JP2010091669A - Imaging device - Google Patents

Abstract

An imaging apparatus capable of easily confirming an in-focus subject using a low-resolution viewfinder, a display, or the like.
A subject is extracted according to a distance based on distance information of the subject. Also, focus information is calculated based on the focal length and the aperture value of the aperture obtained from the position of the focusing lens. Then, an image of the subject is displayed on the display screen 10. Further, a subject distance graph in which focus information is added to a subject position mark indicating the position of the subject is displayed on a graph with the distance as an axis. As a result, it is possible to easily confirm whether or not a plurality of subjects within the photographing range exist within the focusing range.
[Selection] Figure 2

Description

  The present invention relates to an imaging apparatus, and more particularly to a technique for displaying a subject position, focus information, and the like during shooting.

  In recent years, as represented by high vision, the resolution of images has been increasing, and accordingly, there has been an increasing demand for focusing accurately when shooting. However, it is difficult to increase the resolution of display images mounted on camera viewfinders, digital still cameras, digital single lens reflex cameras, and the like due to physical limitations.

  Therefore, Patent Document 1 discloses a method of calculating the focus position and the depth of field from the position of the focus lens of the camera and the F value of the aperture and presenting it to the photographer in order to focus accurately even at a low resolution. Has been.

  Patent Document 2 proposes a method for displaying a focused object in a different color using a focus position and a depth of field, and a distance image obtained by a distance image sensor or the like and camera focus information. Yes.

Here, the distance image sensor is a distance measuring sensor that can capture a target space and obtain the distance to the target existing in the target space in units of pixels, and an image obtained by this sensor is called a distance image. . In Patent Document 3, as a distance image sensor method, a surface of a measurement object is scanned with a light beam, and a distance to a displacement surface displaced by scanning from the reference surface of the measurement object is measured by a triangulation method. Proposed.
JP-A-8-220419 JP 2007-86481 A JP-A-9-257418

  In the methods of Patent Documents 1 and 2, since only the in-focus distance and the depth of field are displayed, it is possible to check which subject is in focus within the shooting range using a low-resolution viewfinder or display. Hateful.

  An object of the present invention is to provide an imaging apparatus capable of easily confirming a focused subject using a low-resolution viewfinder, a display, or the like.

  The present invention provides an imaging device for photographing a subject, a means for detecting distance information of the subject, a means for extracting the subject according to the distance based on the distance information, a focal length obtained from the position of the focusing lens, and Means for calculating focus information based on the aperture value of the aperture; and the subject created on the basis of the extracted subject displayed on the display screen on the graph with the subject image and the distance as an axis Display means for displaying a subject distance graph in which the focus information is added to a subject position mark indicating the position of the subject.

  According to the present invention, even in a low-resolution viewfinder, display, or the like, it is possible to easily confirm whether or not a plurality of subjects within the shooting range are within the focusing range.

  Next, the best mode for carrying out the invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of an imaging apparatus according to the present invention. In the figure, reference numeral 1 denotes a lens system that includes a zoom lens for zooming, a focusing lens for focusing the image pickup device 2, and a diaphragm for adjusting the aperture. The zoom lens and the focusing lens can be moved separately in the optical axis direction by a driving means (not shown). The aperture can also be adjusted by driving means (not shown).

  4 is a zoom magnification calculation circuit that detects the position of the zoom lens and calculates the zoom magnification, 5 is an F value detection circuit that detects the F value of the stop, and 6 is a focal length that calculates the focal length from the position of the focusing lens. It is a calculation circuit. Reference numeral 2 denotes an image sensor. The imaging element 2 photoelectrically converts the subject image formed on the imaging surface by the lens system 1 and converts it into an imaging signal. A CCD, CMOS, or the like is used for the image sensor 2.

  The camera signal processing circuit 3 is a circuit that generates a luminance signal and a color signal from the imaging signal output from the imaging device 2 and performs signal processing such as color correction and gamma correction. A distance image sensor 7 generates a distance image. Reference numeral 8 denotes a subject distance graph creation circuit that obtains camera information from the zoom magnification detection circuit 4, F value detection circuit 5, and focal length calculation circuit 6 and distance image information from the distance image sensor to create a subject distance graph.

