JPH01225927A - Metering device - Google Patents

Abstract

PURPOSE:To ensure the calculation of an appropriate exposure value by scanning data on the brightness of a photographic image plane in both lateral and longitudinal directions, recognizing the pattern of an object, extracting data on brightness from the data on brightness recorded in a storing means, and then operating the exposure value. CONSTITUTION:When an object is trapped on the photographic image plane, the storing means 30 records the output of the brightness of each area of the photographic image plane, metered by a photodetector 15, and a binarizing means 26 binarizes it. Then the binarized image data is scanned in both longitudinal and lateral directions, so that the position of the object and its size are detected. By comparing its position and size with the image pattern, which has been previously stored, the image of the object is recognized. After this recognition, the data on the brightness, corresponding to the image of the object, is extracted from the data on the brightness recorded in the storing means 30, and then the exposure value is calculated based on that. Thus, the appropriate exposure value is calculated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a photometric device for use in cameras such as electronic still cameras, silver halide cameras, and video cameras.

[Conventional technology]

In recent camera photometering devices, for example,
As described in Japanese Patent Application No. 9829, there has been provided a camera that is devised so that proper exposure can be obtained even in backlight situations where it is difficult to calculate the proper exposure. This detects the photographing magnification from the focal length of the photographic lens and the subject distance, and changes the calculation formula for the exposure value according to this photographic magnification. That is, a photometric area is defined according to the area occupied by the subject with respect to the photographic screen, and an arithmetic expression corresponding to this photometric area is selected. Then, the exposure value is calculated by substituting the brightness data obtained from the photometric area into the selected arithmetic expression.

[Problem to be solved by the invention]

However, in the photometry method described in the above publication, the pattern of the photometry area is predetermined, and there was a problem in that accurate exposure values could not be obtained unless the subject was placed in the center of the shooting screen. .

[Purpose of the invention]

The present invention was made in order to solve the above-mentioned problems, and an object of the present invention is to provide a photometry device that can calculate the appropriate exposure no matter where the subject is located within the shooting screen. do.

[Means to solve the problem]

In order to achieve the above object, the photometry device of the present invention performs photometry on a photographic screen divided into a matrix using a plurality of light receiving elements. The storage means records this photometered luminance data, and the binarization means binarizes it. The image recognition means scans this binarized image data both vertically and horizontally, detects the position and size of the subject, and compares it with pre-stored image patterns to determine the subject image. recognize. The brightness data corresponding to the recognized subject image is extracted from the brightness data not written in the storage means, and the arithmetic processing means calculates the exposure value based on the brightness data.

[Effect]

According to the above configuration, when the photometry device of the present invention captures a subject within the photographic screen, the brightness output in each area of the photographic screen measured by the light receiving element is recorded by the storage means, and the luminance output is recorded by the binarization means. Binarized. Next, the binarized image data is scanned in the vertical and horizontal directions to detect the position and size of the subject. The position and size of the subject are compared with pre-stored image patterns to perform image recognition of the subject. Once the subject image has been recognized, brightness data corresponding to this subject image is extracted from the brightness data recorded in the storage means, and an exposure value is calculated based on this.

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

〔Example〕

In FIG. 1 showing a block diagram of a photometric device of the present invention and an optical system of an electronic still camera 1 incorporating this photometric device, the optical system of the electronic still camera 1 includes a photographing lens 10. It consists of an instantaneous diaphragm 11° shutter 12, and behind this shutter 12, a CCD 15, which is a solid-state imaging device in which pixels are arranged two-dimensionally, is arranged. This CCD 15 includes a well-known sample/hold (S/H) preamplifier 16. Process amplifier 17. matrix 18,
An encoder 19 and a recording section 20 for writing video signals onto a still video floppy (hereinafter referred to as video floppy) are provided.

