JP2001330769A - Image pickup device and its control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image pickup device capable of obtaining a high-quality monitor image from an image for focusing without complicating constitution, and its control method. SOLUTION: Luminous flux from an object is guided to an area sensor 106 from the mutually different pupil positions 101a and 101b of a photographing lens 101 through a field lens 103, a diaphragm 104 and a secondary image- formation lens 105 (a pair of lenses 105a and 105b), and a pair of picked-up image planes 106a and 106b having parallax that the pupil positions are different is obtained. A focal distance and a defocusing amount are measured by a focus detection part 109 from a pair of picked-up images related with a pair of picked-up image planes 106a and 106b, and the vignetting state of the picked-up image is detected by a vignetting detection part 112. The image having the smaller vignetting out of a pair of picked-up images is selected and switched by a display processing part 111, and outputted to a display part 113 so as to be displayed on a monitor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an imaging apparatus for detecting a focus from a captured image and displaying the captured image on a monitor, and a control method therefor.

[0002]

2. Description of the Related Art Conventionally, a technique for optically measuring a distance to an object existing in a plurality of directions has been known, for example, in Japanese Patent Publication No. 4-67.
No. 607. According to this technique, distance distribution information and defocus distribution information of an object existing in an object scene can be obtained, and it is possible to recognize an object arrangement state of the object scene from the distribution information. In this method, a known correlation operation is performed between parallax images based on a pair of images having parallax obtained by photographing with a stereo camera or the like using a CCD image pickup device, and the principle of triangulation. Thus, the distance to the object and the defocus for each calculation area can be measured. By performing these calculations in the same manner for each area of the captured image, distribution information of distance and defocus can be obtained.

[0003] Another conventional technique uses a focus detection device of a TTL (through-the-lens) camera, and uses a focus detection device of a TTL (through-the-lens) camera to perform relative displacement of a plurality of subject images caused by light beams coming from regions having different pupil positions of an imaging optical system. A so-called pupil division type automatic focus detection method for detecting a focus adjustment state of an imaging optical system from an amount is known. In this method, the focus is detected by an automatic focus detection device including a pair array of a lens array arranged near the primary image plane and a light receiving element array arranged immediately after the lens array. Alternatively, a field lens arranged on the primary image plane, two re-imaging lenses for re-imaging an image formed on the primary image plane on the secondary image plane, and two re-imaging lenses arranged on the secondary image plane The focus is detected by an automatic focus detection device including the image sensor array.

[0004] In an image pickup apparatus provided with the focus detection device of the phase difference detection method, it is determined whether or not vignetting of the distance measuring light beam is present based on, for example, the open F number information of the photographing lens, and whether or not the focus detection device is operable. Was determined. However, in the case of a general photographic taking lens, as shown by the fact that the pupil area called vignetting is reduced at an image plane position outside the optical axis, two exit windows (exit pupils) are non-paraxial. )have. Therefore, it is difficult to determine whether or not the distance measuring light beam is included in the photographing light beam only from the open F number information for the distance measuring visual field outside the optical axis of the photographing lens. Therefore, it is necessary to consider the exit window in the focus detection device, especially in the interchangeable photographing lens.

When an image picked up by an area sensor or the like is electronically displayed on a monitor or the like, the image for distance measurement is output and displayed, that is, the image for distance measurement is also used as an image for monitor display. It is possible to do.

[0006]

However, when an image for distance measurement is used for displaying a monitor image, it may be difficult to stably display the entire field of view with high quality due to vignetting. On the other hand, for example, if an area sensor for distance measurement and an area sensor for a finder of a photographing visual field image are separately provided, and an image obtained from the area sensor for the photographing visual field image is displayed on a monitor, it is affected by vignetting. You don't have to. However, if the area sensor is separately provided, there is a problem that the configuration becomes complicated, which leads to an increase in cost.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide an imaging system capable of obtaining a high-quality monitor image from a ranging image without complicating the configuration. An apparatus and a control method thereof are provided.

[0008]

According to another aspect of the present invention, there is provided an imaging apparatus for receiving an image of a subject through different optical paths and electronically obtaining at least one pair of captured images. Means, and an imaging apparatus comprising: focus detection means for detecting focus information from the pair of captured images;
Vignetting detecting means for detecting vignetting of the pair of captured images, respectively, and switching output means for selectively switching and outputting any of the pair of captured images based on vignetting detected by the vignetting detecting means. And image display means for displaying the captured image output by the switching output means.

