JPH1169205A - Camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the operating convenience of the camera by allowing the user to confirm a layout of film photographing by a device other than the finder. SOLUTION: An electric image-pickup element with a few pixels is provide for a film-photographing camera and proper low gradation processing (2-4 gradation processing) is applied to an object which is image picked up by the image- pickup element, and the processed image is displayed on a low gradation liquid crystal display panel 12. Moreover, the low gradation liquid crystal display panel 12 is to be used in common with a low gradation liquid crystal display panel, on which information relating to photographing provided to a conventional camera is displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film photographing camera in which an observer looks at a finder and confirms a composition to take a picture. More particularly, the present invention relates to a camera capable of confirming a photographing composition from outside the camera. .

[0002]

2. Description of the Related Art In using a film photographing camera, a user checks a photographing composition by looking through a viewfinder, and then performs a photographing operation (release).

[0003]

However, various inconveniences arise if only the finder is provided as the composition confirmation means. For example, if the spectacle wearer presses the spectacles against the finder eyepiece and makes the spectator look through the finder, inconveniences such as a shift of the spectacles occur. Further, in order for the spectacle wearer to be able to look through the viewfinder with the naked eye, it is necessary to take measures such as installing a diopter correction lens in the viewfinder eyepiece. Furthermore, during self-timer shooting or the like, the user may be in an unsuitable posture to look through the viewfinder depending on the installation location of the camera.

[0004] In addition, when photographing a person, when the user looks into the finder and looks at the person, the person who is the subject tends to be unconsciously holding the photographed person, and tends to be photographed with an unnatural expression.

[0005] In this regard, in a digital camera which has been frequently used recently, the photographing composition can be confirmed by looking through a viewfinder, and the photographing composition can be confirmed by looking at a liquid crystal viewfinder (hereinafter referred to as EVF) provided outside the camera. You can also. In other words, the digital camera is provided with two means, a finder and an EVF, as means for checking the composition, and the user can use them properly according to the situation.

However, in a camera for film photographing, an EVF that requires an image pickup device and a multi-tone liquid crystal device is expensive, and the EVF is not necessary.
Those with F are considered to be difficult to put into practical use.

Accordingly, an object of the present invention is to provide a camera with a relatively simple and low-cost configuration that allows a user to confirm a shooting composition from outside the camera.

[0008]

In order to solve the above-mentioned problems, in the present invention, a film photographing camera is provided with an electric image pickup device having a small number of pixels, and an image pickup device suitable for a subject image picked up by the image pickup device. After the low gradation processing (2-4 gradation processing) is performed, this processed image is displayed on a low gradation liquid crystal panel, and the low gradation liquid crystal panel is provided in a conventional camera. The LCD is also used as a low gradation liquid crystal panel for displaying information related to shooting.

With such a configuration, an inexpensive and easy-to-use camera is realized simply by adding a low-cost image sensor having a small number of pixels and a low-gradation liquid crystal panel to the conventional camera.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIGS. 1 to 3 show a configuration of a single-lens reflex camera according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a photographing lens that forms a subject image.
Reference numeral 3 denotes a shutter (focal plane shutter or the like) which controls the amount of exposure light to the film 4. Reference numeral 5 denotes a focus plate, which is disposed conjugate with the film 4 via the quick return mirror 2 with respect to the light beam from the photographing lens 1.

Reference numeral 2 denotes a quick return mirror for switching the optical path from the taking lens 1. This quick return mirror retracts outside the exposure optical path during film exposure,
The luminous flux from the taking lens 1 is guided through the shutter 3 onto the film 4 to form a subject image thereon. On the other hand, at the time of non-exposure, the light beam is obliquely provided in the exposure light path (the position indicated by the solid line in the drawing), and guides the light beam from the photographing lens 1 onto the surface of the focusing plate 5 to form a subject image.

Reference numeral 6 denotes a pentaprism, which is an eyepiece lens 10 which will be described later, using an object image on the focus plate 5 as an erect image.
The light beam from the focus plate 5 is reflected and deflected so that the light beam can be observed through the light source.

