JP2007336257A - Imaging device having focus-assisting function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging device capable of easily adjusting a focus for the imaging device having a video output having a high accuracy without a sense of incompatibility, while ensuring a video for a display device capable of treating only a video signal having a lower accuracy. <P>SOLUTION: A video-data synthetic changeover means 3 conducts a synthesis or a changeover with a low-accuracy whole video for confirming an angle of view converted into the video signal having the lower accuracy by a normal format conversion means 1, by carrying out an exclusive image-quality improving processing to an enlarged video for confirming a focusing by a noise reducing means 4. The sense of incompatibility at a time when the video signal is displayed as one for a view finder is reduced, and the focus can be adjusted easily. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an imaging apparatus such as a video camera or a still camera, and more particularly, an imaging apparatus with a focus assist function that captures a high-definition video signal while simply confirming it on a display device that can handle only a low-definition video signal. It is about.

  Conventional imaging devices such as video cameras and still cameras are equipped with a viewfinder for the photographer to check the subject image. Usually, the photographer checks the subject image with the viewfinder and adjusts the focus. Or take a picture.

  The viewfinder of such an imaging device is usually small in size, and due to technical difficulties and costs, a display device that can handle only a video signal that is lower in definition than a video signal that the imaging device can shoot is used. There is. For example, when a lower-definition liquid crystal monitor is used as a viewfinder of a high-vision camera.

  In such a case, the video signal obtained from the normal image sensor is displayed on the viewfinder and the liquid crystal monitor after the format conversion process (down-conversion process) is performed on the video signal that can be handled by the viewfinder. In addition, format conversion processing for display on a viewfinder, LCD monitor, etc., often uses simple processing, and focus adjustment of high-definition video while checking low-definition video that has been easily created As a result, the focus adjustment is very difficult.

  Japanese Patent Application Laid-Open Publication No. 2005-133867 discloses an enlargement display device that enables high-definition display on a display device that can handle a high-definition video signal only with a lower-definition video signal. In this method, a part of a high-definition video signal is extracted and displayed on a display device that can handle only a low-definition video signal. If this conventional enlarged display device is applied to the viewfinder of an imaging device, an imaging device that can easily perform focus adjustment by performing high-definition enlarged display on a low-definition display device when performing focus adjustment. realizable.

  FIG. 7 is a block diagram showing the configuration of the enlarged display device of Patent Document 1. In FIG. 7, 1 is a format converting means for converting a high-definition photographed video signal into a low-definition video signal that can be supported by a display device, and 2 is a clock conversion by extracting a part of the high-definition photographed video signal. Thus, the focus confirmation video creating means for outputting the focus confirmation enlarged video, 3 is the video data to be output to the display device by combining or switching the low-definition whole video for angle of view confirmation and the focus confirmation enlarged video. It is a composition switching means.

  The operation of the conventional enlarged display device configured as described above will be described.

  At the time of normal shooting, a low-definition whole image for angle of view confirmation obtained by converting the format of a high-definition captured image signal by the format conversion means 1 is output as a viewfinder image signal. At the time of focus adjustment, a user or the like gives an instruction using an external switch or the like. An instruction at the time of focus adjustment is input to the video data composition switching means 3. The focus confirmation video creation means 2 creates a focus confirmation enlarged video by simply cutting out a part of the video data of the input high-definition captured video signal. The video data composition switching means 3 synthesizes and outputs the enlarged image for focusing confirmation with the low-definition whole picture for angle of view confirmation, for example.

  FIG. 8 is a schematic diagram for explaining an output image of a conventional enlarged display device. In FIG. 8, (a) is a high-definition captured video signal, (b) is a normal output video, a low-definition overall video for viewing angle confirmation, (c) is an output at the time of focus assist, An enlarged image for in-focus confirmation shows an image synthesized with a low-definition whole image for angle of view confirmation.

  This will be described in more detail with reference to FIG.