In order to achieve the same object, according to a second aspect of the present invention, in the imaging apparatus according to the first aspect, the switching output means is configured to detect less vignetting in the pair of captured images. Is output.

In order to achieve the same object, according to a third aspect of the present invention, in the configuration of the first or second aspect, the different optical paths are defined by predetermined pupil positions obtained by pupil division. It is characterized by the following.

In order to achieve the same object, according to a fourth aspect of the present invention, in the image pickup apparatus according to any one of the first to third aspects, the image pickup means comprises a color image filter using a color filter. And the selective switching of the pair of captured images by the switching output unit can be performed based on a color filter cycle of the color filter.

In order to achieve the same object, according to a fifth aspect of the present invention, in the image pickup apparatus according to the fourth aspect, the selective switching of the pair of picked-up images by the switching output means is performed by the color image forming apparatus. It can be performed at a cycle that is an integral multiple of the color filter cycle of the filter.

In order to achieve the same object, an image pickup apparatus according to claim 6 of the present invention is characterized in that, in the constitution described in claim 4 or 5, the color filter includes at least three primary colors of light.

In order to achieve the same object, according to a seventh aspect of the present invention, in the image pickup apparatus according to any one of the fourth to sixth aspects, the color filter cycle of the color filter is one cycle thereof. Includes at least the entire visible light range.

According to another aspect of the present invention, there is provided an imaging apparatus according to any one of the first to seventh aspects, wherein the microlens corresponds to the pair of captured images. An array is provided.

According to another aspect of the present invention, there is provided an image pickup apparatus and a control method thereof, wherein the image pickup step receives an object image via different optical paths and electronically obtains at least one pair of image pickup images. A focus detection step of detecting focus information from the pair of captured images, wherein the vignetting detection step of detecting the vignetting of each of the pair of captured images; A switching output step of selectively switching and outputting one of the pair of captured images based on the vignetting, and an image display step of displaying the captured image output by the switching output step. Features.

In order to achieve the same object, according to a tenth aspect of the present invention, in the configuration of the ninth aspect, the switching output step is such that the switching output step is performed by detecting the detected one of the pair of captured images. It is characterized by outputting the one with less vignetting.

According to another aspect of the present invention, there is provided an image pickup apparatus and a control method therefor according to the present invention, wherein the different optical paths are divided into predetermined pupil positions. Is characterized by:

In order to achieve the same object, an image pickup apparatus and a control method thereof according to a twelfth aspect of the present invention are provided.
In the configuration according to any one of the first to third aspects, the imaging step can capture a color image using a color filter, and the selective switching of the pair of captured images by the switching output step includes the color image processing. It can be performed based on the color filter period of the filter.

In order to achieve the same object, according to a thirteenth aspect of the present invention, there is provided an imaging apparatus and a control method therefor according to the twelfth aspect, wherein the pair of captured images is selectively switched by the switching output step. May be performed at a cycle that is an integral multiple of the color filter cycle of the color filter.

In order to achieve the same object, according to a fourteenth aspect of the present invention, in the image pickup apparatus and the control method therefor, the color filter includes at least three primary colors of light. And

To achieve the same object, an image pickup apparatus and a control method thereof according to claim 15 of the present invention are described.
15. The configuration according to any one of the fourteenth aspects, wherein the color filter cycle of the color filter includes at least the entire range of visible light in one cycle.

In order to achieve the same object, an image pickup apparatus and a control method therefor according to claim 16 of the present invention are provided.
6. The configuration according to any one of items 5, wherein the pair of captured images is obtained via a corresponding microlens array.

[0024]

Embodiments of the present invention will be described below with reference to the drawings.

