JP3164692B2 - Electronic still camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic still camera, and more particularly to an electronic still camera capable of automatically photographing a good face when a person's face is photographed up.

[0002]

2. Description of the Related Art In general, a subject to be photographed by a camera is often a person, and particularly in the case of family use, a portrait of a family is often photographed. Therefore, how to take a good picture of a person is an important function required of a camera.

[0003] In portrait photography, a general technique is known in which the depth of field is controlled to be shallow to make only a person stand out clearly. This technique is effective especially in a condition where the depth of field is shallow, such as shooting a person up.

FIG. 3 is a flowchart showing the judgment and operation of the photographer when such a photographing technique is manually performed. The photographer first determines that the subject is a person, and when shooting with a technique that shoots with a shallow depth of field,
The camera mode is set to a mode in which the aperture can be controlled (for example, an aperture priority AE mode).

Next, the photographer measures the distance to the subject. In the case of a single-lens reflex camera or a distance meter-linked camera, focusing is first performed, and the distance is measured using a distance scale displayed on the lens. Next, the depth of field is checked, and the camera is set so that the entire face of the subject is focused and objects at other distances are blurred.

In order to confirm the depth of field, generally, a scale of the depth of field attached to the lens is read. In the case of a single-lens reflex camera, the degree of blurring can be confirmed in advance by performing an aperture-down operation.

In the case of strict control, the depth of field is confirmed based on the following formula.

[0008]

D1 = (δFx2) / (f2 + δFx)

[0009]

D2 = (δFx2) / (f2−δFx) where, d1 front depth of field d2 rear depth of field f focal length of imaging lens F F-number of imaging lens x up to focused position Distance δ Allowable diameter of blur on the image plane The operation of confirming the depth of field is very troublesome, and in particular, confirmation based on a calculation formula is impossible in actual photographing.

Therefore, in some single-lens reflex cameras, when the distance between the front and the back of the range to be focused is input, an operation based on this formula is performed inside the camera, and the aperture and the like are controlled to control the designated range. Some cameras have a function to focus only on the subject and shoot. After confirming the depth of field, the aperture and the focal length are set so as to obtain a desired photographing effect, and photographing is performed.

[0011] Even in the method in which the camera calculates the depth of field, which is relatively easy to operate, the range to be focused must be input, which is not a practical method for portrait photography or the like.

It is also inconvenient for a general user to set the shooting mode each time the subject is determined to be a person.

[0013]

2. Description of the Related Art To shoot with this conventional technique, it is possible to use a camera whose aperture value can be freely determined. However, even if the camera has the function, a general photographer can use the technique. Actually, such photographing is not actually performed due to lack of knowledge and experience to be used and complicated and troublesome judgment and operation.

Therefore, a camera configuration is proposed that allows even a beginner to easily perform such a photographing technique.

[0015]

In order to solve the above-mentioned problems, an electronic still camera for recording an image taken by an image pickup means on a recording medium, wherein a subject is a person based on image information output from an image pickup device. A person judging means for judging that the distance to the subject, and a distance detecting means for detecting a distance to the subject, and when the person judging means determines that the subject is a person, the distance to the subject obtained by the distance detecting means Control means for adjusting the focal length, the focal position, and the aperture of the taking lens based on the information on the distance, and controlling the entire face of the person to be substantially in the depth of field. Suggest.

By controlling the depth of field to about 10 cm before and after the focal position, it is possible to cope with the conditions of many human subjects.

[0017]

According to the present invention, good portrait photography can be performed automatically, and this is particularly effective in close-up photography.

[0018]

An embodiment according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of an embodiment of the present invention. In the figure, an image of a subject 11 is formed on an image sensor 13 by an image pickup optical system 12 and is converted into an electric signal. After the electric signal is amplified by the preamplifier, it is converted into a digital signal by the A / D converter 14. The digital signal is converted into a predetermined digital video signal by the signal processing circuit 15. The digital video signal is temporarily recorded in the frame memory 16 and then transferred to and recorded on the recording medium 17 as necessary. Frame memory 16
The digital video signal recorded in the camera is displayed on the electronic viewfinder 111 through the driver 110, and the photographer performs photographing while checking the displayed image. The CPU 19 controls the entire camera, and the CPU 19 instructs the memory controller 18 to read a digital video signal,
Write and transfer control.