  The input high-definition captured video signal (a) originally contains fine noise components such as random noise. Since the format conversion process is usually realized by performing an interpolation process by general filtering or the like, the low-definition whole video for angle-of-view confirmation also reduces video noise at the same time during the format conversion process. In addition, since the format conversion process for display is often simply configured, not only noise components but also high-frequency components of video signals are often reduced. Accordingly, the low-definition whole image for angle-of-view confirmation in FIG. 8B is a blurred image signal with less noise. On the other hand, the enlarged image for focusing confirmation is created by extracting a part of the high-definition captured video signal by the focusing confirmation image creating means 2, so that the noise component of the original image is not reduced. It will be converted to a low frequency band, resulting in a very noticeable image. Therefore, as shown in FIG. 8C, in the synthesized video, noise is conspicuous only in the enlarged video portion, and the peripheral video becomes a blurred video signal with little noise, which is very uncomfortable.

Further, there is an image pickup apparatus described in Japanese Patent Application Laid-Open No. 2004-151561 that allows confirmation of focusing even with a relatively small display apparatus. In a digital still camera equipped with a two-stroke type shutter release button, the entire image for normal angle of view confirmation is displayed, and when the shutter release button is pressed halfway, an enlarged image is displayed. This makes it easy to check the in-focus state. In addition, when the shutter release button is pressed, an image in which an in-focus confirmation enlarged screen is inserted into an image for confirming the angle of view, an enlarged image at a plurality of different positions, or a plurality of different images are displayed. By displaying an image enlarged at an enlargement magnification of, or displaying an image in which an image enlarged at a different position is displayed, the in-focus state can be easily confirmed.
JP 2001-67061 A JP 2001-212351 A

  However, in an imaging device in which the above-described conventional enlarged display device is applied to a viewfinder or an imaging device that enables confirmation of focus even with a relatively small display device, an image displayed at the time of focus adjustment However, there is a problem that it becomes a very uncomfortable image by synthesizing an enlarged image with noticeable noise and a blurred peripheral image with little noise.

  Further, in an imaging device in which a conventional enlarged display device is applied to a viewfinder or an imaging device that enables confirmation of in-focus even with a relatively small display device, video signal selection is performed by, for example, a shutter- Since an instruction from the user or the like is required by an external switch in which the release button is half-pressed, an extra operation is necessary for focus adjustment.

  In addition, in an imaging device in which a conventional enlarged display device is applied to a viewfinder, or an imaging device that enables confirmation of focus even with a relatively small display device, the control is performed regardless of the zoom position. Therefore, at the wide end (most wide-angle side of zoom), the enlarged image for focusing confirmation is blurred, and at the tele end (most telephoto side of zoom), noise components remain in the enlarged image for focusing confirmation. Had a point.

  The present invention solves the above-mentioned conventional problems, and reduces the image quality difference between the enlarged image for focus confirmation and the low-definition whole image for angle of view confirmation by individually reducing the noise of the enlarged image for focusing confirmation. An object of the present invention is to reduce the uncomfortable feeling that images of different image quality are synthesized during the focusing operation and to improve the quality of the focus assist function.

  It is another object of the present invention to automatically perform switching control between an in-focus confirmation enlarged image and an angle-of-view low-definition whole image depending on whether or not the focus ring is turned, thereby improving the focus adjustment operability.

  It is another object of the present invention to improve the quality of the focus assist function at all zoom positions by obtaining an enlarged image for focusing confirmation adapted to optical zoom.

According to the first aspect of the present invention, there is provided a video signal format conversion means, a focus confirmation video creation means, a noise reduction means, a focus confirmation enlarged video, and a low-definition overall video for angle of view confirmation. Video data composition switching means for combining or switching,
By individually performing image quality improvement processing on the in-focus confirmation enlarged image, it is possible to suppress a sense of incongruity in the synthesis or switching image of the in-focus confirmation enlarged image and the low-definition whole image for angle of view confirmation.