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

In FIG. 1, reference numeral 101 denotes a photographing lens;
2 is a quick return mirror, 103 is a field lens, 104 is an aperture, 105 is a secondary imaging lens, 106 is an area sensor (imaging means), 116 is a shutter curtain, 11
7 is a film surface. Further, an imaging processing unit 107 is connected to the area sensor 106. Imaging processing unit 107,
Focus detection unit 109 (focus detection means), display processing unit 111
The (switching output unit) and the vignetting detecting unit 112 (vignetting detecting unit) are connected in series. An image output unit 108 is further connected to the imaging processing unit 107, and a focus detection unit 109
Is connected to a focus output unit 110. Display processing unit 1
A display unit 113 (image display means) is connected to 11, and the image displayed on the display unit 113 is recognized as a visible image by the photographer 115 via the eyepiece 114.

The subject image passes through the taking lens 101, is reflected by the quick return mirror 102, and forms a field lens 103, an aperture 104, and a secondary imaging lens 105.
Through the area sensor 106. On the other hand, the quick return mirror 102 and the shutter curtain 116 are configured to be retractable.
Exposure recording becomes possible at 7.

FIG. 2 is a partial external perspective view showing the detailed configuration of the optical system. The quick return mirror 102
Has been omitted.

A light beam from a subject is passed from a different pupil position 101a, 101b (predetermined pupil position) of the photographing lens 101 via a field lens 103, an aperture 104, and a secondary imaging lens 105 (a pair of 105a, 105b). It is led to the area sensor 106. Each light beam is re-imaged at an imaging magnification determined by the field lens 103 and the secondary imaging lens 105, and imaging screens 106a and 106b (a pair of captured images) are obtained. The area sensor 106 is disposed at a position optically equivalent to the film surface 117 with respect to the taking lens 101, and the imaging screens 106a and 106b have a part of the screen exposed on the film surface 117 or a field of view equal thereto. are doing. With this configuration, a pair of imaging screens 106a and 106b having parallax in which the pupil position of the imaging lens 101 is different can be obtained.

A pair of imaging screens 106 having this parallax
The pair of captured images related to a and b are output to the imaging processing unit 107 as electronic image data, stored, and, if necessary, from the imaging processing unit 107 to the image output unit 10.
8, supplied to the focus detection unit 109, the display processing unit 111, and the vignetting detection unit 112. The image output unit 108 outputs the supplied captured image to an external device (not shown) or stores the captured image in a storage medium.

The focus detection unit 109 performs a well-known correlation operation between the signals in the corresponding blocks based on the supplied pair of captured images, and calculates the distance to the object in the previous block and the defocus. The amount can be measured. If necessary, a distance map or a defocus map can be obtained by performing this measurement on all blocks, and the result is output to the focus output unit 110. The focus output unit 110 can realize automatic focus adjustment by driving the photographing lens 101 with a drive unit (not shown) based on the detection result of the focus detection unit 109 and adjusting the focus position.

The vignetting detection unit 112 includes a pair of imaging screens 1
The detected vignetting state of each of the captured images 06a and 106b is detected by a known method, and the detected information is displayed on the display processing unit 11.
Output to 1. The vignetting detection information is also supplied to the focus detection unit 109 via the display processing unit 111, and the focus detection unit 10
9 is provided for the correction information of the focus detection calculation by 9.

The display processing unit 111 creates optimum display data from a pair of pupil-divided picked-up images based on the vignetting detection information, and outputs it to the display unit 113. That is, the display processing unit 111 selects and switches the image having less vignetting from the pair of captured images and outputs the selected image to the display unit 113. The display unit 113 displays the supplied captured image, and provides a monitor display of a captured visual field image to the photographer 115 via the eyepiece 114. As a result, a high-quality image is output to the monitor.

On the other hand, when the photographer presses a shutter button (not shown), a series of predetermined photographing processing operations are performed. That is, the quick return mirror 102 and the shutter curtain 11
6, the subject image is exposed on the film surface 117 and photographed.

Next, the occurrence of vignetting will be described.

FIG. 3 is an external perspective view showing the relationship between the photographic lens and the area sensor light flux in a developed manner.

In the figure, reference numeral 301 denotes an area sensor shooting screen, 301a denotes an optical axis position of a shooting lens, and 301b denotes
This is a peripheral position that deviates from the optical axis position 301a in the horizontal direction of the photographing screen 301. 302 is the rear frame of the lens, 303 is the aperture of the lens, 304 is the front frame of the lens, 305a and 30
5b are an optical axis position 301a and a peripheral position 301b, respectively.
7 shows an image back-projected through the aperture of FIG.

