplied to a microcomputer 15 for camera shake prevention and electronic zoom control, where the amount of movement is obtained. As a result, when camera shake correction is required, a control signal is supplied to the interpolation / electronic zoom circuit 9 from here.

In the interpolation / electronic zoom circuit 9, read signals are supplied to the luminance signal field memory 16 and the chrominance signal field memory 17 based on the control signals, and based on the read signals, the memories 16 and 17 are supplied. Each corresponding image is read. Then, after this image is cut out in a predetermined range, the image is enlarged to a predetermined angle of view and the camera shake correction is performed.

When the zoom operation switch SW1 is operated, a drive signal is supplied from the microcomputer 10 to the lens drive circuit 14, and an image having a magnification corresponding to the operation time is obtained. In the present embodiment, the S
When the operation of W1 is continued and the magnification is set to 8 times, the microcomputer 10 detects this and the information is stored in the data.
It is supplied to the microcomputer 15 through the tabus c. The microcomputer 15 supplies a control signal to the interpolation / electronic zoom circuit 9 through the data bus b based on this information. The interpolation / electronic zoom circuit 9 retrieves an image to be zoomed from the field memories 16 and 17 on the basis thereof, cuts out a predetermined image, and increases the image by, for example, 9 times or more according to the operation time. An enlarged image up to double the size is obtained. That is, the electronic zoom process is performed by this.

Next, here, for example, steppings
When the zoom switch SW2 is turned on and the zoom operation switch SW1 is operated, a control signal is supplied from the microcomputer 15 to the interpolation / electronic zoom circuit 9. At this time, the image signals enlarged based on the zoom characteristics as shown in FIG. 1 through the interpolation / electronic zoom circuit 9 are stored in the field memories 16 and 17, and the control signals are Based on these signals, interpolation and electronic zoom
After the signals are read out by the zoom circuit 9 and cut out into an image of a predetermined size, the signals are sequentially multiplied by a magnification coefficient having a zoom characteristic shown in FIG. 2, and as shown in FIG. An image that changes in various steps is obtained.

Further, in the image pickup apparatus according to the present embodiment, a switch SW3 for controlling a zooming speed is provided in addition to the switch SW2, so that a second characteristic zooming method is provided. providing. In this method, the zooming speed is changed by using both mechanical zoom and electronic zoom. This principle will be described with reference to FIG. A straight line 1 indicates a mechanical zoom straight line, and a straight line 2 indicates an electronic zoom straight line. These combined straight lines are shown as a straight line 3. As is clear from this, both
It can be seen that the zoom time becomes shorter if the zoom characteristics are used together. Conversely, when the electron zoom having the characteristic inclined in the negative direction as shown by the straight line 4 and the mechanical zoom having the characteristic of the straight line 1 are used in combination, a slow movement as shown by the straight line 5 is obtained. Zoom characteristics can be obtained. The present method utilizes this characteristic.

For example, when the switch SW3 is operated to the [high speed] side when the zoom operation switch SW1 is operated, a control signal is supplied from the microcomputer 15 to the interpolation / electronic zoom circuit 9 and read out from the field memories 16 and 17. The obtained image is multiplied by a coefficient having a zoom characteristic indicated by a straight line 2, and as a result, the zoom characteristic indicated by a straight line 3 is obtained and a scaled image is obtained at high speed. When the SW3 is operated to the [low speed] side, the zoom characteristic indicated by the straight line 4 is multiplied instead of the straight line 2, and as a result, the zoom characteristic indicated by the straight line 5 is obtained. , A zoomed image with a slow speed is obtained. In this case,
As can be seen, it is used to increase the zoom speed
Reduce the characteristics of line 2 (electronic zoom) and the zoom speed
The characteristic of the straight line 4 (electronic zoom) used for
The rate of increase / decrease is opposite to each other.
Get the same zoom magnification using the characteristics of the straight lines 2 and 4
In this case, using the characteristics of the straight line 4
The ratio depending on the magnification of Kal zoom increases, and naturally
When using the characteristics of line 4 (when the speed is reduced)
Is better when the characteristic of the straight line 4 is used.
Case) A better image can be obtained.