According to a fifth aspect of the present invention, there is provided a video signal format conversion means, a focus confirmation video creation means, a noise reduction means, a focus confirmation enlarged video, and an angle confirmation low-definition whole video. Video data composition switching means for combining or switching; focus confirmation video creation means; noise reduction means; and focus assist control means for controlling operations of the video data composition switching means,
Depending on whether the focus ring is turned, the focus assist control means automatically performs switching control between an in-focus confirmation enlarged image and an angle-of-view confirmation low-definition whole image, thereby improving the focus adjustment operability. It has the action.

According to a sixth aspect of the present invention, there is provided a video signal format conversion means, a focus confirmation video creation means, a noise reduction means, a focus confirmation enlarged video, and an angle confirmation low-definition whole video. Video data composition switching means for combining or switching; focus confirmation video creation means; noise reduction means; and focus assist control means for controlling operations of the video data composition switching means,
The focus assist control means has an effect that the quality of the focus assist function can be improved at all zoom positions by switching the enlargement magnification of the enlarged image for focusing confirmation and the noise reduction effect according to the zoom position.

  As described above, the present invention can suppress a sense of incongruity due to the difference in image quality between the low-definition whole image for checking the angle of view and the enlarged image for checking the focus by format conversion. It is done.

  In addition, as described above, the present invention can detect when the focus is adjusted by the operation of the focus ring, and can automatically switch between the enlarged image for focus confirmation and the low-definition whole image for angle of view confirmation. An excellent effect that can be carried out without increasing the labor of is obtained.

  In addition, as described above, the present invention provides an excellent effect of improving the quality of the focus assist function at all zoom positions by switching the magnification and noise reduction characteristics adapted to the zoom positions.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of a focus assist function unit of an imaging apparatus with a focus assist function according to Embodiment 1 of the present invention.

  In FIG. 1, 1 is a format conversion means for converting a high-definition captured video signal into a low-definition video signal that can be handled by a display device, and 2 is a clock conversion performed by extracting a part of the high-definition captured video signal. And a focus confirmation video creation means for converting into a displayable video signal, and 3 for synthesizing or switching the low-definition overall video for angle of view confirmation and the enlarged video for focus confirmation and outputting to the display device. Means 4 are noise reduction means for performing image quality improvement processing only on the enlarged image for focus confirmation.

  The imaging apparatus with a focus assist function according to the present embodiment has a configuration in which noise reduction means 4 is added to the output of the focus confirmation video creation means 2 in the configuration of the conventional enlarged display device.

  FIG. 2 is a schematic diagram for explaining the output video of the imaging apparatus with a focus assist function according to the present embodiment, which is the same as FIG. 8 for explaining the output video of the conventional enlarged display device.

  A state of operation of the imaging apparatus with a focus assist function configured as described above will be described in detail with reference to FIGS.

  At the time of normal shooting, a low-definition whole image for angle of view confirmation obtained by converting the format of a high-definition captured image signal by the format conversion means 1 is output as a viewfinder image signal. At the time of focus adjustment, a user or the like generates an instruction using an external switch (not shown) or the like. An instruction at the time of focus adjustment is input to the video data composition switching means 3. The focus confirmation video creation means 2 writes a part of the video data of the input high-definition captured video signal to a storage device (not shown) such as a memory with a clock in the high-definition captured video format for display. By reading out with the clock in the video format of the apparatus, the video is simply cut out and an enlarged image for focusing confirmation is created. The noise reduction unit 4 performs, for example, horizontal low-pass filter processing to such an extent that the noise component of the enlarged image for focusing confirmation is not noticeable. That is, since only noise in the enlarged image for focusing confirmation in FIG. 2C is reduced, it is possible to suppress a sense of discomfort in the synthesized image. The noise reduction characteristics are adjusted manually while viewing the enlarged image. For example, in the case of performing the horizontal low-pass filter processing, the frequency characteristics of the horizontal low-pass filter are experimentally changed while viewing the enlarged image, and adjusted so that the noise component of the enlarged image is not noticeable. The frequency characteristics of the horizontal low-pass filter may be basically fixed, but a plurality of frequency characteristics may be prepared so that the user can switch them using a menu or the like.