The output from the signal processing circuit 15 is also input to the person detection circuit 112. Person detection circuit 112
Determines whether a person is included in the captured image. As a method of detection, besides judging from the shape of the subject, a method of detecting and judging a skin color component peculiar to a person by a method as disclosed in JP-A-52-22937 may be used. When the person detection circuit 112 determines that the subject is a person, the CPU 19 determines the information and enters the portrait shooting mode.

Here, in the case of portrait photography, the focus position is generally set to the eye in front of the subject. When a large-aperture, long-focus lens is used in an open state, the depth of field is extremely shallow, so that it is possible to take a picture in which only the front eye is focused and other parts are blurred. However, photographing with such an extremely shallow depth of field is rather unsuccessful unless the photographer has a considerable photographing technique (composition setting ability or the like).

Therefore, it is generally desirable to take a picture in which both eyes, that is, the entire face, are in focus. Since the left and right eyes of the person are separated by only about 10 cm, the distance will not be any longer even when photographed from any angle. Therefore, if the depth of field is set to be about this level, both eyes will be in focus regardless of which eye is focused.

In the camera according to the present invention, when the photographing mode is switched to the portrait photographing mode, the character generated by the character generator 113 is displayed in the electronic viewfinder 111, and the photographer can focus on the subject's eyes. Instruct them to match.

FIG. 2 shows the electronic viewfinder 111.
It is an explanatory view showing a display state inside. Reference numeral 31 denotes a focus frame which can focus on an object in the frame. Reference numeral 32 denotes a display superimposed on the image of the subject.
And focus on the eye of the subject.

At this time, the CPU 19 controls the person detection circuit 112
By referring to the output of (1), whether or not the subject in the focus frame is a person is monitored, and when it is determined that the subject is not a person, a warning display is performed or a shooting mode is forcibly switched to a normal mode. In the case of the portrait photographing mode, the CPU 19 calculates the depth of field at each aperture value from the distance information to the subject 11 and the focal length of the imaging lens according to Expressions 1 and 2.

If the depth of field in the state where the aperture is opened or opened to the limit of dimming is equal to or greater than a predetermined depth of field (for example, 10 cm), shooting is performed with the aperture value. As a result, it is possible to photograph an image in which the front and rear of the subject are as blurred as possible and which is preferable as a portrait.

When the depth of field in a state where the aperture is opened or opened to the limit of dimming is equal to or less than a predetermined depth of field, shooting is performed by narrowing the aperture to increase the depth of field. Do. At this time, if the appropriate shutter speed is lower than the camera shake limit, a warning is displayed in the viewfinder.

If the set depth of field is not reached even when the aperture is set to the minimum aperture, this fact is displayed in the viewfinder. However, in the case of an electronic still camera, a special close-up There aren't many such situations except for the example.

[0028]

According to the present invention, when taking a picture of a person, especially a close-up picture, it is possible to take a good picture taking advantage of the blur effect. In addition, since special mode switching operation is not required when performing such shooting,
The operation is simple and very convenient.

[0029]

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a display state in an electronic viewfinder.

FIG. 3 is a flowchart showing a conventional manual determination and operation performed by a photographer.

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 subject 12 imaging optical system 13 imaging element 14 A / D converter 15 signal processing circuit 16 frame memory 17 recording medium 18 memory controller 19 CPU 31 focus frame 32 character display 110 driver 111 electronic viewfinder 112 person detection circuit 113 character generator

Claims (1)

(57) [Claims] An electronic still camera for recording an image captured by an image capturing means on a recording medium, comprising: person determining means for determining that a subject is a person based on image information output from an image sensor; A distance detecting means for detecting a distance, and when the person determining means determines that the subject is a person, the focal length and the focal position of the photographing lens based on information on the distance to the subject obtained by the distance detecting means. And a control means for adjusting the aperture and controlling the entire face of the person so as to be substantially in the depth of field.