JP2005203934A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system with the lower limit value of a gain obtained from divergence set to a value greater than 0, unlike as in prior art where a camera-shake correction function is interrupted during an operation of optical zooming due to divergence processing of a motion vector, for an imaging apparatus having optical zooming function and the camera-shake correction function for detecting camera-shake information from a video signal. <P>SOLUTION: The imaging apparatus selects gain characteristics, wherein the gain is not set to zero when instability due to camera-shake is conspicuous at a comparatively low optical zooming speed in the processing of calculating the gain from the divergence and can obtain a stable image whose camera-shake is corrected, even during the operation of the optical zooming. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image pickup apparatus with an optical zoom that detects a motion vector from a video signal and performs camera shake correction according to the motion vector.

  In recent years, imaging devices represented by video cameras and digital still cameras have become smaller and have higher magnification, and image stability due to camera shake has become an issue, and most have image stabilization functions. Yes.

  Further, in order to further reduce the size and cost, a method for obtaining motion information of a camera shake from a video signal has been commercialized.

  However, in the method of obtaining a motion vector from a video signal, unlike the method of obtaining blur information from a sensor typified by an angular velocity sensor, a motion vector is generated due to a change in the subject even when the optical zoom is in operation, resulting in malfunction. It becomes a factor of.

  Therefore, in the conventional image pickup apparatus of the first example, as described in Japanese Patent Application Laid-Open No. 11-177786, during the optical zoom operation, control is performed so as to ignore the output of the motion detection circuit, thereby preventing malfunction. is doing.

  Further, in the conventional image pickup apparatus of the second example, the operation when the motion vector detection apparatus described in Japanese Patent No. 2506469 is mounted will be described with reference to FIGS.

  In FIG. 7, 1 is a lens having an optical zoom function, 2 is a zoom switch for controlling a wide-angle operation or a telephoto operation by the zoom function of the lens 1, and 3 is a speed of the optical zoom by a pressure applied to the zoom switch 2. A zoom speed setting circuit 4 for setting is an imaging unit that converts an optical signal having subject information input through the lens 1 into an electrical signal by a two-dimensional solid-state imaging device, further processes the electrical signal and outputs it as a video signal 5 is a motion vector detection circuit that divides the video signal into a plurality of regions and detects a motion vector in each region; 6 is a reliability determination circuit that determines whether the motion vector detected in each region is valid; 7 is a difference vector determining circuit for determining a vector of the entire screen from vectors of the area determined to be valid by the reliability determining circuit 6, and 8 is a previous one. A divergence calculation circuit that calculates / numerizes the degree of dispersion of the motion vectors determined to be effective by the reliability determination circuit 6 as a divergence, and 19 is a gain determination circuit that determines a gain from the divergence. Reference numeral 10 denotes a gain control circuit for performing processing for multiplying the difference vector by the gain.

  The operation principle of the second conventional imaging apparatus having the above configuration will be described with reference to FIGS.

  First, an optical signal having object information obtained through the lens 1 is converted into a video signal by the imaging unit 4. Then, the motion vector detection circuit 5 divides one screen into a plurality of areas and extracts camera shake information of the imaging device included in the video signal as a motion vector in each area.

  As a typical process of the motion vector detection circuit 5, a correlation operation is performed between the video signal at the current time and the video signal before unit time output from the two-dimensional solid-state imaging device such as one field before or one frame before. Calculate by doing. Since specific processing methods are described in detail in Japanese Patent Application Laid-Open Nos. 61-269475 and 2-241188, they are omitted here.

  Here, FIG. 8A and FIG. 8B show the state of motion vectors detected in each region.

  In FIG. 8, the area is divided into four, and FIG. 8A shows a motion vector at a certain time when a shake is detected in the upper right direction, and FIG. 8B shows a subject randomly in the screen. A motion vector at a certain time when moved is shown.

  In the state of FIG. 8 (a), the vectors in each region are generated in directions and magnitudes close to the same, so that any motion vector in the four regions can be selected and corrected as intended. Camera shake correction is possible.