  What should be noted here is that noise reduction processing individually adjusted for the in-focus confirmation enlarged image is performed. That is, if the effect of the noise reduction process is too great, the enlarged image is too blurred and cannot be used for focus adjustment. If the effect of the noise reduction process is too small, the noise is noticeable and a sense of incongruity occurs as in the conventional case. .

  The video data composition switching means 3 synthesizes and outputs a focus confirmation enlarged video with a reduced noise to a low-definition overall video for angle-of-view confirmation, for example.

  As described above, the present invention can suppress a sense of incongruity due to the difference in image quality between the low-definition whole image for checking the angle of view and the enlarged image for checking the focus by format conversion. It is done.

  In the first embodiment, the noise reduction unit 4 does not need to be a low-pass filter process in the horizontal direction, and may be a coring process. FIG. 3A shows a block diagram of the coring process. Input video is input to mutually exclusive low-pass filter 101 and high-pass filter 102, and the output of high-pass filter 102 is input to coring characteristic performing means 103. The coring characteristic implementing means 103 performs nonlinear processing indicated by the input / output characteristics in the coring processing of FIG. 3B, and deletes the high frequency component having a low level. The output of the coring characteristic implementing means 103 and the output of the low pass filter 101 are added and output. That is, noise reduction is realized by considering low frequency components of high frequency components as noise and removing them. Therefore, when the coring amount shown in FIG. 3B is increased, the noise reduction effect is increased. Conversely, when the coring amount is decreased, the noise reduction effect is decreased. Adjust the coring amount to an appropriate amount while observing the reduction effect. Alternatively, two-dimensional filtering processing may be used, or two-dimensional correlation may be investigated and filtering processing may be performed in the direction of strong correlation. After suppressing high frequency components of digital data with a low-pass filter, a slightly lower frequency component may be used. The image quality of only the enlarged image for focusing confirmation is adjusted so that there is no sense of incongruity due to the difference in image quality between the low-definition whole image for viewing angle confirmation and the enlarged video for focusing confirmation by format conversion. Anything to do.

  In the first embodiment described above, the instruction at the time of focus adjustment is input only to the video data composition switching means 3, but it is also input to the focus confirmation video creation means 2 and the noise reduction means 4 to adjust the focus. Otherwise, the operation may be stopped.

(Embodiment 2)
FIG. 4 is a block diagram showing the configuration of the focus assist function unit of the imaging apparatus with a focus assist function according to the second embodiment of the present invention.

  In FIG. 4, 1 is a format conversion means for converting a high-definition captured video signal into a low-definition video signal that can be supported by the display device, and 2 is a clock conversion performed by extracting a part of the high-definition captured video signal. A focus confirmation video creating means for performing and converting into a displayable video signal; 3, a video data composition switching means for synthesizing or switching the low-definition overall video for angle of view confirmation and the enlarged video for focus confirmation and outputting to the display device Reference numeral 4 denotes noise reduction means for performing image quality improvement processing only on the in-focus confirmation enlarged image. Reference numeral 5 denotes focus assist control means for controlling the focus assist operation according to the state of the image pickup apparatus. In FIG. The operation state of the ring is detected, and the composition switching operation in the video data composition switching means is automatically controlled.

  The focus assist function unit configured as described above is different from the above-described first embodiment in that the addition of the focus assist control means 5 makes it possible to synthesize video data depending on the operating state of a focus ring (not shown). This is where the composition switching operation in the switching means is controlled.

  The other components are the same as those in the first embodiment, and for the sake of simplification, only the operation of the different focus assist control means 5 will be described in detail.

  The focus assist control means 5 always monitors the focus position of the imaging device. For example, a method such as periodically AD converting the voltage for the focus position of the lens with a microcomputer or obtaining information from the lens by serial communication is used. By monitoring the focus position, it is determined whether the focus lens is turned or not. When the focus lens is turned, an enlarged image for focusing confirmation is output, and when it is not turned, a normal low-definition whole image for angle of view confirmation is output.