The s/H preamplifier 16 includes a low-pass filter (
LPF)23. Gate circuit 24. Integrating circuit 25, standardizing circuit 26. First memory circuit 27. Scanning and pattern recognition circuit 28. The photometry circuits 31 are connected to each other in order, and the scan & pattern recognition circuit 28 is connected to an RO.
M32 is connected. A huge amount of basic patterns that are referred to when performing pattern recognition are written in this ROM 32.

An A/D conversion circuit 29 is connected to the integration circuit 25, which converts analog photometric values for each pixel that are serially outputted into digital luminance data. A second storage circuit 30 is connected to this A/D conversion circuit 29.
The luminance data from the D conversion circuit 29 is stored in address order. This second storage circuit 30 is connected to a photometric circuit 31, which calculates the final exposure value P and controls the aperture 11 and shutter 12 based on this exposure value P. Note that the shutter 12 is always in an open state, and is temporarily closed only when receiving a control signal from the photometry circuit 31, and is opened and closed for an exposure time based on the exposure value P, and returns to the open state after the completion of shadowing. be done.

A CCD driver 21 is connected to the CCD 15, and this CCD driver 21 and the S/H preamplifier 1
6. Process amplifier 17. Matrix 18. A synchronization signal generation circuit 22 is connected to the encoder 19 and the gate circuit 24, which generates various pulses necessary for driving them, synchronizes these various pulses with each other, and generates a master clock pulse for controlling the sequence. ing.

Next, the operation of the photometric device of the present invention configured as above will be explained. First, when a video floppy is loaded into the electronic still camera 1 and the power is turned on, a master crotter pulse and various pulses are generated from the synchronization signal generation circuit 22, and the CCD driver 21. S/H preamplifier 16. Process amplifier 17. Matrix 18. The signal is sent to the encoder 19 and gate circuit 24, and their respective drives are started. The loaded video floppy starts rotating and reaches a steady rotation speed of 60 revolutions per second in about 30 m5.

When the photographic lens 10 is directed toward the subject, the optical image of the subject captured by the photographic lens 10 is captured by the CCD 15 as shown in FIG.
is imaged. When you press the release button halfway, the CCD
The optical image formed on 15 is converted into a luminance signal by CCD 15, sampled and amplified by S/H preamplifier 16, and input to LPF 23. Unnecessary high frequency components are removed from the H degree signal for each pixel by the LPF 23, and the gate circuit 24. After passing through the integrating circuit 25, A/
It is converted into a digital signal by the D conversion circuit and sent to the second storage circuit 3.
0 is written for each address.

On the other hand, the luminance signal output from the S/H preamplifier 16 is binarized by the standardization circuit 26, converted into a pattern as shown in FIG. 3, and written into the first storage circuit 27. In other words, since the brightness of the tree 40 and the person 41 shown in FIG. , identification data of "1" is input to the addresses corresponding to the background, etc. having luminance equal to or higher than the darkness value, respectively. In addition, identification data of "1" is input to the address corresponding to the extremely bright sun 42, so that it is no longer distinguishable from the background whose brightness is higher than the darkness value, and the standardized pattern shown in Figure 3 appears. Served.

The image data standardized in this way is taken into the scan color pattern recognition circuit 28 and horizontally and vertically scanned.
Waveforms as shown in FIGS. 4 and 5 are obtained, respectively. The portion where the identification data "0" is input has a waveform that protrudes downward in the horizontal scan shown in FIG. 4, and protrudes to the left in the vertical scan shown in FIG. By superimposing the waveform obtained by horizontal scanning and the waveform obtained by vertical scanning, the area of position 9 of the subject on the photographic screen is accurately detected.

By comparing the waveform pattern of this object with the basic pattern stored in the ROM 32 in advance, the tree 40 is excluded and it is recognized that the person 41 is the main object. The photometry circuit 31 detects the position of the person 41 from the scanning color pattern recognition circuit 28.

Referring to the area information, the brightness data stored at the address corresponding to this is extracted from the brightness data written in the second storage circuit 30, and the exposure value P is calculated based on this brightness data. .