However, in the case of FIG. 8B, since the motion vectors in each region are not uniform in direction, there is a possibility that an erroneous difference vector is detected, which causes a malfunction.
Therefore, in the conventional image pickup apparatus of the second example, the motion vector detection circuit 5 uses the motion vector of the region determined to be effective by the reliability determination circuit 6 from the motion vector detected from each region. The arithmetic processing shown by the equation (1) is performed, and the degree of dispersion of the motion vector is quantified as the divergence.

Formula (1) ... Divergence = {Σ | (average value of motion vectors in each region)
− (Motion vector of each region) |} / (number of regions determined to be valid)
In the numerator of Expression (1), “motion vector of each region” is a vector of a region determined to be effective by the reliability determination circuit 6.

  Based on the divergence, the gain determination circuit 19 obtains the gain from the characteristics as shown in FIG. 9, and the gain control circuit 10 multiplies the difference vector by the gain to obtain a vector for camera shake correction.

By performing the above control, when the degree of dispersion is large, that is, when the degree of divergence is large, the gain is set to 0 or a value close to 0, thereby suppressing the difference vector and preventing malfunction.
Japanese Patent Laid-Open No. 11-177876 Japanese Patent No. 2506469

  However, the configuration of the conventional first imaging device has a problem that the camera shake correction does not work even when camera shake is a concern, such as when the optical zoom of the imaging device is operated at a low speed. Was.

  Further, in the configuration like the conventional second image pickup device, when the optical zoom of the image pickup device is operated, the divergence increases due to the optical zoom, the gain multiplied by the motion vector becomes 0, and the camera shake correction does not work. Had problems.

  SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an imaging apparatus capable of correcting camera shake and obtaining a stable image even when instability due to blurring is noticeable during relatively slow zooming.

  In order to solve the above problems, a first imaging device of the present invention outputs a lens that enables the size of a subject to be changed by an optical zoom function, and an optical signal having information on the subject as a video signal. An image pickup unit, a zoom position detection circuit that detects the magnification of the optical zoom, a motion vector detection circuit that divides the video signal into a plurality of regions and detects a motion vector in each region, and a motion in each region A reliability determination circuit for determining the validity of a vector, a difference vector determination circuit for outputting a motion vector of the entire screen as a difference vector from the areas validated by the reliability determination circuit, and reliability determination for each area A divergence calculation circuit for calculating a divergence degree indicating a degree of dispersion of the motion vector of the entire screen from a motion vector of an area determined to be valid by the circuit; A gain determining circuit for determining a gain within a range of 0 to 1 times or less, and a gain control circuit for multiplying the difference vector by the gain determined by the gain determining circuit. The divergence degree when not operating, or when the optical zoom speed is relatively high and instability due to blurring is not noticeable, and when the optical zoom speed is relatively slow and instability due to blurring is noticeable The gain characteristics obtained from the above are switched.

  The second imaging device of the present invention includes a lens that enables the size of a subject to be changed by an optical zoom function, an imaging unit that outputs an optical signal having information on the subject as a video signal, and the optical A zoom position detection circuit for detecting a zoom magnification, a motion vector detection circuit for detecting a motion vector in each region by dividing the video signal into a plurality of regions, and determining the effectiveness of the motion vector in each region A reliability determination circuit; a difference vector determination circuit that outputs a motion vector of the entire screen as a difference vector from a region that has been validated by the reliability determination circuit; and an integration that time-integrates the difference vector and outputs the integration vector as an integration vector Dispersion of motion vectors of the entire screen from the motion vectors of the regions determined to be valid by the vector calculation circuit and the reliability determination circuit of each region A divergence calculating circuit for calculating a divergence indicating a match; a circuit for determining a gain within a range of 0 to 1 times or less than the divergence; and a gain for multiplying the integral vector by a gain obtained by the gain determining circuit A control circuit, and in the gain determination circuit, when the optical zoom is not operating, or when the optical zoom speed is relatively high and instability due to blurring is not noticeable, the optical zoom speed is relatively low Thus, the gain characteristic obtained from the divergence is switched when the instability due to the shake is conspicuous.