  The subject distance graph creation circuit 8 combines the camera information and the distance image information, and generates a subject distance graph in which a plurality of subject position marks and focus information indicating the positions of a plurality of subjects are added on the graph with the distance as an axis. The image synthesis circuit 9 generates an image obtained by OSD (On Screen Display) display of the subject distance graph for the subject image obtained from the camera signal processing circuit 3 and displays the generated image on the display device 10. In FIG. 1, a controller for controlling each part in the apparatus such as the lens system 1 and the image sensor 2 is omitted.

  FIG. 2 is a diagram for explaining an example of the distance information display method according to the present invention. FIG. 2 shows an example of distance information displayed on the display screen of the display device 10 of FIG. FIG. 3 is a diagram showing the distance relationship between the subject and the camera in FIG. Here, as an example, as shown in FIG. 3, it is assumed that a person is present at a position 5 m away from the camera and an object is present at a position 8 m away from the camera. In FIG. 3, it is assumed that the person is in focus, DOFf represents the front depth of field, and DOFb represents the rear depth of field.

  In FIG. 1, the display device 10 displays a subject image and a subject distance graph. As shown in FIG. 2, a subject distance graph indicating the subject position, focus position, and depth of field is displayed together with the subject image on the distance axis 15 indicating the distance on the display device 10 using the subject distance information and the focus information. .

  Next, a display example of the subject distance graph will be described. 2 in FIG. 2 is a depth-of-field band representing the depth of field on the subject distance graph. In this example, since an object and a person are within the shooting range as subjects, subject position marks 12 and 13 indicating their positions are displayed.

  The display of the subject position mark changes according to the size of the subject. For example, when the subject position mark is expressed using a bar as shown in the figure, the height and width of the bar are adjusted in proportion to the actual height and depth of the subject. That is, since the size of the bar on the subject distance graph changes in proportion to the actual size of the subject, it is easy to take correspondence between the subject in the subject image and the subject position mark on the subject distance graph.

  Further, a focus position mark 14 indicating the focus position is also displayed on the subject distance graph. By displaying the subject image and the subject distance graph as described above, since the focus position mark 14 is displayed at the distance indicated by the subject position mark 13 of the person, the user can know at a glance that the person is in focus. Further, since the subject position mark 12 of the object is out of the depth-of-field band 11, it is possible to know that the object is not in focus. Therefore, even in a low-resolution viewfinder, display, or the like, it is possible to easily confirm whether or not a plurality of subjects within the shooting range are within the focusing range.

  Next, a processing procedure when performing shooting according to the present embodiment will be described with reference to FIG. FIG. 4 is a flowchart showing a flow of a processing procedure at the time of photographing. First, when the user presses a subject distance graph display button (not shown) at the start of photographing (S101), the subject distance graph creation circuit 8 performs subject distance graph creation processing (S102). Details of the processing for creating the subject distance graph will be described later.

  Next, the image synthesizing circuit 9 creates an image obtained by synthesizing the created subject distance graph and the subject image (S103), and displays the synthesized image on the display device 10 (S104). When the user presses a shutter button (not shown) halfway (S105), the focusing lens in the lens system 1 is moved under the control of a controller (not shown) to automatically focus on one of the subjects within the shooting range. (S106). At this time, it is assumed that the subject to be focused is determined in advance in the subject distance graph creation processing in S102. If the half-press of the shutter button is not released (S107) and the shutter button is fully pressed (S108), shooting is performed (S109) and the shooting is terminated.

  In S107, when the half-press of the shutter button is released because the subject desired by the user is out of focus or the like, the user changes the focus to focus on another subject within the shooting range ( S110). When the focus is changed, the subject distance graph creation process of S102 is performed again to update the subject distance graph. Here, when the half-press of the shutter button is released, the focus of the lens system 1 is adjusted so that a plurality of subjects within the shooting range are in focus instead of changing the focus to another subject. The aperture may be adjusted.

  With the above processing, the user can focus on the desired subject by repeating half-pressing and releasing the half-pressing of the shutter button, and then the user can focus on the desired subject by pressing the shutter button fully. An image can be taken. Further, when changing the focus, the focus may be switched in order from the subject closest to the imaging device, or conversely, the focus may be switched in order from the subject far from the imaging device. In addition, a person's face may be recognized, and the focus may be sequentially switched to only a subject that has been identified as a human subject, or a plurality of human subjects may be within the depth of field. The display of the subject distance graph when the face of a person is recognized will be described later.