When the release button is pressed in this state, the aperture 11 is narrowed down to a predetermined aperture based on the exposure value P, and at the same time the shutter 22 is opened and closed. The optical image, which has been controlled to have an appropriate amount of light, is converted into a video signal by the CCD 15, sampled and amplified by the S/H preamplifier 16, subjected to various corrections by the process amplifier 17, and input to the matrix 18. The video signal input to the matrix 18 is converted into a luminance signal and a color difference signal, which are combined into an NTSC color signal via an encoder 19 and input to the recording section 20. The video signal input to the recording section 20 is instantaneously recorded on a video floppy via a head amplifier and a magnetic head (not shown).

In addition, as shown in Figures 7 and 8, we focused on the fact that the width W of the subject changes depending on the area of the subject within the photographic screen, and as shown in Figure 6, from the edge of the head. If the distance is ξ, then ξ is a function with W as a parameter. As a result, the position and area of the subject's face can be detected from the width W of the subject, so the exposure value P may be calculated based on the brightness data of the face. In addition,
The upper part of the waveform due to horizontal scanning in Figs. 7 and 8 is “
The lower part shows the "backlit" time and the "spotlight" time when the main subject is brighter than the surroundings.

Although this embodiment has been described only for "backlight" photography, exposure values can be similarly obtained during "spotlight" photography. In other words, “spotlight”
At times, the waveforms generated by horizontal scanning and vertical scanning by the scan & pattern recognition circuit 28 are opposite to those in "backlight", but by comparing them with the subject pattern for "spotlight", they are exactly the same as in "backlight". Similarly, brightness data of the subject can be detected, and accurate exposure values can be calculated.

〔Effect of the invention〕

As explained above, according to the photometry device of the present invention, a plurality of light-receiving elements arranged in a matrix measure the light of the photographic screen, write each obtained brightness value in the storage means, and write each brightness value into the storage means. Standardize against. Perform horizontal scanning and vertical scanning on this standardized luminance data,
Pattern recognition of the object is performed using the obtained waveform. Then, the brightness data of the recognized object is extracted from the brightness data recorded in the storage means, and the exposure value is calculated based on this.

Therefore, it is possible to accurately detect the brightness data of the main subject, no matter where the subject is within the shooting screen, or even when shooting in situations where it is difficult to calculate the appropriate exposure, such as when shooting against the light or under a spotlight. Thus, it becomes possible to provide a photometry device that can reliably calculate an appropriate exposure value.

[Brief explanation of the drawing]

FIG. 1 is a block diagram schematically showing the structure of an embodiment of the present invention. FIG. 2 is a schematic diagram showing an example of a subject captured by an electronic still camera incorporating an embodiment of the present invention. FIG. 3 is a schematic diagram in which the luminance data of the subject shown in FIG. 2 is standardized. FIG. 4 shows a waveform obtained by horizontally scanning the luminance data shown in FIG. FIG. 5 shows a waveform obtained by vertically scanning the luminance data shown in FIG. FIG. 6 is a schematic diagram in which luminance data of one subject is standardized. FIG. 7 is a schematic diagram in which luminance data of one subject is standardized. FIG. 8 is a schematic diagram in which luminance data of one subject is standardized. 1...Electronic still camera 15...CCD 26...Standardization circuit 28...Scan & pattern recognition circuit 31...Photometering circuit 32...ROM. Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] (1) In a photometry device that divides a photographic screen into a matrix and includes a plurality of light-receiving elements that measure light for each of the divided areas, a storage means for recording luminance data measured for each of the areas; , a binarization means for binarizing the luminance data, and scanning the binarized image data in both vertical and horizontal directions to determine the position of the subject;
image recognition means for detecting the size and recognizing the subject image by comparing it with a pre-stored image pattern, and referring to the luminance data recorded in the storage means; 1. A photometric device comprising: arithmetic processing means for calculating an exposure value based on brightness data corresponding to a subject image.