  According to the configuration of the present invention, it is possible to perform camera shake correction and provide a stable image even when instability due to blurring is noticeable during relatively slow zooming with the conventional configuration.

  The invention described in claims 1 to 2 of the present invention includes a lens that can optically change the size of a subject, an imaging unit that outputs an optical signal having information on the subject as a video signal, Zoom position detecting means for detecting the magnification of the optical zoom, motion vector detecting means for dividing the video signal into a plurality of areas and detecting a motion vector in each area, and determining the validity of the motion vector in each area Reliability determining means, difference vector determining means for determining a motion vector of the entire screen from the areas validated by the reliability judging means, and areas determined to be valid by the reliability judging means of each area A divergence degree calculating means for calculating a divergence degree indicating the degree of dispersion of the motion vector of the entire screen from the motion vector of the image, and a divergence degree from the divergence degree calculating means within a range of 0 to 1 times or less Gain determining means for determining the gain and gain control means for multiplying the motion vector by the gain determined by the gain determining means, and when the optical zoom is not operating in the gain determining means or the optical zoom speed The gain characteristic obtained from the divergence is switched between when the instability due to blur is not noticeable and when the optical zoom speed is relatively low and when instability due to blur is noticeable. As a characteristic when there are multiple characteristics of divergence and gain and the optical zoom is relatively slow, the lower limit of the gain is not set to 0, but the camera shake effect during the optical zoom operation is recognized. By setting it as possible, it is possible to reduce instability due to blur during low-speed zooming and provide a stable image.

(Embodiment 1)
An image pickup apparatus according to a first example of the present invention will be described with reference to FIGS.

  FIG. 1 is a block diagram of an image pickup apparatus according to the present invention. In the figure, 1 is a lens having an optical zoom function, 2 is a zoom switch for controlling wide-angle operation or telephoto operation by the zoom function of the lens 1, and is a push button type. Often consists of switches and levers. Reference numeral 3 denotes a zoom speed setting circuit that sets the speed of the optical zoom by the pressure applied to the zoom switch 2. In this embodiment, the speed is controlled by the pressure applied to the zoom switch 2, but the speed is not necessarily limited to the pressure. Absent. An image pickup unit 4 is an image pickup unit that converts an optical signal having subject information input through the lens 1 into an electric signal by a two-dimensional solid-state image pickup device, further processes the electric signal and outputs it as a video signal. Or a CMOS sensor is used. Reference numeral 5 denotes a motion vector detection circuit which is a motion vector detection means for dividing a video signal from the imaging unit 4 into a plurality of areas and detects a motion vector in each area. Reference numeral 6 denotes a motion vector detection circuit 5 which detects the motion vector in each area. A reliability determination circuit which is a reliability determination means for determining whether or not the motion vector is valid, and 7 is a difference vector determination for determining a vector for the entire screen from the vectors of the area determined as “valid” by the reliability determination circuit 6. A difference vector determining circuit 8 is a divergence degree calculating means for calculating / numerizing the degree of dispersion with a “divergence degree” among motion vectors determined as “valid” by the reliability judgment circuit 6. A divergence calculation circuit 10 is a gain control means for performing a process of multiplying a difference vector from the difference vector determination circuit 7 by a gain from a gain determination circuit 9 (described later). The control circuit, 9 is a gain determination circuit that is a gain determination means for determining the gain from the divergence calculated by the divergence calculation circuit 8, and 11 is a zoom position detection circuit that detects the optical zoom position in the lens 1. In this case, the position of the zoom lens in the optical axis direction is detected, or the zoom position is detected based on zoom position information already digitized.

  Hereinafter, the operation will be described focusing on the contents different from the conventional second example. Similar to the second example of the prior art, the variance of the difference vector, that is, the divergence is calculated via the lens 1, the imaging unit 4, the motion vector detection circuit 5, and the divergence calculation circuit 8, and is input to the gain determination circuit 9. .