  Next, an overall processing procedure for creating a subject distance graph (processing in S102 of FIG. 4) will be described with reference to FIG. When the creation of the subject distance graph is started, first, the subject distance graph creation circuit 8 acquires distance image information from the distance image sensor 7 in S201, and extracts a subject using the distance image information in S202. With the procedure so far, the distance for each subject in the image can be obtained.

  In step S203, the subject distance graph creation circuit 8 measures the size of the subject extracted in step S202. In S204, camera information including the in-focus distance, the focal length, and the F value is acquired from the zoom magnification detection circuit 4, the F value detection circuit 5, and the focal length calculation circuit 6, and in S205, the focus position, Calculate the depth of field. Thereafter, the scale of the distance axis of the subject distance graph is determined on the basis of the subject distance, the focus position, etc. found in S206. Finally, in S207, the subject distance graph is created from the information obtained so far.

  Next, details of processing in each procedure of FIG. 5 will be described. Regarding the acquisition of the distance image information in S201 of FIG. 5, the distance image information obtained by the distance image sensor 7 is acquired. Here, the distance image is an image as shown in FIG. 6 taking the same shooting target space as described in FIG. Since the luminance value of each pixel is replaced with a distance value, an image whose luminance value changes according to the distance is obtained. In this example, when the color is black, it is closer to the camera (imaging device), and as the color becomes white, the camera is further away from the camera.

  If this distance image is used, it is possible to extract a subject according to each distance. Therefore, in S202 of FIG. 5, the subject is extracted based on this distance image. Taking FIG. 2 and FIG. 3 as an example, a set of continuous pixels having a distance value of 5 m from the camera is regarded as one subject and extracted. However, since the subject has irregularities, not only pixels with a distance value of 5 m are extracted, but pixels with a distance value of around 5 m are extracted. A value is set in advance, and consecutive pixels around 5 m from the set value are determined as pixels corresponding to the subject.

  For example, if the set value is s [m], continuous pixels having distance values of (5-s) to (5 + s) [m] are extracted. In the present embodiment, a subject having a distance value of 5 m corresponds to a person, and an image as shown in FIG. 7 can be extracted. In the same way, a subject (object) existing behind a person having a distance value of 8 m is extracted.

  At this time, the focusing lens in the lens system 1 in FIG. 1 is moved so that one of the extracted subjects is in focus. The subject to be focused on may be the subject closest to the imaging device, the farthest subject, the subject existing in the center of the shooting range, the subject with the largest number of pixels in the subject image, or the like. In these cases, the user may select a subject to be focused preferentially by changing the setting of the imaging apparatus.

  When the extraction of the subject is completed, the actual size of the subject extracted in S203 of FIG. 5 is measured. In the present embodiment, the height and depth of the subject are used when creating the graph. First, a method for obtaining the height of a subject will be described with reference to FIG. In the figure, a is the focal length, b is the height of the subject image projected on the image sensor, c is the distance from the camera to the subject, and x is the height of the subject to be obtained. The relationship between these distance values can be expressed as in equation (1).

  The focal length a can be calculated by detecting the position of the focusing lens by the focal length calculation circuit 6 and the detection result. The height b of the subject image depends on the number of pixels of the subject image formed on the image sensor 2. Can be calculated. Specifically, it is obtained by multiplying the size per pixel of the image sensor 2 by the number of pixels occupied by the subject. The distance c can be obtained from a distance image. In order to obtain x using these three values, it can be obtained by Expression (2) obtained by modifying Expression (1).

b / a = x / c Formula (1)
x = bc / a Formula (2)
The depth dimension of the subject is also calculated using the distance image. First, the difference between the maximum value and the minimum value of the extracted distance values of the subject is calculated. Since this difference is the depth only in front of the subject, the depth dimension is a value obtained by doubling the difference calculated in consideration of the depth behind the subject. Regarding the dimensions behind the subject, the depth dimension may be calculated by holding various object shapes as a database and predicting the rear of the subject based on the database.

