JPH0830835B2 - Photometric device - Google Patents

Description

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 photometric devices for cameras, for example, Japanese Patent Laid-Open No. 61-27982
As described in Japanese Patent Laid-Open No. 9-93, there is provided a device that is devised so as to obtain an appropriate exposure even when the backlight is difficult to calculate. In this method, the shooting magnification is detected from the focal length of the shooting lens and the subject distance, and the calculation formula of the exposure value is changed according to the shooting magnification. That is, the photometric area is defined according to the size of the area occupied by the subject on the shooting screen, and the arithmetic expression corresponding to the 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.

[Problems to be Solved by the Invention]

However, in the photometric method described in the above publication, the pattern of the photometric area is predetermined, and there is a problem that an accurate exposure value cannot be obtained unless the subject is placed in the center of the shooting screen. .

[Object of the Invention]

The present invention has been made to solve the above problems, and an object of the present invention is to provide a photometric device that can calculate an appropriate exposure regardless of the position of a subject in a shooting screen. To do.

[Means for solving the problem]

In order to achieve the above object, the photometric device of the present invention divides the photographic screen into a matrix of photometric elements by a plurality of light receiving elements. The storage unit records the photometric brightness data and the binarization unit binarizes the data. The image recognition means performs vertical and horizontal bidirectional scanning on the binarized image data to detect the position and size of the subject and compare the subject image with a pre-stored image pattern. recognize. The brightness data corresponding to the recognized subject image is extracted from the brightness data written in the storage unit, and the arithmetic processing unit calculates the exposure value based on the brightness data.

[Action]

According to the above configuration, when the photometric device of the present invention captures an object in the shooting screen, the brightness output in each area of the shooting screen measured by the light receiving element is recorded by the storage means and the binarization means is used. It is binarized. Next, the binarized image data is scanned in the vertical and horizontal directions to detect the position and size of the subject. Image recognition of the subject is performed by comparing the position and size of the subject with an image pattern stored in advance. When the subject image is recognized, the brightness data corresponding to this subject image is extracted from the brightness data recorded in the storage means, and the exposure value is calculated based on this.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

〔Example〕

In the block diagram of the photometric device of the present invention and in FIG. 1 showing the optical system of an electronic still camera 1 incorporating this photometric device, the optical system of the electronic still camera 1 comprises a taking lens 10, an aperture stop 11 of an instantaneous aperture system, and a shutter 12. A CCD 15 which is a solid-state image pickup device in which pixels are two-dimensionally arranged is arranged behind the shutter 12. The CCD 15 has a well-known sample / hold (S / H) preamplifier 16, a process amplifier 17, a matrix 18, an encoder 19, and a recording unit 20 for writing a video signal to a still video floppy (hereinafter referred to as a video floppy). Is provided.

The S / H preamplifier 16 has a low-pass filter (LPF) 2
3, a gate circuit 24, an integrating circuit 25, a normalizing circuit 26, a first memory circuit 27, a scan & pattern recognition circuit 28, a photometric circuit 31 are connected in order, and further, the scan & pattern recognition circuit 28 is ROM32. Are connected. A huge amount of basic patterns that are referred to when performing pattern recognition are written in this ROM32.

The integrator circuit 25 converts the serially output analog photometric value of each pixel into digital luminance data.
The A / D conversion circuit 29 is connected. A second storage circuit 30 is connected to the A / D conversion circuit 29 and stores the brightness data from the A / D conversion circuit 29 in the order of addresses. The second memory circuit 30 is connected to the photometric circuit 31, and the photometric circuit 31
Calculates the final exposure value P and controls the diaphragm 11 and the shutter 12 based on this exposure value P. The shutter 12 is always open, and is closed only when the control signal from the photometric circuit 31 is received, and the exposure value P
It is opened and closed for the exposure time based on, and is returned to the open state after the end of shooting.

A CCD driver 21 is connected to the CCD 15,
CCD driver 21, the S / H preamplifier 16 and process amplifier 1
7, the matrix 18, the encoder 19 and the gate circuit 24,
A synchronization signal generation circuit 22 is connected which generates various pulses necessary for driving these, synchronizes these various pulses with each other, and generates a master clock pulse for controlling the sequence.

Next, the operation of the photometric device of the present invention configured as described above will be described. First, when a video floppy is loaded into the electronic still camera 1 and the power is turned on, a master clock pulse and various pulses are generated from the synchronization signal generation circuit 22, and the CCD driver 21, the S / H preamplifier 16, the process amplifier 17, respectively. Matrix 18, encoder 19, gate circuit 2
It is sent to 4 and each drive is started. The loaded video floppy starts rotating and reaches a steady speed of 60 rpm in about 30 ms.

When the taking lens 10 is aimed at the subject, an optical image of the subject captured by the taking lens 10 is formed on the CCD 15 as shown in FIG. When the release button is pressed halfway, the optical image formed on the CCD 15 is converted into a luminance signal by the CCD 15, sampled and amplified by the S / H preamplifier 16, and input to the LPF 23. The LPF 23 removes unnecessary high-frequency components from the luminance signal of each pixel, passes through the gate circuit 24 and the integrating circuit 25, and then is converted into a digital signal by the A / D conversion circuit, and then each address of the second memory circuit 30. It is written every time.