Reference numeral 7 denotes a half mirror, which shifts the subject image on the focus plate 5 to about 4: 6 on the area sensor side and the eyepiece side.
Divide by the ratio of Reference numeral 9 denotes an area sensor (imaging element) having 256 luminance gradations of 7000 pixels, and 8 denotes an imaging lens for forming an object image on the focus plate 5 on the imaging surface of the area sensor 9. Reference numeral 10 denotes an eyepiece, which guides a light beam from the pentaprism 6 to an observer's eyeball.

Reference numeral 11 denotes a one-chip microcomputer, which controls the entire camera and processes image information picked up by the area sensor 9.

Reference numeral 12 denotes a two-gradation dot matrix liquid crystal panel provided on the back of the camera body. The liquid crystal panel includes information relating to the shutter speed, aperture value, remaining amount of the power battery of the camera, the number of film frames, the photographing mode and other photographing shown in FIG. 2B, and the area sensor 9 shown in FIG. And a framing image that has been subjected to a two-gradation process described later is selectively displayed. 18
Is a mode dial for setting a shooting mode or the like in accordance with the operation of the user, and 19 is a release button. next,
The binarization processing of the subject image and the display of the framing image in the microcomputer 11 will be described with reference to the flowcharts of FIGS. The portion indicated by X1 in FIG. 4 is connected to the portion indicated by X1 in FIG.

The microcomputer 11 detects that the power of the camera is turned on (# 100), and further detects the setting of the EVF mode by the photographer operating the mode dial 18 (# 10).
1) The standard data accumulation time and gain value of the area sensor 9 stored in the memory of the microcomputer 11 in advance are set (# 102), and the apparatus enters a standby state for driving the area sensor 9.

Next, when the photographer operates the release switch 19 for the first stroke while fixing the viewfinder display area in a desired composition (# 103), the area sensor 9 is set in accordance with the previously set accumulation time and gain value. Drive the
The image information captured by the area sensor 9 is stored in the buffer (# 104). Subsequently, an average value (average photometric value) of the data stored in the buffer is calculated (# 10).
5). Then, it is determined whether or not the calculated average photometric value exceeds a value in a predetermined range set in advance (# 106).
If it exceeds, it is determined that the accumulation time and the gain value of the area sensor 9 are inappropriate for the subject brightness, and the accumulation time and the gain value are reset according to the average photometric value (# 102). Then, in response to the first stroke operation of the release switch 19 again, the operations of # 102 to # 106 are repeated until the average photometric value falls within the predetermined range. When the average photometric value falls within the predetermined range, this operation is performed. finish. Next, the area sensor 9 is controlled to accumulate data of the subject image in the RAM in the microcomputer 11 (# 107).
The image data is subjected to the two-gradation processing in the following steps.

First, with respect to image data (gray scale image) of 256 gradations and 7000 pixels captured by the area sensor 9 into the RAM, a differential value is calculated by calculation of three neighborhoods of each pixel using a Robert's differential operator. Is performed (# 108). This derivative operator is 3
In the nearby second derivative processing, it is possible to extract a uniform differential value in the vertical, horizontal, and oblique directions. As shown in FIG.
Calculation of the differential value for the pixel a is performed by the equation shown in FIG.

Next, a secondary differential value necessary and sufficient to reproduce the contour of the subject is extracted from the secondary differential values by threshold processing (# 109). In the present embodiment, a discriminant analysis method is used for the threshold processing. That is, the average value μ _T of the differential value of the entire dynamic range, the probability ω (k) up to the threshold value (differential value) k, and the threshold value (differential value) k
The class separation η (k), which is the ratio of the inter-class variance σ _B ² (k) composed of the average value μ (k) up to and the variance σ _T ² of the entire dynamic range. The threshold value is determined based on the maximum value of Expression (2).

[0020]

(Equation 1)

This method of finding the maximum value of equation (2) is highly versatile in that it can uniquely determine a threshold value using only information obtained from the dynamic range, and is suitable for the purpose of the present invention. I have. Therefore, a threshold value is determined for the dynamic range of the above-described differential value using this method, and a differential value necessary for expressing a subject is extracted.
FIG. 7 is a graph showing the dynamic range and the degree of separation between classes.

Next, a process of removing an isolated differential value, that is, noise, from the differential value extracted by the threshold value process is performed (# 110). For this purpose, a median filter that deletes only isolated points without cutting edges is applied to all pixels.