  That is, it automatically determines when the user is turning the focus ring when adjusting the focus, and when the focus ring is stopped when it is normal, and controls the switching operation of the video signal for the viewfinder.

  An important effect different from that of the first embodiment is that the switching means of the focus confirmation enlarged image is controlled by whether or not the focus ring is turned, so that the switching operation at the time of focus adjustment is instructed by an external means such as a switch. There is no need to do that.

  As described above, the present invention can detect when the focus is adjusted by the operation of the focus ring, and can automatically switch between the enlarged image for focus confirmation and the entire low-definition image for angle of view confirmation. The excellent effect which can be implemented without increasing labor is obtained.

(Embodiment 3)
FIG. 5 is a block diagram showing the configuration of the focus assist function unit of the imaging apparatus with a focus assist function according to the third embodiment of the present invention.

  In FIG. 5, 1 is a format conversion means for converting a high-definition captured video signal into a low-definition video signal that can be supported by the display device, and 2 is a clock conversion by extracting a part of the high-definition captured video signal. A focus confirmation video creating means for performing and converting into a displayable video signal; 3, a video data composition switching means for synthesizing or switching the low-definition overall video for angle of view confirmation and the enlarged video for focus confirmation and outputting to the display device Reference numeral 4 denotes noise reduction means for performing image quality improvement processing only on the enlarged image for in-focus confirmation. Reference numeral 5 denotes focus assist control means for controlling the focus assist operation depending on the state of the image pickup apparatus. In FIG. Focus assist control means for detecting the position and adaptively controlling the enlargement magnification in the focus confirmation video creation means and the noise reduction characteristics in the noise reduction means.

  Regarding the focus assist function unit configured as described above, the difference between the first embodiment and the second embodiment described above is that the focus assist control means 5 is an enlargement magnification in the enlarged image creation means for focusing confirmation according to the zoom position. This is where the noise reduction characteristics of the noise reduction means are controlled.

  The other components are the same as those in the first and second embodiments, and the operation of the different focus assist control means 5 will be described in detail for the sake of simplicity.

  As in the second embodiment, the focus assist control unit 5 always monitors the zoom position and discriminates between the tele end and the wide end.

  In the case of the tele end, the enlargement magnification in the in-focus confirmation enlarged image creating means is set to 1 and the noise reduction effect in the noise reducing means is largely controlled. In the case of the wide end, the enlargement magnification in the in-focus confirmation enlarged image creating means is larger than 1, and the noise reduction effect in the noise reducing means is controlled to be small.

  For example, the focus confirmation video creation means 2 writes part of the video data of the input high-definition captured video signal into a storage device such as a memory with a clock in the high-definition captured video format, and displays the video on the display device. By reading out with the clock in the format, it is possible to realize a 1 × video cut-out operation. Similarly, by extracting the same data twice with the clock in the video format of the display device, it is possible to realize a video segmenting operation that has been doubled.

  An important effect different from the first and second embodiments described above is that the video signal itself often has a fine picture at the wide end, so that the enlargement magnification of the enlarged image for focusing confirmation is greatly controlled, Since there are many high-frequency components in the signal component of the enlarged image, the focus adjustment can be made easier by controlling the noise reduction effect to be small. In addition, since it is optically enlarged at the telephoto end, the enlargement magnification of the in-focus confirmation enlarged image is controlled to 1 time, and since the high-frequency component is small in the signal component of the enlarged image, the noise reduction effect is greatly controlled. As a result, it is possible to obtain a composite image with less discomfort.

  As described above, in the present embodiment, by automatically switching the enlargement magnification of the in-focus confirmation enlarged image and the noise reduction effect according to the zoom position, the focus adjustment can be more easily realized in a fine pattern, and the optical In the case of an enlarged image, it is possible to obtain an excellent effect of simultaneously obtaining an enlarged image for focusing confirmation with less discomfort.

  In Embodiment 3 described above, the case of switching between the tele end and the wide end has been described. However, the present invention is not limited to this, and the tele end and the wide end are divided into a plurality of areas and switched respectively. Control may be performed.