  In addition, the depth dimension may be calculated by applying to a basic figure (a sphere, a cylinder, a quadrangular prism, etc.) from the unevenness of the subject surface that can be seen from the distance image. Furthermore, when it is determined that the subject is a person by recognizing a person's face, the depth dimension may be set in consideration of a standard human figure. The display of the subject distance graph when the face of a person is recognized will be described later.

  In S204 of FIG. 5, as described above, the zoom magnification is obtained from the zoom magnification calculation circuit 4, the F value is obtained from the F value detection circuit 5, and the focal length is obtained from the focal length calculation circuit 6 as camera information. In S205 of FIG. 5, the focus position and the depth of field are calculated based on the camera information acquired in S204. The focus position is calculated from the focal length. For the depth of field, the front depth of field DOFf and the rear depth of field DOFb are calculated from the zoom magnification and the F value. When there is no zoom function, it is calculated from the F value.

  Next, in S206 of FIG. 5, the scale of the distance axis is determined based on the subject distance. As a method of determining the scale, the scale is determined so that the closest subject and the farthest subject are within the range among the extracted subjects. By doing so, it is possible to display so that all the extracted subjects fall within the distance axis. For example, when the subject exists at the positions of 1 m, 5 m, and 9 m, the scale of the axis is determined so that all the position marks of the subject that can be extracted in the subject distance graph are accommodated as shown in FIG.

  When determining the scale of the distance axis, a margin of 1 m is given to the scale in consideration of the bar width of the subject position mark. In the example of FIG. 9, the minimum value of the distance axis is set to 0 m instead of 1 m, and the maximum value is set to 10 m instead of 9 m. The display range may be specified by the user.

  Finally, in S207 of FIG. 5, a subject distance graph is created based on the information acquired and calculated so far. At this time, the height and width of the bar of the subject position mark are adjusted according to the height and depth of the subject based on the scale of the distance axis determined in S206 of FIG. As shown in FIG. 10, the size of the subject position mark 13 is determined so that the height of the subject corresponds to the height h of the subject position mark 13 and the depth of the subject corresponds to the width d of the subject position mark 13.

  Specifically, if the scale of the distance axis determined in S206 in FIG. 5 corresponds to 1 m for 50 pixels in the display device, for example, and the actual size of the subject is 1.7 m in height and 0.2 m in depth, h is 50 × 1.7 = 85 pixels, and d is 50 × 0.2 = 10 pixels. When the size of the subject position mark is determined, the subject position mark is arranged on the distance axis based on the subject distance obtained from the distance image.

  Further, the focus position, the front depth of field and the rear depth of field calculated in S205 of FIG. 5 are combined with the subject position mark and the focus position mark and the depth of field band are used by matching the distance axis. indicate. Further, an arrow A in FIG. 5 indicates a processing start position when processing from S110 in FIG. 4 is entered. If there is no change in the shooting range, the subject size and subject distance do not change, so only the process related to the camera information changed by the focus change in S110 in FIG. 4 is performed.

  Recently, many techniques related to face recognition have been proposed, such as recognizing a person's face and preferentially focusing on the person's face. In this regard, in the present invention, when a human subject can be recognized using the face recognition technology, it is possible to provide a mode for highlighting a subject position mark corresponding to a person.

  Specifically, when the mode for emphasizing a person subject is ON, only the subject position mark of the person is displayed as shown in FIG. 11, and the subject position marks other than the person are not displayed. Furthermore, in the present invention, as shown in FIG. 12, the subject existing within the depth of field may be highlighted by edge enhancement in the subject image.

  In addition, this invention is not limited to embodiment mentioned above, Various application is possible in the range which does not deviate from a summary. For example, in the above embodiment, the subject distance information is obtained using a distance image sensor, but the subject distance is obtained by sequentially examining the distance at which the subject is focused while moving the focusing lens of the camera. Also good. In this case, the property that the high frequency spatial frequency component of the image output signal increases when the image is in focus is used.

  As a method for determining the scale of the distance axis, the scale is determined so that the distance range specified by the user is within the focus position, or the scale is determined so that the depth of field is within the display range. May be.