In the interpolation / electronic zoom circuit 9, the two color difference signals and the luminance signal subjected to camera shake correction, zoom processing, and the like are supplied to an encoder processing circuit 18 in the next stage. Here, a title character or the like is superimposed on a RAM (random access memory) 1 based on a synchronization signal of a title control circuit (not shown) as necessary.
9 and, when desired, this information is called up and superimposed on the incoming signal as a title signal, or two color difference signals are balanced-modulated, and a modulated color signal and a luminance signal are output. And The microcomputer 20 controls a luminance signal processing circuit 5, a chrominance signal processing circuit 7, an encoder processing circuit 18, and a microcomputer 15 for controlling the setup and gain of the microcomputer 15 through a data bus d. It is.

In the above description of the embodiment, the characteristics of the mechanical zoom and the electronic zoom are described as linear characteristics. However, the present invention is not limited to this. Of course, the characteristics may be good.

Therefore, according to the above embodiment, the switch S
By activating W3, an enlarged image can be obtained quickly and eyestrain is not felt, and since the image is obtained in combination with the mechanical zoom system, a step-like image can be formed only by the electronic zoom. High image quality can be obtained compared to what is obtained. In addition, a moving image is obtained for the image between the steps, so that the image does not feel unnatural. Further, since the electronic zoom is used in combination, it is not necessary to provide an extender or the like, and the size and weight can be reduced. Further, by operating the switch SW3, the zoom speed can be increased or decreased, so that more functions can be realized.

[0023]

According to the first aspect of the present invention, a zoomed image can be obtained quickly so as not to cause eyestrain, and the image is obtained by using both the electronic zoom system and the mechanical zoom system. In addition, higher image quality can be obtained as compared with a method in which a step-like image is obtained only by the electronic zoom system. In addition, a moving image is obtained for the image between the steps at the time of zooming, so that there is no unnaturalness. Also, there is no need to provide extra parts such as extenders, and the size and weight can be reduced. According to the method of the second aspect, the selection range of the desired speed at the time of zooming is higher than before.
When zooming is slowed down as the
Zooming with an emphasis on image quality can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing zoom characteristics of a mechanical zoom system of the present embodiment.

FIG. 2 is a diagram illustrating zoom characteristics of an electron zoom system.

FIG. 3 is a diagram showing the synthetic characteristics of a mechanical zoom system and an electronic zoom system.

FIG. 4 is a block diagram of an imaging apparatus to which a zoom method according to an embodiment of the present invention is applied.

FIG. 5 is a principle diagram for explaining a shift zoom.

[Explanation of symbols]

 Reference Signs List 1 zoom lens system 2 CCD (solid-state imaging device) 4 A / D (analog / digital) conversion circuit 5 luminance signal processing circuit 6 edge detection / integration circuit 7 color signal processing circuit 8 motion vector detection circuit 9 interpolation / electronic zoom System circuit 10, 15, 20 Microcomputer 11 CCD drive circuit 12 AF drive circuit 13 Iris drive circuit 14 Lens drive circuit 1 16, 17 Field memory 18 Encoder processing circuit SW1, 2, 3 Switch

Claims (2)

(57) [Claims] 1. A mechanical zoom system for changing an incoming optical image to a predetermined magnification by moving a zoom lens system having a zoom characteristic represented by a predetermined straight line or curve, and said zoom. A photoelectric conversion of a scaled image from the lens system by a solid-state imaging device, storing the photoelectrically converted image signal in a storage means, sequentially reading out the stored image signal, and scaling the image signal to a predetermined magnification. In the zooming system comprising the electronic zoom system, the electronic zoom system is scaled so as to cancel out the zoom characteristics of the mechanical zoom system at predetermined intervals, and the sequential reading is performed. A zooming method in which the angle of view of an image signal to be reproduced is changed in a stepwise manner. 2. A mechanical zoom system for zooming an incoming optical image to a predetermined magnification by moving a zoom lens system at a predetermined speed and having a zoom characteristic represented by a predetermined straight line or curve. The scaled image from the zoom lens system is photoelectrically converted by a solid-state imaging device, the photoelectrically converted image signal is stored in a storage unit, and the stored image signals are sequentially read out and scaled to a predetermined magnification. A zooming system comprising: an electronic zoom system for performing zooming on the sequentially read image signal by a zoom characteristic represented by a predetermined straight line or curve, wherein the zoom system and the mechanical zoom system And
The variable magnification speed used in combination with the mechanical zoom
A zooming method characterized in that it can be selected to be faster or slower than a degree .