  Thereafter, the gain is calculated by the gain determining circuit 9, but the method of obtaining the gain from the divergence from the divergence calculating circuit 8 is different from the conventional second example.

  FIG. 2 shows an internal block diagram of the gain determination circuit 9. In FIG. 2, 21 and 22 are a characteristic A holding unit and a characteristic B holding unit that hold the gain characteristic with respect to the divergence, 21 holds the characteristic A, and 22 holds the characteristic B. As clearly shown in FIG. 2, the gain is obtained only by the characteristic A in the prior art, but in the first embodiment, the gain is larger than 0 even if the divergence increases, as indicated by the characteristic B. A control for calculating the gain is provided with such a characteristic that the clip is applied with a value smaller than double (here, “α”). Reference numeral 24 denotes an optical zoom speed determination unit, 24 denotes an optical zoom speed determination unit that controls the selector 23 by determining the optical zoom speed from the optical zoom speed information and the optical zoom position information, and 23 denotes an optical zoom speed determination unit 24. This selector is a selector that switches between the characteristic A holding unit 21 and the characteristic B holding unit 22 under control and outputs a gain.

  As a specific control means, first, based on the optical zoom speed information, during the optical zoom operation, it is determined whether the zoom speed is relatively slow so that the instability of the image due to shaking is noticeable or not. The characteristic B is selected for (low speed zoom), and the characteristic A is selected for the latter (high speed zoom).

  Here, the reason why the zoom position information is required is that, for example, when the optical zoom speed information is controlled by the pressure applied to the zoom switch 2 as shown in FIGS. When pressure is applied to the switch 2 and an optical zoom operation command is output from the zoom speed setting circuit 3 to the lens 1 at a certain zoom speed, if the optical zoom position reaches the telephoto end or the wide angle end, the optical zoom is Does not work. Therefore, at this time, since the optical zoom is the same as the OFF state in this control, the characteristic A is selected as in the conventional case.

  As described above, according to the present embodiment, even in a situation where the optical zoom speed is relatively low and the instability of camera shake is conspicuous, conventionally, the gain obtained from the divergence is almost forcibly reduced to 0 and camera shake correction is performed. On the other hand, in the present invention, it is possible to provide a good image by setting the gain lower limit value (α in FIG. 2 characteristic B) so that the effect of camera shake correction is recognized. Become.

(Embodiment 2)
An imaging apparatus according to the second embodiment of the present invention will be described with reference to FIG.

  FIG. 5 is a block diagram of the imaging apparatus according to the present embodiment, and the lens 1 to zoom position detection circuit 11 are blocks having the same functions as those of the first embodiment of the present invention.

  The difference from the first embodiment is that the first embodiment controls the gain obtained from the divergence degree to a motion vector in a unit time period, that is, a difference vector, whereas in the second embodiment, the difference vector is This is the point to control to the integral vector that is time integrated. Therefore, the gain control circuit 10 has the same function as that of the first embodiment, but is different in that the input signal changes from the difference vector to the integration vector.

  Here, the difference between the difference vector and the integral vector will be described with reference to FIG. First, the state of an image at a certain reference time is shown in FIG. Next, FIG. 6B shows a state in which the subject “A” has moved in the upper right direction from the reference time due to camera shake during a certain unit time. Therefore, the difference vector is generated in the upper right direction.

  Next, FIG. 6C shows a state in which the camera moves due to camera shake in a certain unit time period in a slightly lower left direction from the state of FIG. 6B, and from the state of FIG. A difference vector is generated in the slightly lower left direction. Hereinafter, FIG. 6D is a state diagram in which the camera shakes slightly upward from the state of FIG. 6C.

  As described above, FIG. 6A to FIG. 6B, FIG. 6B to FIG. 6C, and FIG. 6C to FIG. Therefore, when integrated, FIG. 6 (a) to FIG. 6 (d) move in the lower left direction, which is an integration vector. Then, using this integral vector, camera shake correction is performed using a memory or the like.