  Although the focus position mark is used to indicate the focus position, the focus position is displayed by changing the color of the subject position mark of the subject that is in focus from the other subject position marks. Also good.

  Furthermore, the subject position mark is displayed using a bar, but other shapes may be used as the mark, and the actual subject unevenness is also reflected in the subject position mark. Also good.

  With respect to the highlight display of the subject within the depth of field in the subject image, the subject within the depth of field may be enclosed and displayed as shown in FIG.

  As for the highlighted display of the person's subject position mark, as shown in FIG. 14A, the person's subject position mark may be highlighted with a different color from the subject position marks of other persons. In addition, as shown in FIG. 14 (b), highlighting may be performed by displaying a mark indicating a person in the subject position mark of the person. Here, the positional relationship of the subject in FIG. 14 is the same as that in FIG.

  Regarding the display of the distance graph, the display screen of the display device is divided as shown in FIG. 15 instead of the OSD display on the subject image, and the subject image is displayed on one screen and the subject distance graph is displayed on the other screen. May be.

It is a block diagram which shows the structure of one Embodiment of the imaging device which concerns on this invention. It is a figure explaining an example of the distance information display which concerns on this invention. It is a figure which shows the distance relationship between a camera and a to-be-photographed object. It is a flowchart which shows the flow of the process sequence at the time of imaging | photography concerning this invention. It is a flowchart which shows the flow of the preparation procedure of the to-be-photographed object distance graph which concerns on this invention. It is a figure which shows an example of a distance image. It is a figure which shows an example of the to-be-photographed object extracted from the distance image. It is a figure explaining the method to calculate the real size of a photographic subject concerning the present invention. It is a figure explaining the method to determine the scale of the distance axis which concerns on this invention. It is a figure explaining the method to determine the height and width of the subject position mark according to the present invention. It is a figure explaining the example of a display of a subject distance graph at the time of recognizing a person's face. It is a figure explaining the example which highlights the to-be-photographed object which exists within the depth of field of the to-be-photographed image which concerns on this invention. It is a figure explaining the other example which highlights the to-be-photographed object which exists within the depth of field of the to-be-photographed image which concerns on this invention. It is a figure explaining the example at the time of highlighting the subject position mark of the person concerning the present invention. It is a figure explaining the example of a display at the time of dividing and displaying the subject picture and subject distance graph concerning the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens system 2 Image pick-up element 3 Camera signal processing circuit 4 Zoom magnification calculation circuit 5 F value detection circuit 6 Focal length calculation circuit 7 Distance image sensor 8 Subject distance graph creation circuit 9 Image composition circuit 10 Display apparatus 11 Depth of field band 12 Object subject position mark 13 Human subject position mark 14 Focus position mark 15 Distance axis

Claims (8)

In an imaging device for photographing a subject,
Means for detecting subject distance information;
Means for extracting a subject according to a distance based on the distance information;
Means for calculating focus information based on the focal length and the aperture value of the aperture obtained from the position of the focusing lens;
The focus information is added to the subject position mark indicating the position of the subject created based on the extracted subject displayed on the graph with the subject image and the distance as an axis on the display screen. Display means for displaying a subject distance graph;
An imaging apparatus comprising:   The imaging apparatus according to claim 1, wherein the subject distance graph is combined with the subject image and displayed on the display screen.   The imaging apparatus according to claim 1, wherein the subject distance graph is displayed on one of the divided screens of the display screen, and the subject image is displayed on the other divided screen. .   4. The imaging apparatus according to claim 1, further comprising means for measuring the size of the extracted subject, wherein the subject position mark changes display according to the size of the subject. .   5. The imaging apparatus according to claim 1, wherein the focus information includes a focus position mark indicating the focus position and a depth-of-field band indicating the depth of field.   6. When a person is recognized as a subject, the subject position mark of the person is displayed and the subject position marks other than the person are not displayed, or the subject position mark corresponding to the person is highlighted. The imaging device according to any one of the above.   The distance axis of the subject distance graph is scaled so that the closest subject and the farthest subject can be accommodated, the distance range specified by the user centered on the focus position, or the depth of field can be accommodated. The imaging device according to claim 1, wherein the imaging device is determined.   The imaging apparatus according to claim 1, wherein a subject within a depth of field is highlighted in the subject image.