The optical axis position 301a at the center of the photographing screen 301
Is not affected by vignetting,
The back projection image 305b from the peripheral position 301b is
4 and the vignetting of the rear frame 302. Thus, it can be seen that there is a difference in the effect of vignetting depending on the position on the shooting screen.

By the way, the photographing light flux varies depending on the aperture value, the interchangeable lens, the zoom position, the position of the distance ring, and also changes with respect to the position in the photographing screen.

FIG. 4 is a diagram showing the relationship between the horizontal distance from the optical axis in the area sensor and the sensor output.

When the pupil split images a and b are compared, a difference occurs in the sensor output level between the pupil split images a and b depending on the distance from the optical axis. For example, the output level of the pupil division image a is
As shown in FIG. 7A, there are cases where the distance increases from the optical axis to the left, and conversely, as shown in FIG. As described above, depending on the position from the optical axis, the output level may be reversed between the images a and b.

Such phenomena are not limited to those described above, but variously change depending on various conditions such as the above-mentioned aperture value and interchangeable lens. Therefore, the pupil division image a or the pupil division image b cannot be uniformly determined as the display image to be selected. In the present embodiment, it is possible to select and display a more appropriate image with less vignetting depending on the image position.

Although the area sensor 106 has been described for black and white, it may be configured for color. In that case, a color filter (not shown) is used, but the switching of the output display image by the display processing unit 111 is performed in the color filter cycle of the color filter. For example, when a color filter having a stripe configuration of red (R), green (G), and blue (B) is used, one cycle of R, G, and B is switched every cycle. That is, the switching from the screen a to the screen b is not performed in the middle of one cycle, and the vignetting comparison and determination is performed every one cycle, and the image may be switched to the image with less vignetting. The switching may be performed at a cycle that is an integral multiple of one cycle. Thus, an appropriate monitor display can be performed on a color image.

The color filter may use four colors of yellow, cyan, magenta, and green. However, for proper monitor display, the color filter includes at least three primary colors of light, and one cycle of the color filter. Desirably includes at least the entire visible light range.

According to the present embodiment, the pupil division image or the parallax image for focus detection is also used for monitor display, so that the configuration is not complicated and the cost does not increase. Moreover, at this time, since the image having less vignetting is selectively switched and displayed, deterioration of the quality of the displayed image can be minimized. Therefore, a high-quality monitor image can be obtained from the ranging image without complicating the configuration.

(Second Embodiment) FIG. 5 is a block diagram showing a configuration of an imaging apparatus according to a second embodiment of the present invention. The same components as those in the first embodiment (FIG. 1) are denoted by the same reference numerals, and description thereof will be omitted. In the present embodiment, the pupil division method is different from that of the first embodiment.

In the figure, reference numeral 501 denotes a microlens array, which is arranged one for each two pixels of the area sensor 502. That is, one microlens array 501 is arranged for one pair of pixels.

FIG. 6 is a side view showing the relationship between the micro lens array 501 and the area sensor 502.

The microlens arrays 501 are arranged one by one corresponding to the two pixels a and b of the area sensor 502. Light beams having different pupil positions of the photographing lens 101 are incident on the pixels a and b. Therefore, an image A composed of only the pixels corresponding to the pixel a of the area sensor 502 and an image B composed of only the pixels corresponding to the pixel b have different pupil positions. The display processing unit 111 selects, switches, and outputs to the display unit 113 based on the vignetting detection information by the vignetting detection unit 112 for each of the image A and the image B, so that a high-quality and faithful image can be easily displayed on a monitor. Is done.

According to this embodiment, not only the same effects as in the first embodiment can be obtained, but also a higher-quality and faithful image can be displayed on a monitor.

[0051]

As described above, according to the present invention,
A pair of captured images for focus detection is also used for monitor display, and one of them is displayed based on the vignetting of each image. Therefore, a high-quality monitor image can be obtained from the ranging image without complicating the configuration. Can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an imaging device according to a first embodiment of the present invention.

FIG. 2 is a partial external perspective view showing a detailed configuration of an optical system according to the embodiment.

FIG. 3 is an external perspective view showing a developed relationship between a photographic lens and an area sensor light beam in the same embodiment.