  Since the second embodiment and the third embodiment described above can be realized simultaneously, a block diagram showing the configuration is shown in FIG. Since the operation is exactly the same as described above, a description thereof will be omitted.

  The third embodiment has been described on the assumption that the format of the high-definition captured video signal and the format of the viewfinder video signal are unchanged. However, there are cases where the video signal format for the viewfinder can be changed, such as in the case of a multi-format imaging device or a display device with both a viewfinder and a liquid crystal monitor with different formats. It is desirable to switch and control the enlargement control signal and the noise reduction control signal in consideration of the format format.

  The image pickup apparatus according to the present invention can display an enlarged image for focus adjustment without a sense of incongruity when shooting a high-definition video signal while confirming with a display device that can handle only a low-definition video signal. Therefore, it is useful as an imaging device such as a video camera or a still camera.

  In addition, the imaging apparatus according to the present invention automatically captures an enlarged image for focus adjustment only by turning the focus ring when shooting a high-definition video signal while confirming with a display device that can handle only a low-definition video signal. Since it can be displayed, it has an effect of improving the operability of focus adjustment, and is useful as an imaging device such as a video camera or a still camera.

  The image pickup apparatus according to the present invention adjusts the image quality of an enlarged image for focus adjustment according to a zoom position when shooting a high-definition video signal while confirming with a display device that can handle only a low-definition video signal. Thus, since an optimal enlarged image can be obtained from the wide end to the tele end, it has an effect of improving the operability of the focus adjustment, and is useful as an imaging device such as a video camera or a still camera.

1 is a block diagram showing a configuration of a focus assist function unit according to Embodiment 1 of the present invention. Schematic diagram for explaining an output video according to the first embodiment of the present invention. Schematic diagram for explaining a specific example of noise reduction means according to the first embodiment of the present invention. The block diagram which shows the structure of the focus assist function part by Embodiment 2 of this invention. The block diagram which shows the structure of the focus assist function part by Embodiment 3 of this invention. The block diagram which shows the structure of the focus assist function part which implement | achieved Embodiment 2 and Embodiment 3 of this invention simultaneously. Block diagram showing the configuration of a conventional enlarged display device Schematic diagram for explaining the output video of a conventional enlarged display device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Format conversion means 2 Focus confirmation video creation means 3 Video data composition switching means 4 Noise reduction means 5 Focus assist control means 101 Low pass filter means 102 High pass filter means 103 Coring characteristic implementation means

Claims (7)

Format conversion means for outputting a high-definition video signal to a display device that can handle only a lower-definition video signal; focus confirmation video creation means for creating a focus confirmation video from the high-definition video signal; Noise reduction means for performing image quality improvement processing only on the focus confirmation video, and video data composition switching means for synthesizing or switching the focus confirmation video after the image quality improvement processing and the entire angle confirmation video. An imaging apparatus with a focus assist function, comprising: The imaging apparatus with a focus assist function according to claim 1, wherein the noise reduction unit varies a frequency characteristic of an in-focus confirmation video. The imaging apparatus with a focus assist function according to claim 1, wherein the noise reduction unit performs a coring process on an in-focus confirmation image. 2. The imaging apparatus with a focus assist function according to claim 1, further comprising focus assist control means for controlling operations of a focus confirmation video creating means, a noise reduction means, and a video data composition switching means. 5. The focus assist according to claim 4, wherein the focus assist control means detects whether or not the focus ring is turned, and synthesizes or switches the focus confirmation video and the view angle confirmation whole video. Imaging device with function. 5. The image pickup apparatus with a focus assist function according to claim 4, wherein the focus assist control means switches an enlargement magnification and a noise reduction effect of the focus confirmation video according to a zoom position. 7. The imaging apparatus with a focus assist function according to claim 6, wherein the focus assist control means switches noise reduction characteristics in the noise reduction means according to a high-definition video signal format and a viewfinder video signal format.

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