  Therefore, performing gain control on the integral vector as in the imaging apparatus of the second embodiment provides the same effect as the control performed on the difference vector described in the first embodiment.

  Note that, as the characteristics of the gain determination circuit 9 in the present invention, both the first and second embodiments have been described with the control selected from the characteristics of the two patterns, but the number of gain characteristics patterns is increased from information such as the speed of the optical zoom. Thus, further performance improvement can be achieved.

  By introducing the control described in the configuration of the present invention to a device that focuses on moving images such as a video camera, a photographer can select a specific subject (such as a person or a flower) using these devices. This can be effective when shooting while adjusting the angle of view as a target.

FIG. 1 is a block diagram showing a basic configuration according to Embodiment 1 of the present invention. Internal block diagram of gain determination circuit 9 in Embodiment 1 of the present invention First characteristic diagram showing the relationship between the pressure applied to the zoom switch and the zoom speed in the optical zoom speed control according to the third embodiment of the first embodiment of the present invention. Second characteristic diagram showing the relationship between the pressure applied to the zoom switch and the zoom speed in the speed control of the optical zoom in the third embodiment in the first embodiment of the present invention. The block diagram which shows the basic composition in Embodiment 2 of this invention. Schematic diagram showing difference vector and integration vector in the same embodiment Block diagram showing basic configuration in the past Schematic diagram showing the degree of dispersion of conventional motion vectors Input / output characteristic diagram of conventional gain determination circuit 9

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens 2 Zoom switch 3 Zoom speed setting circuit 4 Image pick-up part 5 Motion vector detection circuit 6 Reliability determination circuit 7 Difference vector determination circuit 8 Divergence calculation circuit 9 Gain determination circuit 1 Gain control circuit 11 Zoom position detection circuit

Claims (2)

A lens capable of optically changing the size of the subject, an imaging means for outputting an optical signal having information on the subject as a video signal, a zoom position detecting means for detecting the magnification of the optical zoom, Effective in the motion vector detection means for detecting the motion vector in each area by dividing the video signal into a plurality of areas, the reliability judgment means for judging the validity of the motion vector in each area, and the reliability judgment means The difference vector determination means for determining the motion vector of the entire screen from the determined areas, and the degree of dispersion of the motion vector of the entire screen from the motion vectors of the areas determined to be valid by the reliability determination means of each area A divergence degree calculating means for calculating a divergence degree, a gain determining means for determining a gain in a range of 0 to 1 times or less than the divergence degree from the divergence degree calculating means; Gain control means for multiplying the motion vector by the gain determined by the determination means, and when the optical zoom is not operating in the gain determination means or the optical zoom speed is relatively high and the instability due to shaking is An image pickup apparatus, wherein the gain characteristic obtained from the divergence is switched between an inconspicuous case and a case where the optical zoom speed is relatively low and instability due to blurring is conspicuous. A lens capable of changing the size of a subject by optical zoom, an imaging unit that outputs an optical signal having information on the subject as a video signal, a zoom position detection circuit that detects a magnification of the optical zoom, and Effective in the motion vector detection circuit that detects the motion vector in each region by dividing the video signal into a plurality of regions, the reliability determination circuit that determines the validity of the motion vector in each region, and the reliability determination circuit A difference vector determination circuit that determines a difference vector from the regions defined as above, an integration vector calculation circuit that outputs the difference vector as a time-integrated vector (hereinafter referred to as an integration vector), and a reliability determination circuit for each region A divergence calculation circuit that calculates a divergence degree indicating the degree of dispersion of the motion vector of the entire screen from the motion vector of the area determined to be valid; A circuit for determining a gain within a range of 0 to 1 times or less than the divergence, and a gain control circuit for multiplying the integral vector by the gain determined by the gain determination circuit. When the zoom is not operating, or when the optical zoom speed is relatively high and instability due to blurring is not noticeable, and when the optical zoom speed is relatively slow and instability due to blurring is noticeable, An image pickup apparatus characterized by switching a characteristic with the gain obtained from a divergence degree.

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