FIG. 4 is a diagram showing a relationship between a horizontal distance from an optical axis in the area sensor and a sensor output in the embodiment.

FIG. 5 is a block diagram illustrating a configuration of an imaging device according to a second embodiment of the present invention.

FIG. 6 is a side view showing a relationship between a microlens array and an area sensor in the same embodiment.

[Explanation of symbols]

 101 imaging lens 101a, 101b pupil position (predetermined pupil position) 103 field lens 104 aperture 105 secondary imaging lens 106 area sensor (imaging means) 106a, 106b imaging screen (a pair of captured images) 107 imaging processing unit 108 image Output unit 109 Focus detection unit (focus detection unit) 110 Focus output unit 111 Display processing unit (switching output unit) 112 Vignetting detection unit (vignetting detection unit) 113 Display unit (image display unit) 501 Micro lens array 502 Area sensor

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H04N 5/225 H04N 5/232 H 5C022 9/04 Z 5C065 5/232 G02B 7/11 C 9/04 G03B 3/00 A F term (reference) 2H011 AA01 BA21 DA05 2H018 BE00 2H051 BA04 BA06 CB22 GA03 GA09 GA12 GA17 GB15 2H054 CD03 2H083 AA02 AA26 AA32 AA51 5C022 AA13 AB28 AC01 AC42 AC54 AC55 AC69 5C065 AA03 CB11

Claims (16)

[Claims] An imaging unit that receives an object image via different optical paths and electronically obtains at least one pair of captured images; and a focus detection unit that detects focus information from the pair of captured images. In the imaging apparatus, vignetting detection means for respectively detecting vignetting of the pair of captured images, and selectively switching and outputting any of the pair of captured images based on vignetting detected by the vignetting detecting means. An image pickup apparatus comprising: a switching output unit that performs switching; and an image display unit that displays an image of a captured image output by the switching output unit. 2. The imaging apparatus according to claim 1, wherein the switching output unit outputs the one of the pair of captured images having less detected vignetting. 3. The method according to claim 1, wherein the different optical paths are defined by predetermined pupil positions obtained by pupil division.
Or the imaging device according to 2. 4. The imaging unit is capable of capturing a color image using a color filter, and the switching output unit selectively switches the pair of captured images based on a color filter cycle of the color filter. The imaging device according to any one of claims 1 to 3, wherein the imaging device can be executed. 5. The imaging apparatus according to claim 4, wherein the switching between the pair of captured images by the switching output unit can be performed in a cycle that is an integral multiple of a color filter cycle of the color filter. . 6. The color filter according to claim 3, wherein at least three
The imaging device according to claim 4, wherein the imaging device includes a primary color. 7. The imaging device according to claim 4, wherein one cycle of the color filter of the color filter includes at least the entire visible light range. 8. The imaging device according to claim 1, wherein a microlens array is arranged corresponding to the pair of captured images. 9. An imaging method comprising: an imaging step of receiving a subject image via different optical paths to electronically obtain at least one pair of captured images; and a focus detection step of detecting focus information from the pair of captured images. In the control method of the apparatus, a vignetting detection step of detecting vignetting of each of the pair of captured images, and selectively switching any one of the pair of captured images based on the vignetting detected by the vignetting detecting step And a switching output step of outputting the captured image, and an image displaying step of displaying an image of the captured image output in the switching output step. 10. The control method according to claim 9, wherein the switching output step outputs the one of the pair of captured images having less detected vignetting. 11. The control method according to claim 9, wherein the different optical paths are defined by predetermined pupil positions obtained by pupil division. 12. The image capturing step is capable of capturing a color image using a color filter, and the selective switching of the pair of captured images in the switching output step is based on a color filter cycle of the color filter. The method for controlling an imaging device according to claim 9, wherein the control method can be performed. 13. The imaging apparatus according to claim 12, wherein the selective switching of the pair of captured images in the switching output step can be performed at a cycle that is an integral multiple of a color filter cycle of the color filter. Control method. 14. The method according to claim 12, wherein the color filter includes at least three primary colors of light. 15. The control method according to claim 12, wherein one cycle of the color filter of the color filter includes at least the entire visible light range. 16. The control method according to claim 9, wherein the pair of captured images are obtained through a corresponding microlens array.