On the other hand, the luminance signal output from the S / H preamplifier 16 is binarized by the normalization circuit 26, converted into a pattern as shown in FIG. 3, and written in the first storage circuit 27. That is, since the brightness of the tree 40 and the person 41 shown in FIG. 2 respectively have brightness lower than a predetermined threshold value, “0” is assigned to each address of the first storage circuit 27 corresponding to the tree 40 and the person 41 The identification data of "1" is input to the address corresponding to the background or the like having the brightness equal to or higher than the threshold value. Further, the identification data of "1" is input to the address corresponding to the extremely high-intensity sun 42, and it is no longer distinguished from the background having the luminance equal to or higher than the threshold, and the standardized pattern shown in FIG. 3 appears. To be done.

The image data thus standardized is taken into the scan & pattern recognition circuit 28 and horizontally and vertically scanned,
The waveforms shown in FIGS. 4 and 5 are obtained, respectively. The portion of the identification data into which "0" is input has a waveform that projects downward in the horizontal scanning shown in FIG. 4 and projects leftward in the vertical scanning shown in FIG. By superimposing the waveform obtained by the horizontal scanning and the waveform obtained by the vertical scanning, the position and area of the subject on the photographing screen are accurately detected.

By comparing the waveform pattern of the subject with the basic pattern stored in the ROM 32 in advance, the tree 40 is excluded and the person 41 is recognized as the main subject.
The photometering circuit 31 scans the pattern recognition circuit 28 to the person 41.
Position information and area information, the brightness data stored at the address corresponding to the position information is extracted from the brightness data written in the second memory circuit 30, and the exposure value P is calculated based on this brightness data. To calculate.

When the release button is pressed in this state, the shutter 11 is opened and closed at the same time when the diaphragm 11 is narrowed down to a predetermined diaphragm based on the exposure value P. The optical image controlled to a proper light amount is converted into a video signal by the CCD15, sampled and amplified by the S / H preamplifier 16, and processed by the process amplifier.
Various corrections are made at 17 and the result is input to the matrix 18.
The video signal input to the matrix 18 is converted into a luminance signal and a color difference signal, combined into an NTSC color signal via the encoder 19, and input to the recording unit 20. The video signal input to the recording unit 20 is instantaneously recorded on the video floppy via a head amplifier and a magnetic head (not shown).

Further, as shown in FIGS. 7 and 8, paying attention to the fact that the width W of the subject changes depending on the size of the area of the subject within the photographing screen, as shown in FIG. If the distance of is ξ, this ξ is a function with W as a parameter. As a result, the position and area of the face of the subject can be detected from the width W of the subject, and the exposure value P may be calculated from the brightness data of the face. The upper part of the waveform of horizontal scanning in FIGS. 7 and 8 indicates "backlight", and the lower part thereof indicates "spotlight" where the main subject has higher brightness than the surroundings.

It should be noted that although the present embodiment has been described only for "backlit" shooting, the exposure value can be similarly obtained also for "spotlight" shooting. That is, in the "spotlight", the waveforms of the horizontal scanning and the vertical scanning by the scan & pattern recognition circuit 28 are opposite to those in the "backlighting", but they should be matched with the subject pattern for the "spotlighting". Thus, the brightness data of the subject can be detected exactly as in the case of "backlight", and the accurate exposure value can be calculated.

〔The invention's effect〕

As described above, according to the photometric device of the present invention,
A plurality of light receiving elements arranged in a matrix are used to measure the photographic screen, and the obtained brightness values are written in the storage means, and the brightness values are standardized. Horizontal scanning and vertical scanning are performed on the standardized luminance data, and pattern recognition of the subject is performed based on the obtained waveform. Then, the recognized brightness data of the subject is extracted from the brightness data recorded in the storage means, and the exposure value is calculated based on the extracted brightness data.

Therefore, no matter where the subject is in the shooting screen,
In addition, the brightness data of the main subject can be accurately detected, and the proper exposure value can be reliably calculated, even during shooting such as "backlight" or "spotlight" where it is difficult to calculate the proper exposure. A photometric device can be provided.

[Brief description of drawings]

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 the luminance data of one subject is standardized. FIG. 7 is a schematic diagram in which the luminance data of one subject is standardized. FIG. 8 is a schematic diagram in which the luminance data of one subject is standardized. 1 …… Electronic still camera 15 …… CCD 26 …… Standardization circuit 28 …… Scan & pattern recognition circuit 31 …… Photometry circuit 32 …… ROM.

Claims (1)

[Claims] 1. A photometric device comprising a plurality of light receiving elements for dividing a photographic screen into a matrix and photometrically measuring each of the divided regions, and a memory for recording luminance data measured for each of the regions. Means, a binarizing means for binarizing the luminance data, and a vertical and horizontal bidirectional scanning of the binarized image data to position the object,
An image recognition unit for recognizing a subject image by detecting a size and comparing it with a pre-stored image pattern, and the brightness data recorded in the storage unit are referred to and recognized by the image recognition unit. And a calculation processing unit that calculates an exposure value based on the brightness data corresponding to the subject image.