Subsequently, edges (line segments) are smoothed in order to clearly show the outline of the subject image. (# 111). As shown in FIGS. 8 (a) and 8 (b), this is a 9-neighbor process for each pixel, and only a value having a connection of three adjacent pixels in three directions of each pixel is left, and a differential without connection is left. Reduce for values. As a result, a differential image as shown in FIG.

Finally, band processing on the dynamic range of the original subject image (# 106) having the luminance gradation is performed (# 112). This is shown in FIG.
The pixel of the differential image corresponding to the pixel A having the upper limit a% luminance value and the pixel B having the lower limit b% luminance value is painted black or white. As a result, it is possible to give a sense of realism to an image including only the differential value.

A framing image composed of two gradations can be generated from a subject image with 256 luminance gradations by a series of binary gradation processing algorithms as described above. Then, as shown in FIG. 10, the microcomputer 11 displays the framing image G on the liquid crystal panel 12 which has been displaying the information about the photographing as shown in FIG. 2B (# 113). Thus, the photographer can check the photographing composition without looking through the viewfinder.

According to the present embodiment, the area sensor 9 is added to the camera that has been used conventionally, and the microcomputer 11 is added with software for processing the image data fetched by the area sensor 9 into two gradations. An easy-to-use camera having a simple and inexpensive EVF function can be realized.

In the present embodiment, an example has been described in which the image data fetched by the area sensor 9 is subjected to two-gradation processing. May go. Further, instead of the two-gradation processing, a three- or four-gradation processing may be performed.

Further, in the present embodiment, the case where the panel for displaying the information regarding the photographing and the panel for displaying the framing image are used has been described, but these may be provided separately.

Further, although the present embodiment has been described with respect to a single-lens reflex camera, the present invention can be applied to cameras other than a single-lens reflex camera.

[0030]

As described above, according to the present invention,
Since the subject image picked up by the image pickup device is subjected to an appropriate gradation reduction process (2-4 gradation processing) and then this processed image is displayed on a low gradation liquid crystal panel, the conventional image processing method is used. By simply adding a low-cost image sensor with low pixel count and a low-grayscale LCD panel to the camera (the low-grayscale LCD panel can also be used as a low-grayscale LCD panel that displays information related to shooting that was provided in conventional cameras) In this case, it is possible to realize an inexpensive and easy-to-use camera that can easily confirm the shooting composition from outside the camera without looking through the viewfinder.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a single-lens reflex camera according to a first embodiment of the present invention.

FIG. 2 is a rear view showing a state in which shooting information is displayed in the camera and a state in which a framing image is displayed.

FIG. 3 is an external perspective view of the camera.

FIG. 4 is a flowchart of area sensor control in the camera.

FIG. 5 is a flowchart showing a binary tone processing algorithm in the camera.

FIG. 6 is an explanatory diagram of a Robert differential operator in the two-gradation processing.

FIG. 7 is a diagram illustrating a relationship between a frequency with respect to a differential value, an inter-class separation degree, and a threshold value in the two-gradation processing.

FIG. 8 is an explanatory diagram of edge smoothing in the two-gradation processing.

FIG. 9 is an explanatory diagram of band processing of a grayscale image in the two-tone processing.

FIG. 10 is an external view of the camera when displaying a framing image.

[Explanation of symbols]

 Reference Signs List 1 shooting lens 2 quick return mirror 3 shutter 4 film 5 focus plate 6 pentaprism 7 half mirror 8 imaging lens 9 area sensor 10 finder eyepiece 11 1 chip microcomputer 12 liquid crystal panel

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // G06T 1/00 G06F 15/64 320A

Claims (5)

[Claims] 1. A camera for photographing a subject image on a film, comprising: an imaging unit for electrically capturing the subject image; a processing unit for performing a gradation reduction process on the subject image captured by the imaging unit; And a display unit for displaying a processed image by the camera. 2. The camera according to claim 1, wherein the low-gradation processing is any one of two-level processing to four-level processing. 3. The gradation reduction processing includes any one of differentiation processing, threshold processing, noise processing, edge smoothing processing, and dynamic range band processing of a grayscale image captured by the imaging unit. The camera according to claim 1, wherein the processing is processing. 4. The camera according to claim 1, wherein said display means also serves as a means for displaying information relating to film shooting. 5. The camera according to claim 1, wherein said display means is a low gradation liquid crystal panel.